Abstract: A calibration assembly for a spectrometer is provided. The assembly includes a spectrometer having n detector elements, where each detector element is assigned a predetermined wavelength value. A first source emitting first radiation is used to calibrate the spectrometer. A device is placed in the path of the first radiation to split the first radiation into a first beam and a second beam. The assembly is configured so that one of the first and second beams travels a path-difference distance longer than the other of the first and second beams. An output signal is generated by the spectrometer when the first and second beams enter the spectrometer. The assembly includes a controller operable for processing the output signal and adapted to calculate correction factors for the respective predetermined wavelength values assigned to each detector element.

Abstract: There is provided a method for referencing and correcting the beating spectrum generated by the interference of the components of a frequency comb source. The proposed method allows monitoring of variations of a mapping between the source and the beating replica. This can then be used to compensate small variations of the source in Fourier transform spectroscopy or in any other interferometry application in order to overcome the accuracy and measurement time limitations of the prior art. Constraints on source stability are consequently reduced.

Abstract: Calibration of an arbitrary spectrometer can use a stable monolithic interferometer as a wavelength calibration standard. Light from a polychromatic light source is input to the monolithic interferometer where it undergoes interference based on the optical path difference (OPD) of the interferometer. The resulting wavelength-modulated output beam is analyzed by a reference spectrometer to generate reference data. The output beam from the interferometer can be provided to an arbitrary spectral instrument. Wavelength calibration of the arbitrary spectral instrument may then be performed based on a comparison of the spectral instrument output with the reference data. By appropriate choice of materials for the monolithic interferometer, a highly stable structure can be fabricated that has a wide field and/or is thermally compensated. Because the interferometer is stable, the one-time generated reference data can be used over an extended period of time without re-characterization.

Abstract: A method of comb-based spectroscopy with synchronous sampling for real-time averaging includes measuring the full complex response of a sample in a configuration analogous to a dispersive Fourier transform spectrometer, infrared time domain spectrometer, or a multiheterodyne laser spectrometer. An alternate configuration of a comb-based spectrometer for rapid, high resolution, high accuracy measurements of an arbitrary cw waveform.

Abstract: A system for measuring a phase-matching spectral phase curve by nonlinear spectral interferometry includes a broadband light source, a first beam splitter, a first nonlinear crystal, a second nonlinear crystal and a spectrometer. The first beam splitter splits the broadband light source into a first light and a second light. The first nonlinear crystal is used for converting the first light into a third light, wherein the third light has a reference phase spectrum. The second nonlinear crystal is used for converting the second light into a fourth light which encoded a phase-matching spectral phase of the second nonlinear to crystal. The spectrometer is used for providing an interferogram from an interference between the third light and the fourth light. Thus, by analyzing the interferogram, the phase-matching spectral phase curve of the second nonlinear crystal can be measured without knowing the spectral phase of the broadband light source.

Abstract: A device can be used for establishing gas concentrations in an examination volume. A radiation source is configured to generate an electromagnetic beam. A beam guiding apparatus is arranged downstream of the radiation source. The beam guiding apparatus is configured to set a plurality of variations of beam guidance of the beam entering the beam guiding apparatus in an observation plane in the examination volume. A spectrometer is arranged downstream of the beam guiding apparatus. The spectrometer is configured to carry out a spectral analysis of the beam leaving the beam guiding apparatus. An evaluation unit is configured to establish in the observation plane a 2D concentration distribution for one or more gases in the examination volume on the basis of the spectral analysis for different variations of beam guidance.

Abstract: The present invention relates to a system and methods for acquiring two-dimensional Fourier transform (2D FT) spectra. Overlap of a collinear pulse pair and probe induce a molecular response which is collected by spectral dispersion of the signal modulated probe beam. Simultaneous collection of the molecular response, pulse timing and characteristics permit real time phasing and rapid acquisition of spectra. Full spectra are acquired as a function of pulse pair timings and numerically transformed to achieve the full frequency-frequency spectrum. This method demonstrates the ability to acquire information on molecular dynamics, couplings and structure in a simple apparatus. Multi-dimensional methods can be used for diagnostic and analytical measurements in the biological, biomedical, and chemical fields.

