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Home -> Community -> Usenet -> c.d.o.server -> xujian111
What is claimed is:
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to the coupling of
selected input and output lines or channels through which optical
signals are directed, and to the routing of optical signals to and from
such lines or channels. More specifically, the present invention
relates to an optical-based analysis system and method that utilizes a
device adapted to effect selection and coupling through coordinated
mechanical indexing movements and/or the use of optical fiber bundles
whose ends are exposed to a detector. Such a device provides advantage
in a wide variety of fields of application, particularly in
applications involving the generation and transmission of analytical
information. Specific fields of use include the preparation, sampling
and analyzing of soluble materials as well as the testing of other
fluids and solid materials exhibiting optical characteristics.
BACKGROUND OF THE INVENTION
[0002] Optical transport techniques are often utilized to direct a beam
or pulse of light from a light source to a test site and, subsequently,
to carry analytical information generated or measured at the test site
to a suitable light receiving device. Analytical information
transmitted by optical means can be chemical or biological in nature.
For example, the analytical information can be used to identify a
particular analyte, i.e., a component of interest, that is resident
within the sample contained at the test site and to determine the
concentration of the analyte. Examples of analytical signals include,
among others, emission, absorption, scattering, refraction, and
diffraction of electromagnetic radiation over differing ranges of
spectra. Many of these analytical signals are measured through
spectroscopic techniques. Spectroscopy generally involves irradiating a
sample with some form of electromagnetic radiation (i.e., light),
measuring an ensuing consequence of the irradiation (e.g., absorption,
emission, or scattering), and interpreting of the measured parameters
to provide the desired information. An example of an instrumental
method of spectroscopy entails the operation of a spectrophotometer, in
which a light source in combination with the irradiated sample serves
as the analytical signal generator and the analytical signal is
generated in the form of an attenuated light beam. The attenuated
signal is received by a suitable input transducer such as a photocell.
The transduced signal, such as electrical current, is then sent to a
readout device.
[0003] As one example for implementing spectral analysis, a
spectrophotometer uses ultraviolet (UV) and/or visible light, or in
other cases infrared (IR) or near infrared (NIR) light, to scan the
sample and calculate absorbance values. In one specific method
involving the UV or UV-visible spectrophotometer, the UV sipper method,
the sample is transferred to a sample cell contained within the
spectrophotometer, is scanned while residing in the sample cell, and
preferably is then returned to the test vessel.
[0004] The concentration of a given analyte in a sample through
spectrochemical determination typically involves several steps. These
steps can include (1) acquiring an initial sample; (2) performing
sample preparation and/or treatment to produce the analytical sample;
(3) using a sample introduction system to present the analytical sample
to the sample holding portion of a selected analytical instrument
(e.g., transferring the sample to the sample-holding portion of a UV
spectrophotometer); (4) measuring an analytical signal (e.g., an
optical signal) derived from the analytical sample; (5) establishing a
calibration function through the use of standards and calculations; (6)
interpreting the analytical signal based on sample and reference
measurements; and (7) feeding the interpreted signal to a readout
and/or recording system.
[0005] Conventional equipment employed in carrying out the above
processes are generally known in various forms. Measurement of the
analytical signal involves employing a suitable spectrochemical
encoding system to encode the chemical information associated with the
sample, such as concentration, in the form of an optical signal. In
spectrochemical systems, the encoding process entails passing a beam of
light through the sample under controlled conditions, in which case the
desired chemical information is encoded as the magnitude of optical
signals at particular wavelengths. Measurement and encoding can occur
in or at sample cells, cuvettes, tanks, pipes, solid sample holders, or
flow cells of various designs.
[0006] In addition, a suitable optical information selector is
typically used to sort out or discriminate the desired optical signal
from the several potentially interfering signals produced by the
encoding process. For instance, a wavelength selector can be used to
discriminate on the basis of wavelength, or optical frequency. A
radiation transducer or photodetector is then activated to convert the
optical signal into a corresponding electrical signal suitable for
processing by the electronic circuitry normally integrated into the
analytical equipment. A readout device provides human-readable
numerical data, the values of which are proportional to the processed
electrical signals.
[0007] For spectrophotometers operating according to UV-visible
molecular absorption methods, the quantity measured from a sample is
the magnitude of the radiant power or flux supplied from a radiation
source that is absorbed by the analyte species of the sample. Ideally,
a value for the absorbance A can be validly calculated from Beer's law:
1 A = - log T = - log 0 = abc ,
[0008] where T is the transmittance, P.sub.0 is the magnitude of the
radiant power incident on the sample, P is the magnitude of the
diminished (or attenuated) radiant power transmitted from the sample, a
is the absorptivity, b is the pathlength of absorption, and c is the
concentration of the absorbing species.
[0009] It thus can be seen that under suitable conditions, absorbance
is directly proportional to analyte concentration through Beer's law.
The concentration of the analyte can be determined from the absorbance
value, which in turn is calculated from the ratio of measured radiation
transmitted and measured radiation incident. In addition, a true
absorbance value can be obtained by measuring a reference or blank
media sample and taking the ratio of the radiant power transmitted
through the analyte sample to that transmitted through the blank
sample.
[0010] In some types of conventional sample testing systems, samples
are transferred sequentially to one or more sample cells that are
contained within the analytical instrument (e.g., spectrophotometer)
itself. Samples are first taken from test vessels and, using sampling
pumps, carried over sampling lines and through sampling filters. The
samples are then transported to a UV analyzer, an HPLC system, a
fraction collector, or the like. The analytical instrument may include
a carousel that holds several sample cuvettes, such that rotation of
the carousel brings each cuvette into position at the sample cell in a
step-wise manner. The pulsing of the light source supplying the initial
optical signal can be synchronized by control means with the rotation
of the carousel.
[0011] Examples of UV-vis spectrophotometers are those available from
Varian, Inc., Palo Alto, Calif., and designated as the CARY.TM. Series
systems. In particular, the Varian CARY 50.TM. spectrophotometer
includes a sample compartment that contains a sample cell through which
a light beam or pulse passes. Several sizes of sample cells are
available. In addition, the spectrophotometer can be equipped with a
multi-cell holder that accommodates up to eighteen cells. A built-in
movement mechanism moves the cells past the light beam.
[0012] Many conventional sample testing systems require either a
plurality of active measurement beams, a plurality of active detectors,
or both. For instance, U.S. Pat. No. 4,431,307 discloses a cuvette-set
matrix containing an array of cuvettes adapted for use in measuring
liquid samples using light beams. The cuvette-set matrix is adapted to
receive a matrix of measurement beams such that one measurement beam is
associated with each cuvette. A matrix of detectors is disposed on the
side of the cuvettes opposite to the side at which the matrix of
measurement beams is disposed. Thus, for each cuvette, the measurement
beam emitted from the source passes through the liquid contained in the
cuvette, and into the individual detector associated with that cuvette.
[0013] In other recently developed systems, fiber-optics are being used
in conjunction with UV scans to conduct in-situ absorption
measurements--that is, measurements taken directly in the sample
containers of either dissolution test equipment or sample analysis
equipment. Fiber optic cables consist of, for example, glass fibers
coaxially surrounded by protective sheathing or cladding, and are
capable of carrying monochromatic light signals.
[0014] One recent example of an in-situ fiber-optic method associated
with dissolution testing is disclosed in U.S. Pat. No. 6,174,497. This
method involves submerging a dip-type fiber-optic UV probe in test
media contained in a vessel. Several probes can be operatively
associated with a corresponding number of test vessels, with each probe
communicating with its own UV spectrometer. A light beam (UV radiation)
provided by a deuterium lamp is directed through fiber-optic cabling to
the probe. Within the probe, the light travels through a quartz lens
seated directly above a flow cell-type structure, the interior of which
is filled with a quantity of the test media. The light passes through
the test media in the flow cell, is reflected off a mirror positioned
at the terminal end of the probe, passes back through the flow cell and
the quartz lens, and travels through a second fiber-optic cable to a
spectrometer.
[0015] Another recent example of an in-situ fiber-optic method
associated with dissolution testing utilizes a U-shaped dip probe that
is inserted into a test vessel. One leg of the U-shaped probe contains
a source optical fiber and the other leg contains the return optical
fiber. A gap between the ends of the fibers is defined at the base of
the U-shape, across which the light beam is transmitted through the
media of the test vessel.
[0016] For the previously described Varian CARY 50.TM.
spectrophotometer, a fiber-optic dip probe coupler is available to
enable in-situ sample measurement methods and effectively replace the
need for a sipper accessory. This fiber optic coupler can be housed in
the spectrophotometer unit in the place of the conventional sample
cell. The coupler includes suitable connectors for coupling with the
source and return optical fiber lines of a remote fiber-optic dip
probe. The light beam from the light source of the spectrophotometer is
directed to source line of the dip probe, and the resulting optical
signal transmitted back to the spectrophotmeter through the return
line.
