Abstract: An apparatus for carrying out Raman spectroscopy on a sample includes a light source for providing a beam of excitation radiation, and an optical system including a spectrograph. The spectrograph includes a grating that divides a beam of scattered light into a spectrum of spatially separated wavelength components and to direct a portion of the spectrum to a detector. The spectrograph includes: 1) a first lens system for focusing the portion of the spectrum onto the detector and 2) a second lens system-configured to provide a focal plane with focal point in the optical path for focusing the beam of excitation radiation and/or the beam of scattered radiation at the focal point. The apparatus including a reference sample arranged in the focal plane, in particular at the focal point, for obtaining a reference spectrum from the reference sample.

Abstract: The present invention relates to a particle therapy apparatus used for radiation therapy. More particularly, this invention relates to a gantry for delivering particle beams which comprises means to analyse the incoming beam. Means are integrated into the gantry to limit the momentum spread of the beam and/or the emittance of the beam.

Abstract: An apparatus reduces optical damage on an optical element that interacts with a light beam. The apparatus includes: an optical system configured to interact with a light beam to perform a modification to one or more aspects of the light beam, an alignment system, and an actuator. The optical system comprises at least one optical element having a surface configured to interact with the light beam, the surface being continuous and non-diffuse. The alignment system is configured to align the light beam relative to the optical element surface so that the light beam interacts with the optical element while the light beam is traveling at a first beam direction relative to the surface of the optical element and the light beam is outputted from the optical element along a second beam direction relative to the surface of the optical element after the light beam and optical element have interacted.

Abstract: An egg identification system for determining viability of an avian egg is provided. Such a system includes an emitter assembly configured to emit electromagnetic radiation toward an egg. A detector assembly is axially aligned with the emitter assembly to detect electromagnetic radiation transmitted through the egg. The detector assembly is spaced-apart from the egg during operation thereof such that the detector assembly does not contact the egg. The detected electromagnetic radiation is processed using transmission spectroscopy analysis to determine whether the egg is viable. An associated method is also provided.

Abstract: Apparatus for spectroscopic analysis which includes a tunable diode laser spectrometer having a digital output signal and a digital computer for receiving the digital output signal from the spectrometer, the digital computer programmed to process the digital output signal using a multivariate regression algorithm. In addition, a spectroscopic method of analysis using such apparatus. Finally, a method for controlling an ethylene cracker hydrogenator.

Abstract: In an optical path control device, a light input section 1 forms optical apertures 61a, 61b to output dispersed beams L2a, L2b, respectively, so that propagation angles of the dispersed beams L2a, L2b in an YZ plane are different from each other, at a focal position on the dispersive element 5 side of an optical power element 6. The dispersed beams L2a, L2b propagating at their respective angles different from each other in the YZ plane are individually coupled to optical deflectors 7a, 7b, respectively.

Abstract: Exemplary embodiments are directed to characterizing a solid state photomultiplier (SSPM). The SSPM can be exposed to a light pulse that triggers a plurality of microcells of the SSPM and an output signal of the SSPM generated in response to the light pulse can be processed. The output signal of the SSPM can be proportional to a gain of the SSPM and a quantity of microcells in the SSPM and a value of an electrical parameter of the SSPM can be determined based on a relationship between the output signal of the SSPM and an over voltage applied to the SSPM.

Abstract: A spectral measurement device includes: an optical band-pass filter section that has first to n-th wavelengths (n is an integer of 2 or more) having a predetermined wavelength width as a spectral band thereof; a correction operation section that corrects a reception signal based on an output optical signal from the optical band-pass filter section; and a signal processing section that executes predetermined signal processing based on the reception signal corrected by the correction operation section that corrects the reception signal based on the change in the spectral distribution of the reception signal.

Abstract: A wavelength selective switch utilizing aperture-shared optics and functionally distinct planes of operation that enables high fiber port counts, such as 1×41, and multiplicative expansion, such as to 1×83 or 1×145, by utilizing elements optimized for performance in one of the functionally distinct planes of operation without affecting the other plane.

Abstract: An analysis system, tool, and method for performing downhole fluid analysis, such as within a wellbore. The analysis system, tool, and method provide for a tool including a spectroscope for use in downhole fluid analysis which utilizes an adaptive optical element such as a Micro Mirror Array (MMA) and two distinct light channels and detectors to provide real-time scaling or normalization.