Abstract: In a rough adjustment step before spectroscopic analysis, a moving mirror is moved (#1), the outputs of division elements when the interfering light of reflected light off the moving mirror and reflected light off a fixed mirror is received by a four-division sensor are totalized and variations in the contrast of the interfering light are detected (#12), and, based on the variations in the contrast, the amount of relative tilt of the two reflected light beams is detected (#13), and the initial tilt error is corrected (#14). In a fine adjustment step before the spectroscopic analysis, based on a phase difference between the outputs of the division elements when the interfering light is received by the four-division sensor, the relative tilt amount of and the tilt direction of the two reflected light beams are detected, and the initial tilt error is corrected.

Abstract: An interferometer (1) measures a measuring interference beam, while detecting the position of a moving mirror (16) on the basis of detection results obtained from a reference beam detector (25). In the interferometer, a reference beam source (21) is configured by including a light source (21a) composed of a semiconductor laser device. A reference optical system (20) has a collimating optical system (22) for a reference beam, said collimating optical system converting a laser beam outputted from the reference beam source (21) into a collimated beam, and the collimated beam is diagonally inputted to a fixed mirror (15).

Abstract: Multiple rays such as scattered lights and fluorescent lights emitted radially in a variety of directions from each bright point in a measurement area enter an objective lens, where the multiple rays are converted into a parallel beam. The parallel beam is reflected by both a reference mirror unit and an oblique mirror unit, and the reflected beams pass through an imaging lens to form an interference image on a light-receiving surface of a detection unit. The detection of the light intensity of the interference image on the light-receiving surface enables an acquisition of the interferogram (the waveform of the change of imaging intensity) in which the light intensity continuously changes. By Fourier-converting the interferogram, spectral characteristics can be obtained which show the relative intensities for each wavelength of the lights emitted from one bright point of an object to be measured.

Abstract: An information acquiring apparatus includes a light source portion for generating pulse-shaped pump light, and first and second probe light in synchronization with each other. A generating portion generates terahertz pulses when irradiated with the pump light. A detecting portion detects pulses of terahertz radiation from the object. A first delay portion adjusts an optical path difference between optical paths of the pump light and the first probe light reaching the detecting portion, so that the detecting portion detects a field intensity of a fixed point on the time domain waveform of the terahertz pulse from the object, following the fixed point. A second delay portion adjusts an optical path difference between the optical path of the pump light and the second probe light reaching the detecting portion by a sum of an additional optical path adjustment amount and the optical path difference, so that the detecting portion obtains the time domain waveform.

Abstract: A spectrometric instrument comprising: a scanning interferometer having a beamsplitter for dividing incident optical radiation into a reflected beam, following a reflected beam path and a transmitted beam following a transmitted beam path; a monochromatic optical radiation source for launching a reference beam into the interferometer along a first propagation path to be initially incident on a first face of the beamsplitter; an observation optical radiation source for launching a divergent observation beam into the interferometer along a second propagation path to be initially incident on the first face of beamsplitter and overlap the reference beam at the first face; wherein the radiation sources cooperate to generate a first angle between the directions of propagation of the two beams along respective first and second propagation paths when initially and simultaneously incident at the first face which is larger than a divergence half-angle of the observation beam 64.

Abstract: An optical low-coherence reflectometry with spectral reception for obtaining images without coherent noise caused by self-interference of the radiation scattered from the studied object and by spurious reflections in the optical path of the system is disclosed. Two or more consecutive measurements of the interference spectrum are made. During at least one measurement of the interference spectrum by means of the interference control unit the phase between the interfering parts of the radiation is modulated by a certain law during exposure, which results in averaging and zeroing of the cross-correlation (useful) component of the registered spectrum, and during at least one additional measurement of the interference spectrum, the phase between the interfering parts of the radiation is not modulated during exposure. The phase between the interfering parts of the radiation may be set to be different in additional measurements of the interference spectrum.

Abstract: A heterodyne photomixer spectrometer comprises a receiver photomixer that is driven at a different frequency than the source photomixer, thereby maintaining the coherent nature of the detection, eliminating etalon effects, and providing not only the amplitude but also the phase of the received signal. The heterodyne technique can be applied where the source and receiver elements are components of a waveguide thereby forming an on-chip heterodyne spectrometer.