[0017] Fiber optics have also been employed in connection with
sample-holding cells. For example, U.S. Pat. No. 5,715,173 discloses an
optical system for measuring transmitted light in which both a sample
flow cell and a reference flow cell are used. Light supplied from a
light source is transmitted through an optical fiber to the sample flow
cell, and also through a second optical fiber to the reference flow
cell. The path of transmitted light from each flow cell is directed
through respective optical fibers toward an optical detector, and is
controlled by an optical path switcher in the form of a light selecting
shutter or disk.
[0018] It is acknowledged by persons skilled in the art that, when
working with an array of flow cells, sample cells, cuvettes, probes,
and other instruments of optical measurement, and particularly in
connection with fiber-optic components, there remains a need for
efficiently and effectively routing or distributing light energy to and
from such sample containers. This need has been the subject of some
developmental efforts.
[0019] For instance, U.S. Pat. No. 5,526,451 discloses a fiber-optic
sample analyzing system in which a plurality of cuvettes each have a
source optical fiber and a return optical fiber. A device is provided
for selecting a source fiber to receive radiation for passage through a
selected sample of one of the cuvettes, and for returning transmitted
radiation from the selected cuvette through a selected return fiber to
a spectrophotometer. The selection device includes a single rotatable
retaining member supporting the respective ends of eight fiber-optic
input lines and eight corresponding fiber-optic output lines. The
respective ends of the fiber-optic lines are arranged in a ring around
the central axis of the retaining member. The eight input lines define
one half of the ring while the eight output lines define the other
half. By this arrangement, each input line end affixed to the retaining
member has a corresponding output line end affixed in diametrically
opposite relation along the ring. Rotation of the retaining member
determines which pair of input and output lines are respectively
aligned with an input lens and an output lens disposed in spaced
relation to the retaining member. A source beam passes through the
input lens and into the selected input line at the end supported by the
retaining member. The source beam then travels through the input line
and into the sample cuvette associated with that particular input line.
>From the sample cuvette, the transmitted beam travels through the
output line associated with the selected input line and sample cuvette.
This output line terminates at its end supported by the retaining
member. Since this output end is aligned with the output lens spaced
from the retaining member, the transmitted beam passes through the
output lens and is conducted to the analyzing means of the
spectrophometer.
[0020] U.S. Pat. No. 5,112,134 discloses a vertical-beam photometric
measurement system for performing enzyme-linked immunoabsorbent assay
(ELISA) techniques. The system includes a light coupling and
transmission mechanism utilizing a cylindrical rotor and a fiber-optic
distributor. The mechanism receives light from a light assembly. The
cylindrical rotor includes an optical fiber having an input end located
at its center, and an output end located near its periphery. As the
rotor rotates, the input end of the fiber of the rotor remains
stationary with respect to the light assembly, while the output end
moves around a circular path. The light output of the fiber of the
rotor is received by a fiber optic distributor containing a
multiplicity of optical fibers having their respective input ends
arranged in a circular array. As the rotor is indexed about its axis,
the output end of its fiber can be brought into alignment with
successive fibers of the distributor. On the output side of the
distributor, the multiplicity of fibers lead to a fiber manifold. The
manifold aligns each fibers with a corresponding one of a multiplicity
of assay sites. The assay sites are contained in a standard microplate
consisting of an 8.times.12 array of optically transparent sample
wells. Lens arrays are provided above and below the microplate to focus
the beam of light passing through each individual sample well of the
microplate. A detector board is located immediately below the lower
lens array. The detector board contains an array of photodetectors
corresponding to the array of sample wells. Thus, light from a selected
fiber passes through a lens of the first lens array, the contents of
the corresponding sample well, a corresponding lens of the second lens
array, and into the corresponding photodetector of the detector board.
In the conventional manner, the photodetector senses the intensity of
the incident light that passed through the corresponding sample well
and produces an electrical output signal proportional to the intensity.
As in other vertical-beam systems adapted to scan samples contained in
horizontally-oriented multi-well plates, this system requires a
plurality of photedetectors and is not capable of routing the incident
light from each sample well to a single detection means.
[0021] U.S. Pat. No. 6,151,111 also discloses a vertical-beam
photometric system in which a plate carrier sequentially advances an
8.times.12 microplate through a measurement station. Each column of
eight wells is scanned by light emitted from a bundle of eight
corresponding distribution optical fibers. Light supplied from a light
source passes through a monochromator to a rotor assembly. Each of the
eight distribution fibers enables light from the rotor assembly to be
sequentially directed by a corresponding mirror vertically through a
corresponding aperture, lens, and microplate well, and subsequently
into a corresponding photodetector lens. The rotor assembly consists of
two mirrors positioned so as to bend light received by the rotor
assembly 180 degrees, after which the light can be directed into one of
the distribution fibers. The rotor can then be moved into alignment
with another distribution fiber.
[0022] U.S. Pat. No. 4,989,932 discloses a multiplexer for enabling the
sampling of a number of different samples. The multiplexer contains a
stationary cylindrical outer body and a rotatable optical barrel
disposed within the outer body. A primary inlet port is located on one
side of the outer body through which light is introduced into the
multiplexer. A primary exit port is located on an opposing side of the
outer body through which light exits the multiplexer for transmission
to an apparatus for optically analyzing a sample. Pairs of ancillary
inlet and exit ports are disposed around the cylindrical wall of the
outer body, and are oriented radially (or transversely) with respect to
the longitudinal axis. The rotatable barrel contains a first mirror and
lens associated with the ancillary exit ports, and a second mirror and
lens associated with the ancillary inlet ports. A stepper motor is used
to rotate the barrel to successively align the mirrors and lenses with
a selected pair of ancillary inlet and exit ports. Light transmitted
through the primary inlet port along the longitudinal axis of the
multiplexer is turned at a right angle by the first mirror, passes
through the first lens, and exits the multiplexer through the selected
ancillary exit port. From the selected ancillary exit port, the light
is transmitted through a fiber-optic bundle to a sample and returns to
the multiplexer through the corresponding selected ancillary inlet
port. From the selected ancillary inlet port, the light passes through
the second lens, is turned at a right angle by the second mirror, and
exits the multiplexer along the longitudinal axis. Other pairs of
ancillary inlet and exit ports can be selected by rotating the barrel.
In another embodiment disclosed in this patent, incoming light is
received by an optical rod that has an angled mirrored surface at its
end. Rotation of the rod by a stepper motor positions the angled
mirrored surface to direct the light into a selected fiber-optic
bundle.
[0023] U.S. Pat. No. 4,528,159 discloses a sample analysis system in
which a belt containing a series of disposable reaction cuvettes is
driven along a track so as to guide the cuvettes through several
analysis stations. A separate photodetector tube is required for each
analysis station. Light guides are used to transmit light from a light
source, through filter wheels, through the reaction compartments of the
cuvettes, and to the photodetectors.
[0024] U.S. Pat. No. 5,804,453 discloses a system in which a
fiber-optic biosensor probe is inserted into a test tube. The probe
receives a light beam from a light source and sends a testing signal to
the photodetectors of a spectrometer. Time division multiplexing and
demultiplexing is implemented to distribute light to and from several
biosensors. Switching among inputs and outputs is controlled by an
input control signal provided by an electronic clocked counter.
[0025] U.S. Pat. No. 5,580,784 discloses a system in which a plurality
of chemical sensors are associated with several sample vials and
arranged between a light source and a photodetector. Optical fibers are
used to direct radiation into each sensor, as well as to direct
emissions out from the sensors. A wavelength-tunable filter is combined
with an optical multiplexer to direct radiation serially to each sensor
through the fibers.
[0026] In view of the current state of the art, there is a continuing
need for improved means for efficiently and effectively routing or
distributing light energy to and from sample testing sites. It would be
therefore be advantageous to provide a fiber-optic channel selection
apparatus and method that utilize mechanical components to effect
indexing among several optical input and/or output channels in an
efficient and controlled manner without the need for costly
optics-based switching components. In particular, it would be
advantagous to provide an apparatus and method that enable analysis of
multiple samples using only a single light source and a single
detection means. Such an apparatus should be designed to minimize light
loss and be compatible with a wide range of optical-based measurement
systems. The present invention is provided to address these and other
problems associated with the prior art.
SUMMARY OF THE INVENTION
[0027] According to one embodiment of the present invention, a sample
measurement and analysis system comprises an optical channel selecting
apparatus, a plurality of optical source lines, a plurality of optical
return lines, a plurality of sample test sites, and an optical
receiving device.
[0028] The optical channel selecting apparatus of the sample
measurement and analysis system comprises an optical input selection
device, an optical output selection device, and a controller element.
The optical input selection device defines a first optical path running
between a first input end and a first output end. The first output end
is rotatable to a plurality of first index positions defined along a
first circular path. The optical output selection device defines a
second optical path running between a second input end and a second
output end. The second input end is rotatable to a plurality of second
index positions defined along a second circular path. The controller
element communicates with the optical input selection device and the
optical output selection device for selectively aligning the first
optical path with the first index positions and the second optical path
with the second index positions.
[0029] Preferably, the controller element comprises a rotatable
coupling mechanism interconnecting the optical input selection device
and the optical output selection device. Rotation of the coupling
mechanism causes synchronized rotation of the first output end of the
first optical path and the second input end of the second optical path.
[0030] In accordance with this embodiment, a light source can be
optically coupled with the first input end of the first optical path.
