Abstract: Heterodyne interferometry is combined with spectrally-controlled interferometry (SCI) to achieve the advantages of both. Phase shifts produced by SCI produce phase-shifted correlograms suitable for heterodyne interferometric analysis, thereby enabling interferometric measurements with conventional common-path apparatus free of coherence noise and scanning-related errors, and with the precision of conventional heterodyne interferometry. A spectrum-modulating light source suitable for the invention is obtained by combining a rotating spiral grating with a multi-slit grating placed in the front focal plane of a collimating lens that propagates the light toward a blazed diffraction grating. Another exemplary spectrum-modulating light source is obtained by combining a slit spectrometer with an acousto-optic modulator.

Abstract: A spectroscopic sensor 1 comprises an interference filter unit 20, having a cavity layer 21 and mirror layers 22, 23 opposing each other through the layer 21, for selectively transmitting therethrough light in a predetermined wavelength range according to an incident position thereof; a light-transmitting substrate 3, arranged on the layer 22 side, for transmitting therethrough light incident on the unit 20; and a light-detecting substrate 4, arranged on the layer 23 side, for detecting the light transmitted through the unit 20. The layer 21 has a filter region 24 held between the layers 22, 23; an annular surrounding region 25 surrounding the region 24 with a predetermined distance therefrom; and an annular connecting region 26 connecting an end part 24e on the substrate 4 side of the region 24 and an end part 25e on the substrate 4 side of the region 25 to each other.

Abstract: An optical emission spectroscopic (OES) instrument includes a spectrometer, a processor and an adjustable mask controlled by the processor. The adjustable mask defines a portion of an analytical gap imaged by the spectrometer. The instrument automatically adjusts the size and position of an opening in the mask, so the spectrometer images an optimal portion of plasma formed in the analytical gap, thereby improving signal and noise characteristics of the instrument, without requiring tedious and time-consuming manual adjustment of the mask during manufacture or use.

Abstract: An X-ray apparatus that creates a virtual source having a narrow energy bandwidth and enables a high-resolution X-ray diffraction measurement; a method of using the same; and an X-ray irradiation method are provided. An X-ray apparatus 100 includes a monochromator 105 that focuses a divergent X-ray beam while dispersing it and a selection part 107 that is installed in a condensing position of the condensed X-ray beam for selecting an X-ray beam having a wavelength in a specific range, allowing it to pass through, and creating a virtual source. With this arrangement, it is possible to create a virtual source having a narrow energy bandwidth at a focal point 110 and by means of the virtual source a high-resolution X-ray diffraction measurement is available. By using the X-ray apparatus 100, it is possible to sufficiently separate an X-ray beam having such an extremely narrow energy bandwidth as, for example, K?1 ray from K?2 ray.

Abstract: A system or method for analyzing a sample include an input light source, a double subtractive monochromator positioned to receive light from the input light source and to sequentially illuminate the sample with each of a plurality of wavelengths, a multi-channel fluorescence detector positioned to receive and substantially simultaneously detect multiple wavelengths of light emitted by the sample for each of the plurality of excitation wavelengths, an absorption detector positioned to receive and detect light passing through the sample, and a computer in communication with the monochromator, the fluorescence detector, and the absorption detector, the computer controlling the monochromator to sequentially illuminate the sample with each of the plurality of wavelengths while measuring absorption and fluorescence of the sample based on signals received from the fluorescence and absorption detectors.

Abstract: A fast switching arbitrary frequency light source for broadband spectroscopic applications. The light source may operate near 1.6 um based on sideband tuning using an electro-optic modulator driven by an arbitrary waveform generator. A Fabry-Perot filter cavity selects a single sideband of the light source. The finesse (FSR/??FWHM) of the filter cavity may be chosen to enable rapid frequency switching at rates up to 5 MHz over a frequency range of 40 GHz (1.3 cm?1). The bandwidth, speed and spectral purity are high enough for spectroscopic applications where rapid and discrete frequency scans are needed. Significant signal-to-noise advantages may be realized using the rapid and broadband scanning features of this system in many areas of spectroscopy, e.g., process monitoring and control, reaction dynamics, and remote sensing (e.g., greenhouse gas monitoring, biological/chemical agent screening).