Abstract: An apparatus and a method for optically analyzing a sample are provided. The apparatus includes a first optical device that transmits a narrow waveband of light and has a first filter and a first monochromator that provide different paths for the narrow waveband of the light. The apparatus may also include a light source that generates the light as broadband excitation light, in which case the first optical device transmits a narrow waveband of the broadband excitation light through the first filter or the first monochromator. Further, the apparatus may include a second optical device that directs the narrow waveband of the broadband excitation light onto the sample and receives emission light from the sample, a third optical device that transmits a narrow waveband of the emission light, and a detector that converts the narrow waveband of the emission light into an electrical signal.

Abstract: A spectrophotometer includes a plurality of LEDs arranged in a circular array, each having a calibrated power input determined by the use of pulse width modulation and each having a unique wavelength band determined by the utilization of a unique fluorescent phosphor coating or lens. At least one of the LEDs comprising a phosphor-free high energy UV LED. Light reflected to the spectrophotometer is divided into predetermined wavelength ranges through the utilization of a linear variable filter and photo detectors wherein the analog signal from a photo detector is converted to a digital value through the use of auto-ranging gain technique.

Abstract: An analysis system, tool, and method for performing downhole fluid analysis, such as within a wellbore. The analysis system, tool, and method provide for a tool including a spectroscope for use in downhole fluid analysis which utilizes an adaptive optical element such as a Micro Mirror Array (MMA) and two distinct light channels and detectors to provide real-time scaling or normalization.

Abstract: An analysis system, tool, and method for performing downhole fluid analysis, such as within a wellbore. The analysis system, tool, and method provide for a tool including a spectroscope for use in downhole fluid analysis which utilizes an adaptive optical element such as a Micro Mirror Array (MMA) and two distinct light channels and detectors to provide real-time scaling or normalization.

Abstract: An object recognition device for a vehicle includes a size determining means, an existence condition determining means, and an adverse condition determining means. The size determining means determines that the recognized objects are large when a size of the objects is larger than a given determination value. The existence condition determining means determines whether at least a given number of the objects are determined to be large by the size determining means. The adverse condition determining means identifies an adverse condition related to recognizing the objects when at least the given number of the objects are determined to be large by the existence condition determining means.

Abstract: An apparatus and method are provided to verify the composition of a medical fluid in a fluid container. The verification is performed at a centralized location, where light is transmitted through the fluid and detected by a sensor that generates signals representative of the spectral data of the actual composition of the fluid. These signals are compared with the spectral data of an expected composition of the fluid. Based on the comparison, a label is generated that identifies the composition of the fluid and is affixed to the fluid container. The fluid container, with the verified fluid, is distributed to the point of care.

Abstract: An apparatus and method are provided to verify the composition of a medical fluid in a fluid infusion channel by comparison with clinician-entered input. Light is transmitted through the channel and detected by a sensor that generates signals representative of the spectral data of the light detected. A processor compares the spectral data of the light detected to the spectral data associated with the expected contents of the channel to verify that the correct fluid is being infused.

Abstract: A spectrometer system includes a thermal light source for illuminating a sample, where the thermal light source includes a filament that emits light when heated. The system additionally includes a spectrograph for measuring a light spectrum from the sample and an electrical circuit for supplying electrical current to the filament to heat the filament and for controlling a resistance of the filament. The electrical circuit includes a power supply that supplies current to the filament, first electrical components that sense a current through the filament, second electrical components that sense a voltage drop across the filament, third electrical components that compare a ratio of the sensed voltage drop and the sensed current with a predetermined value, and fourth electrical components that control the current through the filament or the voltage drop across the filament to cause the ratio to equal substantially the predetermined value.

Abstract: A detecting device for a spectrophotometer is provided which is capable of exhibiting a sufficient sensitivity and with an adequate linearity over the ultraviolet light, visible light and near-infrared light ranges. The spectrophotometer detecting device includes detectors of a photomultiplier-tube detector, an InGaAs detector and a PbS detector, and a switching device for switching among these detectors. Alternatively, the spectrophotometer may include a single integrating sphere including these three types of detectors placed thereon. The spectrophotometer may further include output conversion means for correcting the output linearity difference among these detectors.

Abstract: In order to improve spectral measurement accuracy during high-speed wavelength shifting, the appropriate sensitivity of the detection system is maintained by, prior to measurement of a sample, measuring the voltage value, then storing this value into a table, and maintaining the voltage value to be applied to the photodetector, and during measurement of the sample, reading out the maintained voltage value and applying it to the photodetector.