The plurality of optical source lines correspond to the plurality of
first index positions and selectively communicate with the first
optical path. The plurality of optical return lines correspond to the
plurality of second index positions and selectively communicate with
the second optical path. Each sample test site optically communicates
with a corresponding one of the optical source lines and a
corresponding one of the optical return lines. The optical signal
receiving device optically communicates with the second output end of
the second output path.
[0031] According to the invention, the sample test sites can take on
various forms, depending on the particular function of purpose of the
system in which the fiber-optic channel selecting apparatus is
implemented. Non-limiting examples include sample containers, sample
holders, sample cells, flow cells, optically transmissible multi-well
plates, tanks, pipes, test vessels, cuvettes, test tubes, vials, and
fiber-optic probes or dip probes. In one specific application of the
invention, dip probes are insertable into test vessels containing the
bulk media from which samples are taken or extracted. Insertion of the
probes can be effected either manually or through automated means. The
vessels can, for instance, contain dissolution media and be mounted on
or otherwise supported by a dissolution test apparatus adapted to
prepare the dissolution media. In other implementations, sample cells
or flow cells are provided remotely in relation to the test vessels,
and a suitable sample media transport system is provided for
transferring samples to and from the cells and the vessels.
[0032] According to the invention, the optical signal receiving device
can constitute any number of types of instruments, depending on the
particular function of purpose of the system in which the fiber-optic
channel selecting apparatus is implemented. In a specific exemplary
embodiment of the invention, the optical signal receiving device is an
optical detector such as a photodetector, phototube, photocell, or
diode array.
[0033] According to another embodiment of the present invention, the
fiber-optic channel selecting apparatus of the sample measurement and
analysis system comprises an optical input selection device, an optical
output selection device, and a rotatable coupling mechanism
interconnecting the optical input selection device and the optical
output selection device. The optical input selection device is
rotatable about a first central axis, and comprises a first internal
optical fiber having a first input end and a first output end. The
first input end is disposed collinearly with the first central axis,
and the first output end disposed at a radially offset distance from
the first central axis. The optical output selection device is
rotatable about a second central axis, and comprises a second internal
optical fiber having a second input end and a second output end. The
second input end is disposed at a radially offset distance from the
second central axis, and the second output end disposed collinearly
with the second central axis. Rotation of the coupling mechanism causes
rotation of the first output end and the second input end.
[0034] In accordance with this embodiment, a light source can be
optically coupled with the first input end of the first internal
optical fiber. The plurality of optical source lines have respective
source line input ends. Each source line input end is selectively
optically alignable with the first output end of the first internal
optical fiber. The plurality of optical return lines have respective
return line output ends. Each return line output end is selectively
optically alignable with the second input end of the second internal
optical fiber. Each sample test site optically communicates with a
corresponding one of the optical source lines and a corresponding one
of the optical return lines. The optical signal receiving device
optically communicates with the second output end.
[0035] According to an additional embodiment of the present invention,
the sample measurement and analysis system comprises a fiber-optic
channel selecting apparatus, a plurality of optical source lines, a
mounting member, a plurality of optical return lines, a plurality of
sample test sites, and an optical signal receiving device.
[0036] In this embodiment, the fiber-optic channel selecting apparatus
comprising a rotary element rotatable about a central axis, and an
internal optical fiber having an internal optical fiber input end and
an internal optical fiber output end. The internal optical fiber input
end is disposed collinearly with the central axis, and the internal
optical fiber output end disposed at a radially offset distance from
the central axis. A light source can be optically coupled with the
first input end. The optical source lines have respective source line
input ends. Each source line input end is selectively optically
alignable with the internal optical fiber output end. The optical
return lines have respective return line output ends. Each return line
output end is fixedly supported by the mounting member. Each sample
test site optically communicates with a corresponding one of the
optical source lines and a corresponding one of the optical return
lines. The optical signal receiving device is optically aligned with
each return line output end.
[0037] According to a further embodiment of the present invention, a
sample measurement and analysis system comprises an optical channel
selection device, a plurality of optical source lines, a plurality of
optical probes, and a plurality of optical return lines. The optical
channel selection device defines an optical path running between an
input end and an output end. The optical path is adjustable to a
plurality of input channel positions. Each optical source line
corresponds to a respective input channel position, and is selectively
coupled to the optical path. Each probe is coupled to a respective
source line. Each optical return line is coupled to a respective probe.
[0038] As described herein, the optical channel selecting apparatus of
the inventive system can be provided as a mechanical, rotary
fiber-optic multiplexer (and demultiplexer) apparatus for selecting
channels through which a beam or pulse of light is routed in an
indexing manner. The apparatus comprises one, two, or more rotary
indexing devices. One of the rotary indexing devices demultiplexes a
beam of light by distributing the light from a single, common outgoing
or source line into a selected one of a plurality of outgoing or source
channels. The selection is accomplished by rotating the demultiplexing
device into a position at which the common outgoing or source line can
optically communicate with the selected outgoing channel. The other
rotary indexing device, when employed in the optical channel-selecting
apparatus, multiplexes a beam of light for transmission into a single
incoming or return line by selecting a selected one of a plurality of
incoming or return channels. The selection is accomplished by rotating
the multiplexing device into a position at which the common incoming or
return line can optically communicate with the selected incoming or
return channel. As an alternative to employing the multiplexing device,
each incoming or return line can be optically aligned with a signal
receiving means such as a photodetector, thereby eliminating the need
for the second rotary indexing device and the common incoming or return
line.
[0039] When two such rotary devices are provided in this manner, they
can be mechanically interfaced so that rotation of one device concurs
with rotation of the other device, with the result that the selection
of a certain channel of the one device concurs with the selection of a
corresponding channel of the other device. For instance, if each device
includes twelve channels and thus twelve index positions, the selection
of the channel at index position 1 of the one device simultaneously
results in the selection of the channel at index position 1 of the
other device.
[0040] According to an embodiment of the invention, each rotary device
comprises two fixed components (i.e., first and second fixed
components), a rotary component, and one or more bearings providing an
interface between the fixed components and the rotary component. The
rotary component is interposed between the two fixed components. Each
fixed component faces a respective end of the rotary component. One of
the fixed components (e.g., the first fixed component) has an optical
aperture at its axial center. The other fixed component (e.g., the
second fixed component) has a plurality of optical apertures oriented
in a circular arrangement about its axial center. The number of optical
apertures in the circular arrangement corresponds to the number of
optical channels selectable by the apparatus of the invention. The
rotary component has a light guiding path such as an optical fiber
having one end located at the axial center of the rotary component and
another end located radially outward with respect to the axial center.
The centrally located end of the optical fiber of the rotary component
is separated from the centrally located optical aperture of the first
fixed component by a very small air gap. The offset end of the optical
fiber of the rotary component is likewise separated from the plurality
of optical apertures of the second fixed component by a very small air
gap. These air gaps optimize light transmission while minimizing light
loss, and avoid the necessity of using expensive additional optical
components to couple the respective apertures and fiber ends of the
fixed and rotary components. Indexed rotation of the rotary component
with respect to the second fixed component results in selective
coupling between the offset end of the optical fiber of the rotary
component and each aperture of the second fixed component.
[0041] As indicated previously, the two rotary devices included with
the optical channel selecting apparatus can be made to rotate together
through a mechanical interface. This interface can be accomplished
through a suitable set of gears arranged such that rotation of at least
one gear results in rotation of both rotary devices. For example, each
rotary device could be provided with its own gear, and each of these
gears could be placed in meshing engagement with a third gear. While
manual rotation of the third gear in order to rotate the other gears is
possible, it is preferred that the third gear be powered through
connection to a motor or similarly automated device. The motor could
then be electronically controlled by suitable electronic hardware
and/or software. As an alternative to providing gears with each rotary
device, gear-like teeth could be formed on respective structures of the
rotary devices to eliminate additional gearing. In either case, the
rotary devices of the apparatus can be rotated continuously without the
need to reverse rotation upon completion of the indexing of each
channel provided. For instance, for a twelve-channel apparatus, the
sampling interval from index position 1 to index position 2 is
equivalent to the sampling interval from index position 12 to index
position 1.
[0042] As an alternative, the first rotary device utilized to select an
outgoing channel is provided, but the second rotary device utilized to
select an incoming channel is eliminated in favor of suitably
collecting a bundle of optical return fibers constituting the incoming
channels at a fixed position at which the ends of the fibers are
optically aligned with the receiving window of a optical detection
device.
[0043] The invention as just described offers advantages when
incorporated into any system that includes one or more light sources
and one or more devices adapted for receiving light energy from the
light sources. In such systems, the mechanical
multiplexing/demultiplexing functions realized by the present invention
are useful in networking one or more light signals from selected light
sources to selected receiver devices. The invention also offers
advantages when incorporated into any system that uses optics to route
optical signals over several lines or channels between a single light
source and a single detector. An example of this latter system is a
UV-vis spectrophotometer, which is generally designed to conduct UV
scans on prepared samples. It is often desirable to scan a multitude of
samples. In accordance with the present invention, each sample can be
held in a test vessel or a suitable cell or well, or in any other
suitable sample holding or containment means, and fiber-optic input and
output lines can be brought into operative communication with each
sample test site, or with each probe associated with the sample test
site. In this manner, each cell, probe, vessel or test site
respectively becomes associated with one of the channels of the
apparatus of the invention, and hence becomes associated with the
corresponding index positions of the rotary device or devices of the
apparatus. Accordingly, the selection of index position 1 of each
rotary device, for example, corresponds to the selection of test vessel
1, cell 1, and so on.