Abstract: This invention provides a novel methods and devices for measurement of particle concentration or changes in particle concentration over a wide linear range. The invention comprises one or more radiation sources and one or more detectors contained in a housing which is interfaced to a medium containing particulate matter. The one or more radiation sources are directed into the medium, scattered or transmitted by the particulate matter, and then some portion of the radiation is detected by the one or more detectors. Methods for confining the measurement to a specific volume within the medium are described. Algorithms are provided for combining the signals generated by multiple source-detector pairs in a manner that results in a wide linear range of response to changes in particle concentration. In one embodiment the sensor provides non-invasive measurements of biomass in a bioreactor. In another embodiment an immersible probe design is described, which may be suited for one-time use.

Abstract: The present invention provides synchronization and control between the wavelength of a multi-wavelength illuminator and the image frames acquired by a video camera. In accordance with the present invention, the trailing edge of a camera expose-signal triggers a pre-loaded digital value to be output from a FIFO buffer. The digital value selects a particular illumination wavelength either directly or through a voltage from a digital to analog converter. The FIFO may be periodically refilled, or it may be a circular register.

Abstract: The invention concerns a measurement system and method for optical spectroscopic measurement of samples. The system comprises an illumination source for forming a primary light beam, a first tunable monochromator for spectrally filtering the primary light beam, a sample-receiving zone to which the spectrally filtered primary beam is directed for producing a secondary light beam affected by a sample in the sample receiving zone, and a second tunable monochromator for spectrally filtering the secondary light beam, and a detector for measuring the intensity of the spectrally filtered secondary beam. In particular, the system is adapted to scan a predefined wavelength range using one of the monochromators and to tune the other monochromator sequentially to one of at least two predefined separate wavelengths in order to eliminate the effect of undesired diffraction orders of the second monochromator on the measurement.

Abstract: Methods and devices are disclosed which apply an excitation-emission matrix (EEM) to a heterogeneous, two-dimensional sample, allowing a considerably larger number of emitting, e.g. fluorescent, labels to be used simultaneously. This may be accomplished by employing a spectroscopic method of excitation-emission matrices which allows discrimination of species with similar emission spectra, and also allows positive identification of energy transfer between emitting species. The methods and devices may employ a novel excitation-light scanning technique which allows imaging of the emission from the heterogeneous sample both in two spatial dimensions (length and width) and in two spectral dimensions (excitation and emission wavelength). This light scanning technique maximizes the throughput of excitation light, increasing the sensitivity and hence the reading speed of the instrument.

Abstract: Various embodiments of a light filter are disclosed.

Abstract: A measuring device for measuring the height of a workpiece held on a chuck table provided in a processing machine. The measuring device includes a white light source for emitting white light, an acousto-optic deflecting unit for separating the white light emitted from the white light source to produce a flux of diffracted light and for swinging the flux of the diffracted light over a predetermined angular range by applying a voltage, a pinhole mask for passing light having a part of the wavelengths of the diffracted light produced by the acousto-optic deflecting unit, and a chromatic aberration lens for focusing the light passed through the pinhole mask and for applying the focused light to the workpiece held on the chuck table.

Abstract: A polarizing monochromator comprising a uniaxial birefringent crystal prism, the prism has the geometry of a triangular block having a triangular base, a face including a side of the hypotenuse is an input-output face, where light enters and exits, and a face including the longer side of the right angle is a reflection face, the optic axis of the prism is perpendicular to the base of the prism, the angle of the input-output face of the prism with respect to light coming from a collimator optical system is determined in such a manner that ordinary light and extraordinary light exit from the input-output face of the prism in opposite directions with respect to an optical axis connecting the collimator optical system and the prism, and a light-collecting optical system is disposed to collect either extraordinary light or ordinary light exiting from the input-output face of the prism.

Abstract: A light scanning type confocal microscope includes a light source unit that projects an excitation light beam, a scanning optical system that scans the excitation light beam, an objective lens that applies the excitation light beam to a sample, a separation optical element that separates the excitation light and detection light generated by the sample, a confocal detection unit that obtains a confocal effect, and a spectral detection device that spectrally detects the detection light. The spectral detection device has a spectroscopic element that spectrally separates the detection light, a light extracting unit that extracts light in a wavelength band from the light spectrally separated by the spectroscopic element, a detector that detects the light extracted by the light extracting unit, and a wavelength band shifting unit that shifts a wavelength band of light to be extracted by the light extracting unit.