Abstract: An optical system for determining an optical constant by measuring the absolute reflectance and the absolute transmittance of a substance by using an incoming side beam switching mirror for selectively switching the direction of a light from a light source to first or second converged light reflecting units. The first and second converged light reflecting units project the light from the beam switching mirror so as to be converged in an intersecting manner at the position of a sample holder that can be positioned to present a sample fitting hole or a through hole for measuring the reflectance/transmittance by providing the light to an exit side beam switching mirror and detector.

Abstract: A modular dual-beam source, sample compartment and beam-combining system are provided when used with a monochromator and detector to form a spectrophotometer consisting of: (a) a source module where two ellipsoidal mirrors each produce an image of the light source, and (b) a reflecting sample-compartment module, wherein each side has two plane-mirrors, of the four plane mirrors, three are reference and one is the sample, or (c) a transmission sample-compartment module, wherein each side has two plane-mirrors, and a sample is placed between one pair of plane-mirrors, and (d) a beam-combining module wherein the source images are imaged by a second pair of ellipsoidal mirrors on a reflective chopper that combines the images at a single location that is imaged, external to the module, by another mirror, each module being kinematically located with respect to each other so the system remains optically aligned as modules are interchanged.

Abstract: An illumination subsystem for use in optical analysis which provides spatially and angularly homogenized radiation to the sample being analyzed. The system eliminates the illumination system as an interferent in the overall optical analysis. Thus, modest translations or rotations of the illumination source or changing the illumination source does not require recalibration of the instrument or prior modeling of illumination variability due to such changes. Illumination stability is achieved by incorporating a light pipe which both angularly and spatially homogenizes the light. Further, a series of filters and/or lenses are incorporated to provide bandpass filtering which eliminates unwanted wavelengths or bands of wavelengths from contacting the tissue and allows for a higher signal-to-noise ratio when the sample is tissue, while preventing thermal damage.

Abstract: An apparatus for flash photolysis has a light source and an optical fiber for directing light from the light source and through a sample. A laser or other such device is provided for initiating a chemical change within the sample. Additionally, a device is provided for determining the change in absorption of light by the sample during the chemical change.

Abstract: An optical measuring arrangement, particularly for quality control in continuous material flow processes, comprising a measuring head which is arranged immediately adjacent to a measurement object, a measurement light source which is held at the measuring head for illuminating a measurement spot on the measurement object, a measurement light reception device, at least one spectrometer which is optically coupled with the measurement light reception device via a light-conducting device, wherein the spectrometer and the light-conducting device are received in the measuring head, and a signal processing device which is likewise received in the measuring head. This results in a compact arrangement for reflection measurement which is easy to assemble and which, beyond this, supplies very accurate measurement results. Further, a measuring arrangement operating on the principle of spectroscopy is suggested for transmission measurement.

Abstract: Atom absorption spectroscopy method generates at least one first beam of monochromatic radiation at a certain wavelength. Radiation is separated into a test beam and a reference beam, and only the test beam is led through a test area. Subsequently, both beams pass through a slot system into a monochromator, and after their spectral breakdown, reach a detector system. In order to improve such atom absorption spectroscopy method in a way that allows the test beam and the reference beam as well as their spectra to be guided close to, or adjacent to one other onto the detector system, and, at the same time enables a simple and easy adaptation of the spectrometer's effective spectral range to a monochromator's characteristics, the test beam and the reference beam thus pass through different slots in the slot system and are projected onto essentially spatially separate areas of the detector system, with their spectra's broken-down.

Abstract: In a double beam spectrophotometer, a sample beam is irradiated to a large-sized sample in a substantially vertical direction, and the beam upwardly transmitted through the large-sized sample is reflected by a reflecting mirror and sent to an integrating sphere including a detector. A reference beam irradiated parallel to the sample beam is deflected by reflecting mirrors such that the reference beam goes around the large-sized sample, and guided to the integrating sphere. Thus, a holder is not required to correspond to a size or shape of the sample, and measurement position can be freely changed by moving the sample. Also, in case of utilizing a conventional standard sample chamber, movable reflecting mirrors are inserted in the optical paths to transfer the beams to the standard sample chamber.