[0044] The fiber-optic channel selecting apparatus according to any of
embodiments described herein can be directly integrated into the design
of an optical-based sample measurement and/or analysis system or
instrument, such as a spectroscopic apparatus. An example of a
spectroscopic apparatus is a spectrophotometer.
[0045] According to another aspect of the present invention, a method
for acquiring data from samples comprises the following steps. A
plurality of samples are respectively disposed at a plurality of test
sites. A plurality of optical source lines are provided such that each
source line communicates with a corresponding one of the plurality of
test sites. A plurality of optical return lines are provided such that
each return line communicates with a corresponding one of the test
sites. A test site and its corresponding source line and return line
are selected by rotating a fiber-optic channel selecting apparatus to a
position at which a light source is coupled to the selected source
line. An optical signal of a first intensity is sent through the
selected source line to the selected test site to expose the sample
that is disposed at the selected test site. An optical signal of a
second intensity is emitted from the selected test site and travels
through the selected return line. This process can be repeated for
additional samples of the plurality of samples provided.
BRIEF DESCRIPTION OF THE DRAWINGS
[0046] FIG. 1 is a perspective view of a fiber-optic channel selection
apparatus provided in accordance with the present invention;
[0047] FIG. 2 is a side elevation view of the apparatus illustrated in
FIG. 1;
[0048] FIG. 3 is a top plan view of the apparatus illustrated in FIG.
1;
[0049] FIG. 4 is a rear elevation view of the apparatus illustrated in
FIG. 1 showing the interconnection of rotary devices provided in
accordance with one embodiment of the present invention;
[0050] FIG. 5A is a cross-sectional view of a rotary device for
distributing a light beam or signal from a single input to one or more
fiber-optic channels in accordance with the present invention;
[0051] FIG. 5B is a cross-sectional view of a rotary device for
distributing light beams or signals from one or more fiber-optic
channels to a single output in accordance with the present invention;
[0052] FIG. 6A is a cross-sectional view of an optical input selection
device provided with the apparatus illustrated in FIGS. 1-4, including
the rotary device illustrated in FIG. 5A;
[0053] FIG. 6B is cross-sectional view of an optical output selection
device provided with the apparatus illustrated in FIGS. 1-4, including
the rotary device illustrated in FIG. 5B;
[0054] FIG. 7A is a plan view illustrating either the input side of the
optical input selection device illustrated in FIG. 6A or the output
side of the optical output selection device illustrated in FIG. 6B;
[0055] FIG. 7B is a plan view illustrating either the output side of
the optical input selection device illustrated in FIG. 6A or the input
side of the optical output selection device illustrated in FIG. 6B;
[0056] FIG. 7C is a perspective view of either of the optical input
selection device illustrated in FIG. 6A or the optical output selection
device illustrated in FIG. 6B;
[0057] FIG. 8 is a schematic diagram of an analytical testing and data
acquisition system in which the apparatus or portions thereof
illustrated in FIGS. 1-7C is incorporated in accordance with the
present invention;
[0058] FIG. 9 is a schematic diagram of a fiber-optic probe operating
in conjunction with a test vessel and a spectrophotometer according to
conventional methods;
[0059] FIG. 10 is a schematic diagram of an in-situ measurement system
incorporating the use of the apparatus or portions thereof illustrated
in FIGS. 1-7C in combination with fiber-optic probes or similar
instruments;
[0060] FIG. 11 is a schematic diagram of an analytical testing and data
acquisition system provided in accordance with another embodiment of
the present invention;
[0061] FIG. 12A is a front elevation view of a fiber-optic bundle
mounting component provided with the apparatus illustrated in FIG. 11;
and
[0062] FIG. 12B is a cross-sectional side view of the mounting
component illustrated in FIG. 12A.
DETAILED DESCRIPTION OF THE INVENTION
[0063] In general, the term "communicate" (e.g., a first component
"communicates with" or "is in communication with" a second component)
is used herein to indicate a structural, functional, mechanical,
optical, or fluidic relationship between two or more components or
elements. As such, the fact that one component is said to communicate
with a second component is not intended to exclude the possibility that
additional components may be present between, and/or operatively
associated or engaged with, the first and second components.
[0064] As used herein, the term "multiplexer" is broadly defined to
indicate a system or device that includes a plurality of independent,
individual input lines or channels and a single output line or channel
(i.e., a common path or bus). One of the input lines can be selected so
that its value or signal is transmitted or routed over the output line.
Thus, the multiplexer could also be referred to as a data selector. In
addition, the term "demultiplexer" is broadly defined herein as
implementing the converse function of the multiplexer. That is, a
demultiplexer is a system or device that includes one input line or
channel (i.e., a common path or bus) and a plurality of output lines or
channels. One of the output lines is selected to receive the value or
signal provided by the input line. Thus, the demultiplexer could also
be referred to as a data distributor. These terms, as used herein, are
therefore intended to have a broader meaning than, for instance, the
meanings typically understood by persons associated with the
communications or electronics industries, wherein the terms are often
restricted to meaning a system in which all elements of a given signal
are observed simultaneously. For convenience, the term "multiplexer" or
"multiplexing apparatus" as used hereinafter is intended to cover a
device or system that includes a multiplexer and/or a demultiplexer.
[0065] As used herein, the terms "beam," "pulse," and "optical signal"
are intended to be interchangeable to indicate that the present
invention is applicable to the transmission of light energy by both
continuous and non-continuous methods.
[0066] As used herein, the terms "aperture" and "bore" are used
interchangeably to denote any opening through which light energy can be
transmitted with an acceptable degree of efficiency and an acceptable
minimum of light loss. Such an opening can include an optical fiber for
these purposes as well. Whether the term "aperture" or "bore" is more
appropriate could, for instance, depend on the thickness of the
structural body through which the opening runs, but in any case the two
terms are considered herein to be interchangeable.
[0067] Referring now to FIGS. 1-4, an optical signal multiplexing
apparatus, generally designated 10, is illustrated in accordance with
the present invention. Multiplexing apparatus 10 comprises an enclosure
12 mounted to a base 14. Two rows of apertures (see FIG. 3), generally
designated 16 and 18, respectively, are formed on a top surface 12A of
enclosure 12. Two corresponding rows of fiber optic cable ferrules or
fittings generally designated 21 and 23, respectively, (see FIG. 1) are
mounted in these apertures 16 and 18. Individual fiber-optic source
lines OSL.sub.1-OSL.sub.n (where, in the illustrated exemplary
embodiment, n=8) extend through the respective fittings of row 23 (and
apertures 18), and individual fiber-optic return lines
ORL.sub.1-ORL.sub.n extend through the respective fittings of the other
row 21(and apertures 16). In FIGS. 1 and 3, only the first pair of
optical source and return lines, optical source line OSL.sub.1 and
optical return line ORL.sub.1, are shown. In FIG. 2, the respective
bundles of optical source lines OSL.sub.1-OSL.sub.n and optical return
lines ORL.sub.1-ORL.sub.n are schematically depicted by large arrows to
indicate generally the direction of optical signals into and out from
multiplexing apparatus 10.
[0068] Portions of enclosure 12 are removed in FIGS. 1-4 to illustrate
the interior components disposed within enclosure 12. The primary
operative interior components are two rotary indexing devices. One
rotary device is referred to herein as an optical source line selector
device, generally designated 80, and the other rotary device is
referred to as an optical return line selector device, generally
designated 130.
[0069] Source and return line selector devices 80 and 130 are situated
adjacent to one another and are supported in fixed relation to each
other, for example, by two axially spaced mounting blocks 26 and 28
that extend upwardly from base 14. A ferrule or input fitting 31 is
connected to an input end of source line selector device 80. A circular
array of fittings, generally designated 33, are connected to an output
end of source line selector device 80. Another circular array of
fittings, generally designated 35, are connected to an input end of
return line selector device 130. A ferrule or output fitting 37 is
connected to an output end of return line selector device 130. A common
source line or input bus IB is connected to input fitting 31, and a
common return line or output bus OB is connected to output fitting 37.
As just described, each individual fiber-optic source line
OSL.sub.1-OSL.sub.n runs through a corresponding fitting 23 of aperture
row 18, and each individual return line ORL.sub.1-ORL.sub.nruns through
fittings 21 mounted to aperture row 16. Although not specifically shown
in FIG. 1 for clarity, each individual fiber optic source line
OSL.sub.1-OSL.sub.n is connected to a corresponding one of fittings 33
of source line selector device 80, and each individual return line
ORL.sub.1-ORL.sub.n is likewise connected to a corresponding one of
fittings 35 of return line selector device 130. As described more fully
below, source line selector device 80 functions to select which one of
the fiber-optic source lines OSL.sub.1-OSL.sub.n is optically coupled
to input bus IB over a given interval of time. Return line selector
device 130 functions to select which one of the fiber-optic return
lines ORL.sub.1-ORL.sub.n is optically coupled to output bus OB over
the same interval of time.