Abstract: A system and a method for setting a fluorescence spectrum measurement system for microscopy is disclosed. Using illuminating light (3) from at least one laser that emits light of one wavelength, a continuous wavelength region is generated. Dyes are stored, with the pertinent excitation and emission spectra, in a database of a computer system (23). For each dye present in the specimen (15), a band of the illuminating light (3) and a band of the detected light (17) are calculated, the excitation and emission spectra read out from the database being employed. Setting of the calculated band in the illuminating light and in the detected light is performed on the basis of the calculation. Lastly, data acquisition is accomplished with the spectral microscope (100).

Abstract: An optical measurement device capable of improving optical spectrum measurement accuracy without the need to structurally decrease a slit width. A diffraction grating for dispersing measurement light into respective different wavelengths is rotated in a given direction to produce diffracted light of selected wavelengths. A focusing lens converges the diffracted light to produce a converged beam. A slit control section varies the slit width at a constant scan speed to open or close the slit, thereby varying the passing bandwidth for the converged beam. A light receiving/measuring section receives the light passed through the slit, obtains a level function indicative of the power level of the received light that varies with change in optical frequency, and differentiates the level function by the scan speed to reproduce the spectrum profile of the measurement light.

Abstract: An optical slit comprises two blades 40,42 which define a slit between them, each blade being independently movable. This enables both the slit position and the slit width to be adjusted. The slit may be aligned with the center of a light beam by aiming the light beam at a detector, traversing at least one edge of the slit across the beam path, measuring the intensity of transmitted light at the detector for each position of the slit, and feeding back a signal which adjusts the slit position for maximum light throughput. The width on the optical slit may be selected by placing the slit in the path of the light beam and measuring the light transmitted at the detector, calculating the percentage of light transmitted for that slit width and feeding back a signal which adjusts slit width to obtain the desired amount of light throughput.

Abstract: This invention refers to an imaging method and apparatus capable of performing non-destructive, in situ analysis of art-objects. The invention relays on the comparison of diffuse reflectance and/or fluorescence spectra (intensity vs. wavelength), of painting material models of known composition, with the intensities emitted and captured at the same wavelengths and for any spatial point of the art-object of unknown composition. This composition, performed for any spatial point of the area of interest, improves notably the diagnostic information and enables the analysis of heterogeneous art-objects.

Abstract: Disclosed are spectrophotometer systems and methodology for obtaining data of improved precision therefrom, including replacement of data determined to be suspect based on comparison of multiple baselines.

Abstract: A variable slit width device for a spectroscope which can be used in a narrow space, be widely variable, and be set in slit width with high accuracy. The variable slit width device includes a pair of freely rotatable rotary parts for pressing inclined guide parts of a pair of slit holders, pressing parts for supporting the pair of rotary parts, and linear guides having guide parts formed at the lower surfaces thereof and extending horizontally in a direction crossing with guide rails at right angles. The pressing parts are fixed to the linear guides, the guide rails are fitted to the guide parts of the linear guides, feed nuts are fixed to the pressing parts, feed screws are engaged with the feed nuts. Bearings are provided for rotatably supporting the feed screws, preload springs for preloading the feed nuts and the feed screws, a slit driving part for rotatably driving the feed screws, and a housing part for fixing thereto the guide rails, the bearings and the motor.

Abstract: Plane diffraction grating 13 is formed of a material having an appropriate linear expansion coefficient and a variation in the wavelength of the reflected light from concave mirror 14 on account of thermal expansion or shrinkage of members other than plane diffraction grating 13 is cancelled out or reduced by a variation in the wavelength of the reflected light from concave mirror 14 on account of thermal expansion or shrinkage of plane diffraction grating 13. The same principle is used to deal with the effect on the wavelength of the diffracted light that may be caused by changes in the layout of individual members on account of thermal expansion or shrinkage of substrate 10a that fix them.

Abstract: An optical spectrum analyzer 100 and a wavelength variable light source 101 have each a sweep synchronization start function. A correction function of the rotation speed of a motor 106 for varying the angle of a diffraction grating in a spectroscope 104 so that extracted wavelength and output signal light wavelength match over a setup sweep wavelength range is found from the output signal light wavelength characteristic relative to the rotation angle of a spectral element 119 and the extracted wavelength of the spectroscope 104, and the rotation angle of motor 106 for driving the spectroscope 104 is varied for each setup wavelength in accordance with the correction function, then sweep is performed.