Abstract: In a spectrophotometer, light emitted from a light source is processed to provide monochromatic light by a monochromator, and reaches a sector mirror having a chopper function. The sector mirror is rotated by a motor, and a rotational frequency of the motor can be controlled by a controller. By rotation of the sector mirror, monochromatic light is alternately distributed to a sample cell and a reference cell through a mirror. In measuring a wavelength range where a detector having a photomultiplier with a fast response speed is used, the motor is rotated at a high speed, so that time for scanning a wavelength is shortened. In measuring a wavelength range where a detector having lead sulfide with a slow response speed is used, the motor is rotated at a low speed to obtain a sufficiently strong signal intensity. Accordingly, in the spectrophotometer, the analysis time can be shortened, and the sufficiently strong signal can be outputted at the same time.

Abstract: A spectrometer (1) for reflection measurement contains a rotatable mirror arrangement (5) which is movable about an optical axis (21) between at least one measuring location (12) and a reference position (10), so that the measuring and reference conditions are largely identical. The rotatable mirror arrangement (5) and the reference sample(s) are arranged in a closed housing (13). The measuring samples (11) are placed on a receiving location (15) on the outer wall (14) of the housing (13). The spectrometer (1) with a rotatable mirror arrangement (5) may be applied for multiple referencing.

Abstract: An apparatus for the spectroscopic analysis of the composition of the contents of vessels, especially of conduits, by recording transmission spectra is described. The apparatus comprises at least a radiation source for generating the measuring radiation, and a spectral analyzer for measuring the transmitted radiation, two windows which are disposed opposite one another on the vessel and are transparent to the measuring radiation, and two collimators which are designed to spread the measuring radiation within the range of the measuring section and are disposed opposite one another in front of the windows, characterized in that the collimators are positioned relative to one another in a mounting joined to the vessel and the collimators can, while their relative alignment is maintained, be swung out in parallel from the range of the measuring section in the vessel or be displaced and/or be fixed to the mounting, so that the measuring section bypasses the vessel.

Abstract: In a spectrophotometer, light emitted from a light source is processed to provide monochromatic light by a monochromator, and reaches a sector mirror having a chopper function. The sector mirror is rotated by a motor, and a rotational frequency of the motor can be controlled by a controller. By rotation of the sector mirror, monochromatic light is alternately distributed to a sample cell and a reference cell through a mirror. In measuring a wavelength range where a detector having a photomultiplier with a fast response speed is used, the motor is rotated at a high speed, so that time for scanning a wavelength is shortened. In measuring a wavelength range where a detector having lead sulfide with a slow response speed is used, the motor is rotated at a low speed to obtain a sufficiently strong signal intensity. Accordingly, in the spectrophotometer, the analysis time can be shortened, and the sufficiently strong signal can be outputted at the same time.

Abstract: In a double beam spectrophotometer, a sample beam is irradiated to a large-sized sample in a substantially vertical direction, and the beam upwardly transmitted through the large-sized sample is reflected by a reflecting mirror and sent to an integrating sphere including a detector. A reference beam irradiated parallel to the sample beam is deflected by reflecting mirrors such that the reference beam goes around the large-sized sample, and guided to the integrating sphere. Thus, a holder is not required to correspond to a size or shape of the sample, and measurement position can be freely changed by moving the sample. Also, in case of utilizing a conventional standard sample chamber, movable reflecting mirrors are inserted in the optical paths to transfer the beams to the standard sample chamber.

Abstract: For conversion of spectral information of an FTIR spectrometric instrument for comparison with that of a dispersion instrument, a first standard function is selected for spectral line shape for the first instrument, and a second standard function for line shape is selected for the second instrument. A conversion factor is computed for converting the first standard function to the second standard function. In ordinary operations, first spectral information is obtained with the first instrument for a first sample, and second spectral information is obtained with the second instrument for a second sample. The conversion factor is applied to the first spectral information to effect converted information, and the converted information is compared with the second spectral information. Such conversion also is applied between chromatographic instruments.

Abstract: An integrated dual beam multi-channel optical-based flux monitor and method of monitoring atomic absorption of a plurality of atomic species during epitaxial growth. Light from multiple sources is simultaneously passed through a region of deposition of material such that atomic absorption takes place. The light that passed through the region is then compared to light in a reference arm that did not pass through a region of atomic absorption. From this comparison the growth of an epitaxial layer can be carefully controlled.