[0070] As best shown in FIGS. 3 and 4, multiplexing apparatus 10
further comprises a means for causing both source line selector device
80 and return line selector device 130 to rotate simultaneously and in
an indexing fashion. Preferably, the means is provided in the form of a
powered mechanism adapted to transfer rotational force through a force
transmission mechanism. In the exemplary embodiment illustrated in
FIGS. 1-4, the powered mechanism is a motor 40 (such as, for example, a
DC stepper motor) that causes a shaft 42 to rotate through programmed
increments. The transmission mechanism includes an arrangement of gear
wheels 45, 47 and 49. Gear wheel 45 is mounted to shaft 42 and thus
rotates about the axis of shaft 42. Gear wheel 47 is mounted to source
line selector device 80 and rotates about an axis L.sub.1 of source
line selector device 80 (see FIG. 4). Gear wheel 49 is mounted to
return line selector device 130 and rotates about an axis L.sub.2 of
return line selector device 130. Gear wheels 47 and 49 are disposed in
meshing engagement with gear wheel 45. Accordingly, clockwise rotation
of gear wheel 45 results in counterclockwise rotation of both gear
wheels 47 and 49. Conversely, counterclockwise rotation of gear wheel
45 results in clockwise rotation of both gear wheels 47 and 49.
Moreover, gear wheels 47 and 49 are similarly sized and have the same
number of teeth. As a result, rotation of gear wheel 45 through a given
incremental arc length causes rotation of both gear wheels 47 and 49
through another proportional incremental arc length. The arc length
through which gear wheel 47 rotates is the same as the arc length
through which gear wheel 49 rotates.
[0071] As appreciated by persons skilled in the art, multiplexing
apparatus 10 can be provided with means for verifying the positions of
the various rotating components. For example, primary position
verification can be effected by providing an optical encoder (not
shown) that is focused on shaft 42 of motor 40. As a secondary mode of
position verification, Hall effect sensors (not shown) can be provided
to interface with a magnet (not shown) mounted on each gear wheel 47
and 49 respectively associated with source line selector device 80 and
return line selector device 130. With respect to each source line
selector device 80 and return line selector device 130, each
corresponding set of Hall effect sensors would be mounted at each index
position, such as by mounting the sensors in a circular array on a
separate disks that rotates with corresponding barrel 85 or 135 in
parallel with the magnet mounted to corresponding gear wheel 47 or 49.
[0072] Referring now to FIGS. 5A-7C, details of source line selector
device 80 and return line selector device 130 are illustrated.
Referring specifically to FIG. 5A, source line selector device 80
comprises a rotary element or barrel 85 that is rotatable about its
central axis L.sub.1. Barrel 85 includes an outer lateral surface 85A,
an input end surface 85B, and an output end surface 85C. Gear wheel 47
is fitted around the periphery of outer lateral surface 85A. Gear wheel
47 is either a separate component or comprises teeth formed around
barrel 85. An internal bore 87 extends through the body of barrel 85,
and has an input bore end 87A opening at input end surface 85B and an
output bore end 87B opening at output end surface 85C. Input bore end
87A is coincident with axis L.sub.1, and thus the position of input
bore end 87A in relation to axis L.sub.1 does not change during
rotation of barrel 85. Output bore end 87B, on the other hand, is
disposed at a location on output end surface 85C that is offset from
axis L.sub.1 by a radial offset distance equal to radius R. Rotation of
barrel 85 about axis L.sub.1 therefore results in rotation of output
bore end 87B along a circular path of radius R, as defined on output
end surface 85C with respect to axis L.sub.1. An internal optical fiber
90 (see FIG. 6A) extends throughout internal bore 87. Internal optical
fiber 90 terminates at an input fiber end 90A (see FIG. 6A) located at
input bore end 87A, and terminates at an output fiber end 90B (see FIG.
6A) located at output bore end 87B. Thus, input fiber end 90A is
coincident with axis L.sub.1 and output fiber end 90B is offset from
axis L.sub.1 by radial offset distance (or radius) R. Rotation of
barrel 85 about axis L.sub.1 does not affect the position of input
fiber end 90A, but results in a circumferential change in the position
of output fiber end 90B with respect to axis L.sub.1. Referring to FIG.
6A, source line selector device 80 is designed to permit rotational
indexing of barrel 85 about axis L.sub.1. Through this rotational
movement, output fiber end 90B can be selectively positioned at one of
a plurality of equally spaced index locations around a circumference on
output end surface 85C. This circumference is swept out by the
conceptual end point of radius R in relation to axis L.sub.1. In order
to implement source fiber "channel" or line selection, barrel 85
rotates with respect to some type of stationary member that includes a
number of fixed-position optical reception points corresponding to the
plurality of index locations. In FIG. 6A, for example, the channel
selection is implemented according to the invention by providing a
stationary optical reception member. In the present embodiment, the
stationary optical reception member is a bearing sleeve or cap 95
disposed at the output side of barrel 85. A bearing 105 provides an
interface between rotatable barrel 85 and stationary bearing sleeve 95.
As illustrated in FIG. 6A, bearing 105 can be a roller bearing of
conventional design that includes an inner ring 105A, an outer ring
105B, and a series of balls 107 contacting the respective, opposing
raceways of inner ring 105A and outer ring 105B. As understood by
persons skilled in the art, balls 107 typically are interposed between
inner ring 105A and outer ring 105B and in a circumferentially spaced
arrangement through the use of a retaining element (not shown) forming
some type of frame, cage, or carriage around each ball 107. Inner ring
105A firmly contacts (such as by press fitting) lateral outer surface
85A of barrel 85, while outer ring 105B firmly contacts at least the
inner surface of an annular section 95A of bearing sleeve 95. By this
arrangement, inner ring 105A rotates with barrel 85 while outer ring
105B remains in a fixed position with stationary bearing sleeve 95. It
will be understood that bearing 105 could be either a ball bearing or a
needle bearing, or some other type of bearing that permits barrel 85 to
rotate in a stable manner with respect to bearing sleeve 95. That is,
rotatable needle elements could be substituted for balls 107
illustrated in FIG. 6A.
[0073] In addition to its annular section 95A, bearing sleeve 95
includes a plate section 95B transversely oriented with respect to axis
L.sub.1 of source line selector device 80. Plate section 95B is
immediately adjacent to output end surface 85C of barrel 85. Plate
section 95B includes a plurality of apertures 97 (only two of which are
shown in FIG. 6A) arranged in a circular array of radius R with respect
to axis L.sub.1. These apertures 97 constitute the previously described
fixed-position optical reception points. The actual number of apertures
97 corresponds to the number of indices at which output fiber end 90B
of internal optical fiber 90 can be selectively positioned, and
accordingly corresponds to the number of individual optical channels or
lines into which an optical signal traveling through internal optical
fiber 90 from input fiber end 90A can be selectively directed through
output fiber end 90B. The specific number of apertures 97 (and hence
the specific number of individual optical channels and index positions)
will depend on the number of test sites to which optical source signals
are to be sent. Besides the test sites that contain analytical samples,
one or more of these test sites could hold reference or control samples
(e.g., sources for obtaining blank or standard measurement data). In
the example shown in FIG. 7B, plate section 95B of bearing sleeve 95
includes an array of eight apertures 97 to handle eight separate
optical channels or lines. It will be understood, however, that more or
less apertures 97 could be provided, again depending on the number of
separate optical channels.
[0074] The specific provision of bearing 105 and bearing sleeve 95, in
the arrangement and design illustrated in FIG. 6A, ensures that any
light loss from the light conducting components of source line selector
device 80 is negligible. The size of the air gap between output end
surface 85C of barrel 85 and plate section 95B of bearing sleeve 95 is
preset to provide optimal light transmission. Annular section 95A and
plate section 95B of bearing sleeve 95 cooperatively form a shoulder
around bearing 105 and output end surface 85C to prevent light losses.
In furtherance of the purpose of preventing light loss in this
particular arrangement, it is preferable that the axial edges of inner
ring 105A and outer ring 105B of bearing 105 facing plate section 95B
of bearing sleeve 95 be substantially flush with output end surface 85C
of barrel 85.
[0075] Although source line selector device 80 and its barrel 85 are
not expected to encounter axial thrust forces during the operation of
multiplexing device 10, source line selector device 80 can further
include a second bearing 125 and corresponding bearing sleeve 115
mounted at the input side, as also shown in FIG. 6A. The design and
arrangement of input-side bearing 125 and bearing sleeve 115 can be
similar to those of output-side bearing 105 and bearing sleeve 95.