Abstract: An embedded data acquisition and control system for a precision instruments, such as a non-invasive glucose prediction instrument is disclosed. One feature of the invention provides synchronization of stepper motor position and analog-to-digital converters. An embedded controller is provided that controls the stepper motor driver directly to minimize the wavelength shift error due to the asynchronous condition. The controller synchronizes the event of reading the A/D converters with each stepper motor position. Because the stepper motor controls the wavelength of the monochromator optical output, the net result is that each A/D conversion recorded by the embedded controller is precisely tracked to a specific wavelength. Another feature of the invention provides closed loop motor position control for enhanced system performance. In the closed loop system, a position encoder is coupled to the stepper motor shaft.

Abstract: A high resolution etalon-grating spectrometer. A preferred embodiment presents an extremely narrow slit function in the ultraviolet range and is very useful for measuring bandwidth of narrow band excimer lasers used for integrated circuit lithography. Light from the laser is focused into a diffuser and the diffused light exiting the diffuser illuminates an etalon. A portion of its light exiting the etalon is collected and directed into a slit positioned at a fringe pattern of the etalon. Light passing through the slit is collimated and the collimated light illuminates a grating positioned in an approximately Littrow configuration which disburses the light according to wavelength. A portion of the dispursed light representing the wavelength corresponding to the selected etalon fringe is passed through a second slit and monitored by a light detector. When the etalon and the grating are tuned to the same precise wavelength a slit function is defined which is extremely narrow such as about 0.

Abstract: An apparatus and method for producing a spectrally variable radiation source and systems including same is disclosed. An embodiment of a spectrally variable radiation source is disclosed including a broadband radiation source, a collimating element, a dispersive element, an imaging element, an output aperture and an optional output collimating element. An embodiment of a spectrally encoded infrared chromatograph incorporating the inventive spatially variable radiation source is disclosed. An arbitrary spectrum projector for simulating emission or absorption spectra for chemical and biological agents, as well as projecting calibration and test spectra for characterizing sensors is also disclosed.

Abstract: In order to start sweeping an optical spectrum analyzer 1 and a wavelength tunable light source 14 on the same timing, a motor 6 for driving a spectroscope 4 in the optical spectrum analyzer 1 is controlled. To this end, a drive circuit 7 outputs a control signal to determine the timing where the motor 6 starts to rotate. A wavelength control circuit 19 in the wavelength tunable light source 14 controls the sweep of the wavelength of single-mode oscillation from a light source unit 20 and starts sweeping the light source unit 20 in response to a signal externally supplied to control the timing of sweep start. As a result, the sweep of the wavelength being measured with the optical spectrum analyzer 1 and that of the wavelength of single-mode oscillation from the wavelength tunable light source 14 are started on the same timing and high-speed sweep is achieved.

Abstract: The invention concerns a device for adjusting angular play on a predetermined angular range of an optical element mobile in rotation relative to a frame. Said device comprises a contact piece (3), integral with the optical element, and an elastic steady arm (4). The steady arm has a first end (41) fixed to the frame and a second end (42) co-operating with the contact piece when the mobile element is oriented in the predetermined angular range, at least when the mobile element enters said angular range in the rotational direction (S1), such that the steady arm exerts on the mobile element a counter-torque. Said second end does not co-operate with the contact piece when the mobile element is oriented outside the angular range.

Abstract: There is provided variable slit width device for a spectroscope which can be used in a narrow space, be widely variable, and be set in slit width with high accuracy. The variable slit width device comprises a pair of freely rotatable rotary parts for pressing inclined guide parts of a pair of slit holders, pressing parts for supporting the pair of rotary parts, linear guides having guide parts formed at the lower surfaces thereof and extending horizontally in a direction crossing with the guide rails at right angles, and pressing parts being fixed to the linear guides, guide rails fitted to the guide parts of the linear guides, feed nuts fixed to the pressing parts, feed screws screwed with the feed nuts, bearings for rotatably supporting the feed screws, preload springs for preloading the feed nuts and the feed screws, a slit driving part for rotatably driving the feed screws, and a housing part for fixing thereto the guide rails, the bearings and the motor.