Abstract: The spectroscopic process uses a detector in the form of a linear array of detector units made of a photoconductive semiconductor material, wherein a radiation sample is broken down into its spectrum; the spectrum thus obtained is used to illuminate the detector and is evaluated making use of the dependence of the conductivity of the semiconductor material on the radiation intensity; the beam path between the sample and the detector is periodically interrupted by a chopper to generate dark and bright phases; when at least one measuring cycle is conducted, a measuring cycle is determined during both the dark and bright phases in one measuring period, and the intensity of the radiation impinging on the detector in the bright phase is found from the comparison between the dark phase and light phase; the interruptions in the radiation and the measuring periods are mutually synchronized so a measuring period lies either within a bright or within a dark phase, with the measuring period being variable and adjustable

Abstract: Standardization is achieved for FTIR spectrometric instruments that effect an intrinsic distortion in spectral information, the distortion being associated with an aperture size. An idealized function of spectral line shape is specified. With a small calibration aperture, spectral data is obtained for a basic sample having known "true" spectral data, and standard spectral data also is obtained for a standard sample. With a larger, normal sized aperture, standard spectral data is obtained again for the calibration sample. A transformation factor, that is a function of this data and the standardized function, is applied to spectral data for test samples to effect standardized information. In another embodiment, the standard sample has known true spectral data, and the basic sample is omitted. In either case, the transformation factor is applied to the sample data in logarithm form, the antilogarithm of the result effects the standardized information.

Abstract: A multi-channel type spectro-photometer not only has a light source, a sample cell to which light from the light source is directed, a spectrometer to which light transmitting through the sample cell is directed, and an array of photo-diodes to which dispersed light from the spectrometer is directed, but also allows the user to specify a range of wavelength within which measurements are to be taken. An optimum charge-accumulating time during which charge is to be accumulated on the photo-diodes array is automatically set according to the range specified by the user. Alternatively, quantity of light received by the photo-diode array may be detected and an optimum charge-accumulating time may be automatically set according to the measured light intensity on the photo-diode array. Dark current and background measurements are taken before a sample is injected into the sample cell and transmitted light therethrough is measured to obtain the absorption spectrum of the sample.

Abstract: A method and apparatus for instantaneously measuring the level of carbon dioxide (and other gases) in automotive combustion exhaust analysis is provided in the form of a portable battery driven roadside diagnostic instrument in which the CO.sub.2 level is measured by a calorimetric technique utilizing light as the energy source and a piezoelectric bimorph to vibrate a single fiber-optic element to multiplex between two fiber-optic receptors delivering the light to a measurement cell and a reference cell. The measurement cell comprises a salt of an acid-base indicator dye which provides proportional color change on contact with CO.sub.2. The dye is supported on a polymetric film in the cell.

Abstract: A double-beam spectrophotometer of the invention is provided with a sector mirror used at a luminous flux separating portion or at a luminous flux combining portion, and a DC brushless motor is used for actuating the sector mirror to rotate. Since the DC brushless motor is used, the sector mirror can be rotated at high speed with few noise. Also, the double-beam spectrophotometer can measure the change in the short period of time.

Abstract: A dual beam spectophotometer is described in which a beamsplitter is at least partially surrounded by a chopper, the combination of which provide sample and reference beams. An oscillating grating produces a monochromatic light beam scans a selected spectral range of wavelengths. The movement of a second chopper and of the oscillating grating is controlled to alternately pass sample and reference spectrums for detection by a detector and to block all radiation. Detected signals are processed for storage by suitable electronics and a computer. The electronics also control the motion of the oscillating grating and chopper. A set of beamsplitters with distinctly different sample-to-reference beam ratios are provided to add versatility to the spectrophotometer.

Abstract: A dual beam tunable spectrometer comprises a radiation source, generating means, a detector, and a shutter arrangement. The radiation source generates an incident radiative beam. The generating means, which includes an acousto-optic tunable filter, receives the incident radiative beam and generates therefrom a reference beam and a sample beam. The detector detects at least part of the reference beam, and detects at least part of the sample beam emitted from a sample following illumination of the sample with the sample beam. The shutter arrangement includes a first shutter selectively permitting passage therethrough of the part of the reference beam and a second shutter selectively permitting passage therethrough of the part of the sample beam. The shutter arrangement opens the first shutter and closes the second shutter to permit the detector to detect only the part of the reference beam.

Abstract: An apparatus, using two acousto-optical tuned filters for determining the wavelength and angle of approach of a light wave.