Input-side bearing sleeve 115 thus includes an annular section 115A and
a plate section 115B. As one principal difference, however, input-side
bearing sleeve 115 includes only one aperture 117 formed in its plate
section 115B (see also FIG. 7A). This single aperture 117 is situated
coincident with axis L.sub.1 and is immediately adjacent to input fiber
end 90A of internal optical fiber 90. The inclusion of input-side
bearing 125 and bearing sleeve 115 lends stability to the indexing
movements of barrel 85 and overall operation of source line selector
device 80, and further facilitates the optical coupling of internal
optical fiber 90 to input bus IB (see FIG. 1). Input-side bearing 125
can comprise balls 127 interposed between an inner ring 125A and an
outer ring 125B.
[0076] Referring to FIG. 5B, return line selector device 130 comprises
features similar to those of source line selector device 80 although,
as shown in FIG. 1, the axial positions of the input and output sides
of return line selector device 130 are reversed in comparison to those
of source line selector device 80. Specifically, return line selector
device 130 comprises a rotary element or barrel 135 rotatable about its
central axis L.sub.2. Barrel 135 includes an outer lateral surface
135A, an input end surface 135B, and an output end surface 135C. Gear
wheel 49 is fitted around the periphery of outer lateral surface 135A.
Gear wheel 49 is either a separate component or comprises teeth formed
around barrel 135. An internal bore 137 extends through the body of
barrel 135, and has an input bore end 137A opening at input end surface
135B and an output bore end 137B opening at output end surface 135C.
Input bore end 137A is disposed at a location on input end surface 135B
that is offset from axis L.sub.2 by a radial offset distance equal to
radius R. Rotation of barrel 135 about axis L.sub.2 therefore results
in rotation of input bore end 137A along a circular path of radius R
defined on input end surface 135B with respect to axis L.sub.2. Output
bore end 137B, on the other hand, is coincident with axis L.sub.2 such
that its position in relation to axis L.sub.2 does not change during
rotation of barrel 135. An internal optical fiber 140 extends
throughout internal bore 137. Internal optical fiber 140 (see FIG. 6B)
terminates at an input fiber end 140A located at input bore end 137A,
and terminates at an output fiber end 140B located at output bore end
137B. Thus, input fiber end 140A is offset from axis L.sub.2 by radial
offset distance (or radius) R and output fiber end 140B is coincident
with axis L.sub.2. Rotation of barrel 135 about axis L.sub.2 does not
affect the position of output fiber end 140B, but results in a
circumferential change in the position of input fiber end 140A with
respect to axis L.sub.2.
[0077] Referring to FIG. 6B, return line selector device 130 enables
rotational indexing of barrel 135 about axis L.sub.2 in a manner
analogous to source line selector device 80. Through the rotational
movement effected by return line selector device 130, its input fiber
end 140A can be selectively positioned at one of a plurality of equally
spaced index locations around a circumference of radius R defined on
input end surface 135B. In order to implement return fiber "channel" or
line selection, return line selector device 130 includes a stationary
bearing sleeve 145 disposed at the output side of barrel 135. As in the
case of source fiber selector device 80, barrel 135 rotates with
respect to bearing sleeve 145. A bearing 155 provides an interface
between rotatable barrel 135 and stationary bearing sleeve 145. Bearing
155 can be provided in the form of a roller bearing that includes an
inner ring 155A, an outer ring 155B, and a series of balls 157 or
needles according to conventional designs. Inner ring 155A rotates with
barrel 135 while outer ring 155B remains in a fixed position with
stationary bearing sleeve 145.
[0078] Bearing sleeve 145 of return line selector device 130 comprises
an annular section 145A coaxially disposed around bearing 155 and a
plate section 145B transversely oriented with respect to axis L.sub.2
of return line selector device 130. Plate section 145B is immediately
adjacent to input end surface 135B of barrel 135 with an air gap
therebetween, which is dimensioned for optimal optical transmission.
Annular section 145A and plate section 145B of bearing sleeve 145
cooperatively form a shoulder around bearing 155 and input end surface
135B. This arrangement of bearing 155 and bearing sleeve 145 ensures
that any light loss from the light conducting components of return line
selector device 130 is negligible. In furtherance of the purpose of
preventing light loss in this particular arrangement, it is preferable
that the axial edges of inner ring 155A and outer ring 155B of bearing
155 facing plate section 145B of bearing sleeve 145 be substantially
flush with input end surface 135B of barrel 135.
[0079] Plate section 145B includes a plurality of apertures 147 (only
two of which are shown in FIG. 6B) arranged in a circular array of
radius R with respect to axis L.sub.2. These apertures 147 constitute
fixed-position optical coupling points between the individual return
fibers ORL.sub.1-ORL.sub.n and input fiber end 140A of internal optical
fiber 140. The actual number of apertures 147 corresponds to the number
of indices at which input fiber end 140A can be selectively positioned,
and accordingly corresponds to the number of individual optical
channels or lines from which an optical signal can be selectively
directed into input fiber end 140A. The specific number of apertures
147 (and hence the specific number of individual optical channels and
index positions) will depend on the number of sites or detection areas
from which optical return signals are to be received.
[0080] As also shown in FIG. 6B, return line selector device 130 can
further include a second bearing 175 and corresponding bearing sleeve
165 mounted at the output side. The design and arrangement of
output-side bearing 175 and bearing sleeve 165 can be similar to those
of input-side bearing 105 and bearing sleeve 95. Output-side bearing
sleeve 165 thus includes an annular section 165A and a plate section
165B. Output-side bearing sleeve 165, however, includes only one
aperture 167 formed in its plate section 165B. This single aperture 167
is situated coincident with axis L.sub.2 and is immediately adjacent to
output fiber end 140B of internal optical fiber 140 and, on the other
side, to output bus OB (see FIG. 1). Output-side bearing 175 can
comprise balls 177 interposed between an inner ring 175A and an outer
ring 175B.
[0081] FIG. 7A illustrates plate section 115B and single aperture 117
of input-side bearing sleeve 115 of source line selector device 80.
FIG. 7B illustrates plate section 95B and multiple apertures 97 of
output-side bearing sleeve 95 of source line selector device 80. FIG.
7C illustrates input-side bearing sleeve 115, output-side bearing
sleeve 95, and bearings 105 and 125 assembled onto barrel 85 of source
line selector device 80. It will be understood that FIGS. 7A-7C are
likewise representative of the structure of return line selector device
130, but with the input and output sides reversed. That is, FIG. 7A
could represent plate section 165B and single aperture 167 of
output-side bearing sleeve 165 of return line selector device 130, and
FIG. 7B could represent plate section 145B and multiple apertures 147
of input-side bearing sleeve 145 of return line selector device 130.
Likewise, FIG. 7C can be considered as illustrating input-side bearing
sleeve 145, output-side bearing sleeve 165, and bearings 155 and 175
assembled onto barrel 135 of return line selector device 130.
[0082] According to another aspect of the invention, FIG. 8 illustrates
the general features of an analytical testing and data acquisition
system, generally designated 200, in which multiplexer apparatus 10 can
advantageously operate. In addition to multiplexer apparatus 10,
analytical testing system 200 comprises a light source, generally
designated 210, a data encoding or analytical signal generating system
or arrangement, generally designated 220, and an optical signal
receiving device or system generally designated 230.
[0083] Light source 210 can be any type of suitable continuous or
non-continuous optical source. Non-limiting examples include deuterium
arc lamps, xenon arc lamps, quartz halogen filament lamps, and tungsten
filament lamps. In one specific example, a pulsed light source such as
a xenon flash lamp could be employed to emit very short, intense bursts
of light. This type of lamp flashes only when acquiring a data point,
as compared to a diode array that exposes the sample to the entire
wavelength range with each reading and potentially causes degradation
of photosensitive samples. As described in commonly assigned U.S. Pat.
No. 6,002,477, because it emits light on a non-continuous basis, the
xenon flash lamp does not require a mechanical means such as a chopper
for interrupting the light beam during measurement of a dark signal.
One specific example of a xenon flash lamp that is capable of acquiring
eighty data points per second is employed in CARY.TM. Series
spectrophotometers commercially available from Varian, Inc, Palo Alto,
Calif.
[0084] Data encoding or analytical signal generating system 220 can
comprise any device or system adapted to contain and expose one or more
samples to the light energy supplied by light source in order to encode
information about that sample as the light passes through the sample
and the sample is irradiated. For example, data encoding system could
constitute an array of test sites F.sub.1-F.sub.n such as sample
measurement and/or holding sites. These test sites F.sub.1-F.sub.n can
be defined by a variety of sample measurement/containment components,
such as solid sample holders, sample containers or cells, test vessels,
flow cells, tanks, pipes, the wells of a quartz microtitre plate or
similar microcells capable of transmitting light, and specially
designed fiber-optic probes.
[0085] Signal receiving device or system 230 could be any type of
instrument or system of instruments adapted to receive and process the
optical signals supplied by data encoding device 220. The specific
property of the sample substance to be analyzed will dictate the type
of equipment or instrumentation used to analyze samples taken from, for
example, test vessels V.sub.1-V.sub.8 shown in FIG. 10. Moreover, the
various components comprising signal receiving device 230 will depend
on the type of analytical signal to be measured and detected. If the
desired analytical signal is the intensity of light radiation absorbed
by analytes at each test site F.sub.1-F.sub.n, absorbance values can be
calculated in order to determine the concentration of the target
substance (i.e., the analyte of interest). For this purpose, signal
receiving device 230 in FIG. 8 can comprise a UV-vis spectrophotometer.