Abstract: An SNR calculation method having the steps of measuring the wavelength characteristic of a dynamic range in an optical spectrum measurement apparatus for each wavelength in a multiplexed wavelength range and storing the wavelength characteristic in a storage unit, measuring the signal level and the noise level of a measured optical signal wavelength, reading the noise level of the wavelength of the measured optical signal produced by each of other optical signal wavelengths multiplexed on the measured optical signal wavelength from the storage unit, subtracting the noise level read from the storage unit from the noise level of the measured optical signal wave length to provide the corrected noise level, and calculating the SNR of the measured optical signal from the measured optical signal level and the corrected noise level.

Abstract: In a monochromator including a light dispersing element rotatable about an axis, a linear motor for rotating the light dispersing element around the axis, an encoder for generating a signal representing a rotational position of the light dispersing element, and a linear motor controller for detecting the rotational position of the light dispersing element based on the signal generated by the encoder, the inventive monochromator is characterized in that the signal generated by the encoder has a waveform including no flat portion. That is, the strength of the signal must change if the rotational position of the light dispersing element changes even slightly. Using a linear motor as a driving unit for the light dispersing element, the monochromator of the present invention can rotate the light dispersing element constantly with a stable speed even at high speed.

Abstract: An imaging spectrometer provides a three-dimensional (two (2) spatial and one (1) spectral) image cube of a target. In this apparatus, a diffractive optical element (DOE) performs the imaging and provides the dispersion necessary to separate a multi-spectral target into separate spectral images that are detected by a photodetector array. A lens (or set of lenses) relays the image formed by the DOE to the photodetector array. This lens allows the DOE and photodetector array to be mounted with a fixed separation and the spectral images to have a constant magnification. The lens is stepped or scanned along the optical axis, and each position of the lens corresponds to a particular wavelength being imaged onto the photodetector array. At each position of the relay lens the photodetector array records a spectral image by a process called diffractive spectral sectioning.

Abstract: The object of the present invention it to provide an optical spectrum calculation method that can find an optical spectrum by an arbitrarily determined wavelength bandwidth even in a spectrometer in which the width of the emission slit cannot be arbitrarily changed.In order to attain this objective, a wavelength bandwidth memory unit 40 is provided, and in this wavelength bandwidth memory unit 40, the characteristics of the transiting wavelength bandwidth for the measured wavelength of spectrometer 5' are recorded. CPU 34 finds the wavelength bandwidth for each measurement point based on the recorded wavelength bandwidth.

Abstract: A spectrophotometer employs an array of optical elements to focus light from at least one, but preferably two light sources onto a fiber optic beam splitter that provides a pickup for a selected bandwidth of wavelengths of light in the spectral pattern. The spectral pattern can include wavelengths in the visible, near infrared and ultraviolet spectrum. To create the spectral pattern, two reflecting prisms having spherical surfaces are used, and the optical elements are arranged so that the two spectral bands from each prism are longitudinally aligned to create the spectral pattern. The prisms are on a motor driven pivot mount so that the spectral pattern may be swept across the pickup. The optical elements and the pickup are sized so that the selected bandwidth is less than twenty nanometers over the spectral pattern. The pickup is formed by a single row of the ends of fiber optic strands which are then collimated into two bundles to transmit a test component and a reference component of light.

Abstract: A system for translating applied linear motion into a slit width present between facing edges of two "Knife-blade" elements. In its preferred embodiment, two slide assemblies are firmly affixed to a frame such that loci of motion of slide elements thereof form an acute angle therebetween. Lower ends of each slide element, as viewed in vertically oriented frontal elevation, allow horizontal motion therebetween when said slide element lower ends are caused to simultaneously move vertically. An alternative embodiment provides that the slide elements be oriented such that said loci of motion of said slide elements are, for instance, horizontally directed. In its preferred embodiment the simultaneous motion of the slide elements is effected by a motor, preferably a precisely controlled computer driven stepper motor, which motor causes a threaded shaft therein to move vertically as a result of screw thread translation of motor imparted rotational motion to said threaded shaft.