Abstract: A spectrometric instrument which exhibits an intrinsic profile for a sharp spectral line produces profile data for narrow spectral lines. The spectral lines are effected with a high finesse etalon of gold coated polymer. A transformation filter is computed for transforming the profile data to a gaussian profile. A wavelength calibration is combined with the filter to effect a correction matrix which is applied to sample data to generate calibrated standardized data. Iteratively a correction matrix is applied to calibration data to generate standardized calibration data which is utilized for the wavelength calibration. Calibration is effected with an optical standard, an interference etalon and a fringe formula. Etalon effective thickness is first estimated and then precisely determined so that fringe peaks calibrate wavelength.

Abstract: A high resolution infrared densitometer system is described which comprises an intense thermal light source, an optical system for projecting first and second images of the light source along respective parallel first sample and second reference optical axes, adjustable optical attenuators for selectively balancing the light intensity of the images projected along the sample and reference axes at selected optical density, a spectrometer for filtering background radiation from the projected images except for a selected wavelength, and a detector for measuring intensities of the filtered projected images. A method for making optical density measurements is described.

Abstract: The present invention is an apparatus for measuring the constituent concentration of a specimen on the basis of the color change in a test material housed in a test piece, which has reacted because of the specimen. The apparatus irradiates the test material which is a test piece loaded in the apparatus's main body and detects the intensity of the light reflected by the test material. A detection signal detected in the above way is sampled in a time period before and after the measurement timing at which the test material changes in color because of the specimen. An average value of the sampled detection signals is determined. The constituent concentration of the specimen is computed by referring to a stored conversion table on the basis of the average value determined in the above way.

Abstract: A process is provided for obtaining spectral information and quantifying the physical properties of a sample. The process comprises launching polychromatic light having a wavelength ranging from about 100 nanometers to about 2500 nanometers alternately through at least one sample channel and at least one reference channel, through at least one high-efficiency fiber optic switch. The sample and the polychromatic light along the sample channel are directed to a sample cell wherein the polychromatic light is passed through the sample, producing sample spectral information. The polychromatic light directed along the reference channel produces reference spectral information.

Abstract: An apparatus is provided for obtaining spectral information and quantifying the physical properties of a sample. The apparatus comprises a light source and a high-efficiency fiber optic switch means communicating with the light source for directing the light alternatively along at least two channels, the two channels comprising at least one reference channel and at least one sample channel. A sample means communicates with the sample channel for providing an interface between the light and the sample. A fiber optic means comprising a high-efficiency fiber optic switch and/or an optical coupler communicates with the sample channels and the reference channels and directs the light alternatively from the reference and sample channels to a mode scrambler. A wavelength discrimination device separates the light from the mode scrambler into component wavelengths and provides spectral information for the determination of the physical properties of the sample.

Abstract: Spectrophotometric apparatus and methodology suitable for continuous and long-term use. The apparatus includes a monochromator providing pre-dispersed monochromatic light to the optical inputs of a pair of fiber optic cables and a translator for alternatively positioning the fiber optic cables at the same location with respect to the monochromator output. One of the cables conducts light to a sample under study while the other cable provides a reference for light intensity measurements. The methodology includes the steps of performing two scans through the monochromator output for each measurement on the sample. The fiber optic cables are moved between scans so that the cable employed in the latter scan occupies the former position of the cable employed in prior scan.

Abstract: A positioning mechanism support structure mounted for movement between first and second predetermined positions in a spectroanalytical system includes relative to a reference member by a plurality of stabilizing coupling assemblies, and drive structure for producing motion of the support structure relative to the reference structure between first and second stop structures that define the first and second predetermined positions, respectively. Interlock structure responds to the drive force generated by the drive structure and de-energizes the drive structure in response to the drive force applied to that support structure exceeding a predetermined threshold value.

Abstract: An on-line, fiber-optic based apparatus for monitoring the concentration of a chemical substance at a plurality of locations in a chemical processing system comprises a plurality of probes, each of which is at a different location in the system, a light source, optic fibers for carrying light to and from the probes, a multiplexer for switching light from the source from one probe to the next in series, a diode array spectrophotometer for producing a spectrum from the light received from the probes, and a computer programmed to analyze the spectra so produced. The probes allow the light to pass through the chemical substance so that a portion of the light is absorbed before being returned to the multiplexer. A standard and a reference cell are included for data validation and error checking.