The invention, however, is not limited to any specific design of
spectrophotometer. Possible configurations for the spectrophotometer
include those that utilize single detectors or multi-channel detectors,
those that are adapted to perform single-beam or double-beam
measurements, those that are adapted to perform horizontal-beam or
vertical-beam measurements, and those that can perform measurements of
fixed wavelength or of the entire absorption spectra for the sample.
Moreover, for the purpose of the present disclosure, the terms "signal
receiving device or system" and "sample analyzing system" are intended
to encompass any analyzing equipment compatible with the systems and
methods described herein. Such equipment may include, but is not
limited to, HPLC, spectrometers, photometers, spectrophotometers,
spectrographs, and similar equipment. In the case of a
spectrophotometer, signal receiving device 230 typically includes light
source 210, a wavelength selector or similar device, a radiation
detector such as a photoelectric detector or transducer, a signal
processor, and a readout device.
[0086] Referring to the schematic depiction of analytical testing and
data acquisition system 200 illustrated in FIG. 8, light source 210
optically communicates with source line selector device 80 of
multiplexing apparatus 10 via input bus IB, and optical signal
receiving device 230 optically communicates with return line selector
device 130 via output bus OB. In the present embodiment, data encoding
system 220 comprises a set of sample measurement components or test
sites F.sub.1-F.sub.n (e.g., flow cells, sample cells, test vessels, or
the like), each of which is adapted to contain or provide a target for
a sample to be analyzed. Source line selector device 80 optically
communicates with sample measurement components F.sub.1-F.sub.n via the
set of optical source lines OSL.sub.1-OSL.sub.n, respectively, and
return line selector device, 130 optically communicates with sample
measurement components F.sub.1-F.sub.n via a set of optical return
lines ORL.sub.1-ORL.sub.n, respectively. For clarity, only four each of
optical source lines OSL.sub.1-OSL.sub.n, sample measurement components
F.sub.1-F.sub.n, and optical return lines ORL.sub.1-ORL.sub.n are shown in FIG. 8. By this arrangement, each sample measurement component F.sub.1-F.sub.n can receive an incident light input of an initialintensity P.sub.0 from light source over a corresponding optical source line OSL.sub.1-OSL.sub.n, and subsequently transmit a light output of an intensity P to optical signal receiving device for processing and readout over a corresponding optical return line OSL.sub.1-OSL.sub.n. As described previously, respective internal optical fibers 90 and 140 of source and return line selector devices 80 and 130 are rotatably indexed in mutual synchronization. As a result, the selection of optical source line OSL.sub.1, for example, to carry the source signal from internal optical fiber 90 of source line selector device 80 to sample measurement component F.sub.1 concurs with the selection of optical return line ORL.sub.1 to carry the attenuated signal transmitted from sample measurement component F.sub.1 to internal optical fiber 140 of return line selector device 130.
[0087] Referring back to FIG. 3, some of the features of the system
described with reference to FIG. 8 are schematically shown in operative
communication with multiplexing apparatus 10. Light source 210
optically communicates with input bus IB, and output bus OB optically
communicates with signal receiving device 230. Sample measurement
component F.sub.1 optically communicates with optical source line
OSL.sub.1 and optical return line ORL.sub.1. In addition, sample
measurement component F.sub.1 is illustrated in the form of a liquid
phase-containing sample holding cell, and accordingly is illustrated as
fluidly communicating with a media sample line SL.sub.1 and a media
return line RL.sub.1. As described hereinabove, optical source line
OSL.sub.1 is connected to one of fittings 33 of source line selector
device 80, and optical return line ORL.sub.1 is connected to one of
fittings 35 of return line selector device 130. It will be understood
that other sample measurement components F.sub.2-F.sub.n can be
analogously interfaced with multiplexing apparatus 10 and other
corresponding media sample lines and media return lines (not shown).
[0088] The operation of sample analysis system 200 with sample cells
(e.g., sample cell or flow cell F.sub.1 as shown in FIG. 3) will now be
described. One or more samples of media are transferred from selected
test vessels (which could be, for example, mounted in a dissolution
test apparatus or other appropriate media preparation/testing
apparatus) through media sample lines (e.g., sample line SL.sub.1 in
FIG. 3) to corresponding sample cells F.sub.1-F.sub.n. After optical
measurements are taken, the samples can be, if the system is so
configured, returned to the test vessels through media return lines
(e.g., return line RL.sub.1 in FIG. 3). Calibration operations can also
be carried out prior to test runs as needed.
[0089] Multiplexing apparatus 10 is operated as described with
reference to FIGS. 1-7C. Preferably, the movements of multiplexing
apparatus 10 are coordinated with the operations of the other elements
of sample analysis system 200 under the control of a suitable
electronic processing device such as a computer (not shown).
Accordingly, source line and return line selector devices 80 and 130 of
multiplexing apparatus 10 are initially set to their respective home
positions. At the home positions, one of the bundle of optical fiber
source lines OSL.sub.1-OSL.sub.n is positioned (e.g., at "index
position 1") in optical coupling relation with optical input bus IB,
and a corresponding one of the bundle of optical fiber return lines
ORL.sub.1-ORL.sub.n is positioned (e.g., at a corresponding "index
position 1") in optical coupling relation with optical output bus OB.
In effect, multiplexing apparatus 10 selects the sample measurement
component F.sub.1-F.sub.n corresponding to the selected index position
of source and return selector devices 80 and 130.
[0090] To take a measurement of the sample residing in the selected
sample measurement component, light source 210 sends a beam of light of
intensity P.sub.0 into input bus IB. Source line selector device 80 is
positioned such that the light is routed into the selected one of the
bundle of source lines OSL.sub.1-OSL.sub.n. This source beam (or pulse)
is thus transmitted into the particular sample measurement component
F.sub.1-F.sub.n that corresponds to the selected source line
OSL.sub.1-OSL.sub.n and return line ORL.sub.1-ORL.sub.n. Light source
210 and the sample residing in the selected sample measurement
component can together be considered as a signal generator, in that
light source 210 and the sample conjoin to generate the analytical
signal in the form of an attenuated beam of light of intensity P as the
beam of light passes through the sample. The analytical signal is
transmitted through the selected one of return lines
ORL.sub.1-ORL.sub.n back to multiplexing apparatus 10 and, due to the
position of return line selector device 130, is routed into output bus
OB. Output bus OB transmits the analytical signal to signal receiving
device 230 for detection and processing, and the concentration of the
measured sample is determined from the value obtained from its measured
light absorbance, using calibration curves if necessary.
[0091] Within signal receiving device 230, a wavelength selector is
typically provided in the form of a filter or monochromator that
isolates a restricted region of the electromagnetic spectrum for
subsequent processing. The detector converts the radiant energy of the
analytical signal into an electrical signal suitable for use by the
signal processor. The signal processor can be adapted to modify the
transduced signal in a variety of ways as necessary for the operation
of signal receiving device 230 and the conversion to a readout signal.
Functions performed by the signal processor can include amplification
(i.e., multiplication of the signal by a constant greater than unity),
logarithmic amplification, ratioing, attenuation (i.e., multiplication
of the signal by a constant smaller than unity), integration,
differentiation, addition, subtraction, exponential increase,
conversion to AC, rectification to DC, comparison of the transduced
signal with one from a standard source, and/or transformation of the
electrical signal from a current to a voltage (or the converse of this
operation). Finally, a readout device displays the transduced and
processed signal, and can be a moving-coil meter, a strip-chart
recorder, a digital display unit such as a digital voltmeter or CRT
terminal, a printer, or a similarly related device.
[0092] As indicated previously, remote flow cells are but one type of
means for encoding information that can be processed by signal
receiving device 230. Other examples of sample measurement components
are fiber-optic probes, or dip probes, that are designed for insertion
directly into a container holding an analyte-containing media. In some
applications, the use of dip probes has been a substitute for the
removal (and preferably the subsequent return) of samples from the
media container and the transfer of the samples to the sample cell of a
spectroscopic or other sample analyzing apparatus.
[0093] Referring now to FIG. 9, an example of a dip probe of
conventional design, generally designated DP, is illustrated. In
typical use, dip probe DP is inserted into a test vessel V so that the
lower portion of its tip 371 is submerged in media held by test vessel
V, thereby allowing absorbance measurements to be taken directly in
test vessel V. Dip probe DP typically includes a detection area or
cavity 373 similar to a flow cell that is defined by a gap between a
fused silica or quartz lens or seal 375 and a mirror 377. Dip probe DP
is illustrated operating in conjunction with a spectrophotometer 380
that includes a light source 382 and a photodiode amplifier/detector
384. A first, light-transmitting fiber-optic cable 386 runs between
spectrophotometer 380 and glass seal 375. A second, light-returning
fiber-optic cable 388 runs between glass seal 375 back to
spectrophotometer 380, and usually includes an interference filter 391
or similar component. In use, a beam of light emitted by light source
382 is guided by first fiber-optic cable 386 along the direction of
arrow A into detection area 373. This beam of light passes through the
media residing in detection area 373, is reflected by mirror 377, and
thus is redirected into second fiber-optic cable 388 along the
direction indicated by arrow B. The light beam then passes through
interference filter 391 and returns to spectrophotometer 380 where the
signal is processed by detector 384. Preferably, the length of
detection area 373 is half the optical pathlength, as the light passes
through the solution twice before reaching detector 384.