Abstract: A scanning monochromator system which uses a directly coupled stepper motor to drive a spectral-dispersion element. The spectral-dispersion element is directly coupled to the output shaft of the motor. The movement of the motor is controlled with an electronic circuit that controls the motor winding current. The circuit includes a power driven section, a pulse-width modulator section and a computer section. The power driven section switches electrical current through the motor windings and can produce a variable pulse-width ranging from 0 to 100 percent modulation. The pulse-width modulator section accepts values from the computer section and converts these values into variable pulse-width signals for use by the power driver section. The computer section supplies values to the pulse-width modulator section based upon requirements for the motor movement and position. The required motor position is determined by the type of spectral-dispersion element and the desired wavelength selection of the monochromator.

Abstract: A differential spectrometry system detects very narrow-band spectral features, while providing much higher optical transmittance and signal-to-noise ratios than prior optical-filter-based spectrometer systems. A plurality of light detectors (10a, 10b) detect light that falls within respective wide wavebands. The wide wavebands have overlapping and non-overlapping portions, one of which is the desired narrow waveband. The detector outputs are operated upon to produce an output signal (22) which includes substantially only the desired narrow waveband. In the preferred embodiment, the light detectors (10a, 10b) are implemented with a pair of optical detectors (30a, 30b) and respective optical interference filters (24a, 24b). The filters have substantially identical cut-off wavelengths (.lambda..sub.2) and cut-on wavelengths that are shifted by .DELTA..lambda. with respect to each other (.lambda..sub.1 and (.lambda..sub.1 +.DELTA..lambda.), respectively).

Abstract: An Echelle polychromator 50 has disposed upstream thereof a pre-monochromator 14 comprising a prism 20. The linear dispersion of the pre-monochromator 14 is variable by varying the angular dispersion of the prism 20. A particular spectral position and the close vicinity thereof are analyzed by an Echelle grating 54 with high resolution. Care must be taken that, on the one hand, the detector array 66 of the Echelle polychromator 50 is fully exploited in response to the central wavelength respectively observed and that, on the other hand, interfering orders are kept away from the Echelle polychromator 50. The linear dispersion of the pre-monochromator is variable for this purpose.

Abstract: A random access monochromator is disclosed. This device has no mechanical parts and eliminates the need to scan sequentially the wavelengths of light contained in a light spectrum to select a desired wavelength or wavelengths from the spectrum. The device has high speed switching means, permits one to select multiple wavelengths and bandwidths at the same time, and has the ability to correct for non-linearity in prisms caused by their nonlinear or second order dispersion of light.

Abstract: In quantitative analysis of a sample by using the spectrum thereof by means of a spectrophotometer, at a specific wavelength or in a specific wavelength range where a quantitative determination is to be conducted, wavelength scanning is temporarily stopped or its speed is slowed down so as to obtain spectral data from the sample, so that the accuracy of the data obtained is improved. In the wavelength range where no quantitative determination is to be conducted, the scanning operation is conducted at an ordinary relatively fast speed, so that the total time required for the analysis will not be lengthened.

Abstract: Iterative compensation of drift of peak positions of spectral lines is effected in a spectral monochromator including a grating, a detector of spectral fractions of a spectral band, a stepper motor for varying relative orientation of the grating and the detector, and a computer. Computer-defined spectral windows each encopasses a spectral band and has an initial spectral center. Each window is scanned to determine a peak spectral position. Calculation is made for determining a spectral position error of the peak position from the initial center for each corresponding window. A functional average of the offsets for the peaks is calculated as a linear function of window position, and a revised spectral center for each window is calculated as being equal to the initial center plus the functional average for the window position determined from the linear function. Each window is shifted correspondingly.

Abstract: An optical component comprises a thin film of an electrically controllable birefringent material confined between substantially planar surfaces. A respective electrode structure is provided on each of the surfaces, each electrode structure being patterned such that an electric field applied across the film by means of electrode structures, when a voltage is applied therebetween, causes modulation of the refractive index of the material such that the wavefront of electromagnetic radiation incident of the component and transmitted through the thin film is divided into Fresnel zones.

Abstract: An adjustable Echelle spectrometer arrangement which can be used in single- and multi-element analysis by the emission or absorption of optical radiation. To compensate all the manufacturing and setup errors, the only arrangements present are those to change the height of the entry slit arrangement above the base plate and to rotate the dispersion prism about a first axis, approximately parallel to its roof edge, and about a second axis, that is vertical thereto. This compensates for the effect of errors associated with component and setup parameters which results from greater tolerances, without impairing mechanical and thermal stability and imaging quality.