[0094] Referring now to FIG. 10, an in-situ measurement system,
generally designated 400, is illustrated as a specific application of
analytical testing and data acquisition system 200 described
hereinabove with reference to FIGS. 3 and 8. In-situ measurement system
400 comprises multiplexer apparatus 10, light source 210, and optical
signal receiving device or system 230. In this particular embodiment of
the invention, in-situ measurement system 400 further provides a data
encoding device or analytical generating system in the form of an array
of dip probes DP.sub.1-DP.sub.8 or similar instruments that are
insertable into corresponding test vessels V.sub.1-V.sub.8. Hence,
sample measurements are taken directly in test vessels V.sub.1-V.sub.8.
One or more of vessels V.sub.1-V.sub.8, however, can serve as blank
and/or standard media vessels. Each dip probe DP.sub.1-DP.sub.8 is
connected to a corresponding pair of optical source lines
OSL.sub.1-OSL.sub.8 (indicated by solid lines) and return lines
ORL.sub.1-ORL.sub.8 (indicated by dashed lines). Source and return line
selector devices 80 and 130 of multiplexing apparatus 10 function in
the manner described hereinabove to selectively couple each source line
OSL.sub.1-OSL.sub.8 with input bus IB and each corresponding return
line ORL.sub.1-ORL.sub.8 with output bus OB. As in previously described
embodiments, light source 210 communicates with input bus IB and signal
receiving device 230 communicates with output bus OB. As one
alternative, each dip probe DP.sub.1-DP.sub.8 could be mounted to the
automated sampling assembly of a media preparation/testing apparatus
300, such that each dip probe DP.sub.1-DP.sub.8 could be inserted into
its vessel V.sub.1-V.sub.8 to take a measurement and thereafter removed
according to a programmed, automated schedule.
[0095] In addition to the use of sample containment means such as flow
cells, dip probes and the like as specified hereinabove, other means
and accessories can be employed for generating analytical data in
accordance with the invention. For example, instead of absorption
probes, reflectance probes can be employed for undertaking reflectance
measurements of samples. As appreciated by persons skilled in the art,
a typical reflectance probe includes two fiber-optic bundles. One
bundle forms a central core and delivers light to the sample. The other
bundle surrounds the central core, and collects the light reflected
from the sample and returns it to the detector of the associated sample
analyzing instrument. Alternatively, a transmission probe can be
employed to enable the measurement of solid samples. A typical
transmission probe includes two single optical fibers. One fiber
delivers light to the sample, and the other collects the light
transmitted through the sample and returns the transmitted light to the
sample analyzing instrument. The transmission probe is preferably used
in conjunction with a sample holder adapted to position the sample for
measurement. The nature of the sample (e.g., textile fabrics,
sunglasses) dictates the design of the sample holder. Transmittance
data can also be acquired from solid samples using an integrating
sphere, which is a hollow sphere having an internal surface that is a
non-selective diffuse reflector. Integrating spheres are often used to
measure the transmission of turbid, translucent, or opaque refractory
materials in situations where other techniques are inadequate due to
loss of light resulting from the scattering effects of the sample.
[0096] Referring back to FIGS. 1-3, while input bus IB can be directly
coupled to light source 210 and output bus OB directly coupled to
signal receiving device 230, this is not a requirement of the
invention. The invention contemplates that various accessories and
adaptations can be employed, such as those indicated hereinabove, and
that multiplexing apparatus 10 can be integrated with existing
analytical systems, in accordance with specific applications of
multiplexing apparatus 10. For example, in FIGS. 1-3, multiplexing
apparatus 10 can additionally include a fiber-optic coupling unit,
generally designated 425, for routing light beams into and out from
fiber-optic cables. Fiber-optic coupling unit 425 comprises an
enclosure 431, fittings 433 and 435 mounted to one or more walls of
enclosure 431, one or more internal optical mirrors 437 and 439 (see
FIG. 3) disposed within enclosure 431 and positioned at desired angles,
one or more apertures 441 and 443 (see FIGS. 1 and 2) formed in the
walls of enclosure 431, and various types of lenses (not shown) if
needed. The input end of input bus IB is connected to fitting 433, and
the output end of output bus OB is connected to fitting 435. As best
illustrated in FIG. 3, a source signal from light source 210 enters
enclosure 431 through aperture 441(see FIG. 1), is reflected off
internal mirror 437, and is diverted into input bus IB. A return signal
from output bus OB is reflected off internal mirror 439 and diverted
toward signal receiving device 230 through aperture 443 (see FIG. 1).
[0097] Referring now to FIGS. 11, 12A, and 12B, another analytical
testing and data acquisition system, generally designated 600, is
illustrated according to another embodiment of the present invention.
In some cases, it may be desirable to eliminate either the multiplexing
or the demultiplexing feature of the invention. Accordingly, this
embodiment provides an alternative multiplexing apparatus, generally
designated 10', in which return line selector device 130 has been
eliminated. Source line selector device 80 functions as described
hereinabove. In the present embodiment, multiplexing apparatus 10'
comprises an output bus mounting assembly 630. Output bus mounting
assembly 630 includes an output aperture 632 in which a lens 634 is
preferably disposed. Lens 634 can be situated at the terminal end of a
cylindrical collar 636 or other suitable means for retaining and
collecting optical return lines ORL.sub.1-ORL.sub.n in a fixed-position
bundle. In this embodiment, the bundle of optical return lines
ORL.sub.1-ORL.sub.n collected from, for example, aperture rows 16 or 18
(see FIGS. 2 and 3) is considered in effect to be a multi-channel
output bus for analytical testing system 600. The bundle of optical
return lines ORL.sub.1-ORL.sub.n could also include an extra test line
that is connected to a reference source. In FIG. 12A, for example, a
total of nine lines are illustrated. For another example, a 16-channel
system would have seventeen lines (again assuming one test line were
included). Output aperture 632 is optically aligned with the receiving
window of a sample detector SD or other similar analyzing device or
light-receiving component thereof.
[0098] In operation, a sample beam from light source 210 is directed
through input bus IB into the input side of source line selector device
80 in the manner described hereinabove. As also described hereinabove,
source line selector device 80 is indexed by motor 40, shaft 42, gear
wheels 45 and 47, and other associated components (see FIGS. 2 and 3)
so as to select one of optical source lines OSL.sub.1-OSL.sub.n. The
signal is transferred out from source line selector device 80 through
the selected optical source line OSL.sub.1-OSL.sub.n and associated
fitting of one of aperture rows 16 and 18 to the selected sample
container or other type of test site F.sub.1-F.sub.n of encoding system
220. The transmitted light beam P is then returned through the
corresponding one of optical return lines ORL.sub.1-ORL.sub.n, through
one of aperture rows 16 or 18, to output bus mounting assembly 630
where all optical return lines ORL.sub.1-ORL.sub.n are bundled at
output aperture 632. Transmitted light beam P emanating from selected
optical return line ORL.sub.1-ORL.sub.n is directed into the window of
sample detector SD. This window is large enough to receive light from
any of the ends of optical return lines ORL.sub.1-ORL.sub.n bundled at
output bus mounting assembly 630. As an example, the window can be
approximately 1 cm.sup.2 in area, and the fiber ends of optical return
lines ORL.sub.1-ORL.sub.n can be positioned approximately 0.5 cm away
from the window.
[0099] It will be noted that multiplexing apparatus 10', in which
either source line selector device 80 or return line selector device
130 is eliminated, and either including or not including the other
features of spectrophotometer 600, can be integrated into the various
systems of the invention described with reference to FIGS. 3, 8 and 10
in the place of multiplexing apparatus 10.
[0100] It is therefore seen from the foregoing description that the
present invention provides a number of systems, devices, and methods
benefiting from the use of fiber-optics coupled with sample measurement
systems. The embodiments described herein result in high-quality
analysis and quantification of analytical samples with decreased
effort, and enable the efficient and controlled selection and routing
of optical signals and signal paths with minimal light loss.
[0101] It will be understood that the spectrophotometers described
hereinabove are generally of the type involving the transmission
measurement of a sample, wherein a light beam passes through a sample
cell or flow cell containing the sample to be analyzed. The invention,
however, is equally applicable to spectrophotometers of the type in
which the sample to be analyzed is subjected to reflectance measurement
and consequently do not necessarily require a sample cell or flow cell
for operation.
[0102] It will be understood that the embodiments described hereinabove
can be modified without undue effort to utilize more than one
multiplexing apparatus 10 or 10', light source 210, signal receiving
device 230 or SD, and/or set F of sample measurement components.
[0103] It will be further understood that various details of the
invention may be changed without departing from the scope of the
invention. Furthermore, the foregoing description is for the purpose of
illustration only, and not for the purpose of limitation-the invention
being defined by the claims.
Received on Tue Sep 27 2005 - 01:06:38 CDT
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