Abstract: A photoelastic effect measuring device comprising a single white light source, a prism dispersing light emitted by said white light source and a variable slit device, which selects an arbitrary spectrum of light thus dispersed is disclosed, in which for a photoelastic effect measurement using white light, the slit width is opened totally so that all the light spectrum pass therethrough so as to pass through a sample to be measured and for a photoelastic effect measurement using a specified monochromatic light beam, the slit width is controlled so as to have a predetermined opening so that only a specified light spectrum can pass therethrough so as to pass through a sample to be measured.

Abstract: The invention relates to a selective detector arrangement for the detecting of approximately point-like collected light in a predetermined wavelength region and angle of the field of vision, with an optical collector system which is made from a material passing the light at a predetermined wavelength range and with a light sensitive sensor element.

Abstract: An image monochromator is arranged to receive light at an input thereof simultaneously from an entire object field to be viewed and to produce and transmit a viewable image of the entire object field simultaneously through an output thereof at a selected wavelength band. The monochromator has inner and outer optical systems, the inner system comprising an input slit which is projected on an output slit through imaging means such as lenses or mirrors, via dispersive means such as a diffraction grating or prism operable to transmit light at a tunable narrow wavelength band.

Abstract: The invention relates to an optical system for spectral analysis devices particularly for use in atomic emission spectroscopy in which the aberrations, astigmatis and coma are compensated separately, comprising two concave spherical reflectors adjacently arranged and having their vertices equidistantly located relative to a center of a dispersing member. The latter has a dispersion plane at right angles to the dispersing structure of the dispersing member and to its surface, the vertices are located in said dispersion plane. The center beams originating from an excitation light source are reflected at the reflectors in reflection planes which are at right angles to the dispersion plane. The light entrance of the optical system comprises two slits the images of which coincide in a focal plane. The center of the focal plane and the light entrance have a same distance to the dispersion plane and are located on different sides of the latter.

Abstract: Output data from a spectrophotometer may be presented as a series of data values representative of the intensity amplitude of pass bands having equal bandwidths (resolution) and spaced at wavelength intervals equal to the bandwidth. For some purposes it is desirable to increase the bandwidth of said data, and this invention discloses method and apparatus for converting such data to equivalent data having a selected greater bandwidth.

Abstract: A wavelength driving device for use in monochromators which comprises an optical element for dispersing light into different wavelengths, means for supporting the optical element for rotation about a first axis, a stepping motor, a first toothed pulley of a relatively small diameter connected to the output shaft of the stepping motor for simultaneous stepwise rotation therewith, a first gear of a relatively large diameter fixed to the supporting means for simultaneous rotation about the first axis, a second gear of a relatively small diameter mounted for rotation about a second axis and meshing with the first gear, a second toothed pulley of a relatively large diameter fixed to the second gear for simultaneous rotation about the second axis, a toothed belt connecting the first and second toothed pulleys, and circuit means for controlling the rotation of the stepping motor.

Abstract: A method and apparatus for controlling the spectral components of a light beam are described. The apparatus comprises means (3-7) for generating a collimated light beam; means (9) for dispersing the collimated beam; a mask (1) including an aperture (2) the size of which is such that a portion of the dispersed beam passes through the aperture in use; and movement means (not shown) for causing relative transverse movement between the light beam and the aperture. A memory (not shown) is provided for storing in use a profile of the relative transverse movement between the light beam and the aperture (2) required to obtain a desired spectral response in the transmitted light beam, the movement means being responsive to the stored profile to cause relative transverse movement in accordance with the predetermined profile.

Abstract: A holographic grating spectrophotometer for detecting ozone and sulphur dioxide in the atmosphere is described which provides automatic calibration and which provides automatic linearity correction for the photomultiplier tube. Automatic calibration is provided by using a computer to control a stepper motor to move the grating so that the photomultiplier tube receives maximum intensity at the calibration wavelength of 302.1 nm from a mercury source. Automatic linearity correction is obtained by cycling a wavelength selection mask across exit slits located in the focal plane of the device and firstly combines separately taken counts of two different wavelengths and comparing this sum with the sum of counts of these wavelengths taken simultaneously. The difference is used to calculate photomultiplier tube deadtime and improve accuracy of the results.