Abstract: There is provided a method for referencing and correcting the beating spectrum generated by the interference of the components of a frequency comb source. The proposed method allows monitoring of variations of a mapping between the source and the beating replica. This can then be used to compensate small variations of the source in Fourier transform spectroscopy or in any other interferometry application in order to overcome the accuracy and measurement time limitations of the prior art. Constraints on source stability are consequently reduced.

Abstract: A spectral interferometry apparatus and method is provided to supply unambiguous profiles (A-scans free of mirror terms) of the reflectivity versus optical path difference and make difference between the positive and negative optical path difference or provide output in a selected interval of optical path differences. The apparatus comprises object optics that transfer a beam from an optical source to a target object (55) to produce an object beam and reference optics that produce a reference beam. Displacing means (57) are provided to produce a gap (g) between the object beam (41?) and the reference beam (42?). Optical spectrum dispersing means (7) such as a grating or a prism receive the two relatively displaced beams, and disperse their spectral content onto a reading element such as a CCD.

Abstract: A spectrum detecting device including a laser apparatus, an optical splitting apparatus, an optical gate, a first polarizer, a second polarizer, and an optical analysis apparatus is provided. The optical splitting apparatus splits the laser beam providing from the laser apparatus into a first and a second light beam, and the second light beam is transmitted to a sample to produce a spectral signal. The optical gate activated by the first light beam is disposed between the optical analysis apparatus and the sample. The first polarizer is disposed between the sample and the optical gate, and the second polarizer is disposed between the optical gate and the optical analysis apparatus. The spectral signal passes through the first polarizer, the optical gate, and the second polarizer to be transmitted and received to the optical analysis apparatus when the optical gate is activated and turned on in a predetermined time period.

Abstract: A microstructured sensor for detecting IR radiation includes: one measuring channel having a measuring diaphragm, on which a first sensitive detector surface is implemented for the absorption of a first IR radiation; and one reference channel having a reference diaphragm, on which a second sensitive detector surface is implemented for the absorption of a second IR radiation. A measuring structure, e.g., a thermopile measuring structure as a series circuit made of thermocouple pairs, is implemented between the measuring diaphragm and the reference diaphragm for measuring a temperature differential between the measuring diaphragm and the reference diaphragm. First and second thermal contacts lie alternately on the two diaphragms.

Abstract: A method for monitoring of siloxane compounds in a biogas includes the step of generating a first absorption spectrum based on a ratio of a first spectral measurement and a second spectral measurement. The first spectral measurement is from a non-absorptive gas having substantially no infrared absorptions in a specified wavelength range of interest and the second spectral measurement is from a sample gas comprising the biogas. The method also includes the step of calculating a concentration of at least one siloxane compound in the biogas using a second absorption spectrum based on, at least, a first individual absorption spectrum for a known concentration of the at least one siloxane compound.

Abstract: An optical interference apparatus of detecting an object is provided. The optical interference apparatus includes a light source capable of emitting a light beam, an optical coupler, a reflector, a first lens set and a light sensing unit. The optical coupler is capable of dividing the light beam into a measuring sub-light beam and a reference sub-light beam. The reflector reflects the reference sub-light beam. The first lens set includes a first lens. The measuring sub-light beam is transmitted to the object. The object reflects or scatters a part of the measuring sub-light beam back to the first lens. The first lens is capable of extending a depth of field of the first lens set. The light sensing unit is adapted to detect an interference signal formed by the reference sub-light beam and the measuring sub-light beam.

Abstract: Current apparatuses and methods for analysis of spectroscopic optical coherence tomography (SOCT) signals suffer from an inherent tradeoff between time (depth) and frequency (wavelength) resolution. In one non-limiting embodiment, multiple or dual window (DW) apparatuses and methods for reconstructing time-frequency distributions (TFDs) that applies two windows that independently determine the optical and temporal resolution is provided. For example, optical resolution may relate to scattering information about a sample, and temporal resolution may be related to absorption or depth related information. The effectiveness of the apparatuses and methods is demonstrated in simulations and in processing of measured OCT signals that contain fields which vary in time and frequency. The DW technique may yield TFDs that maintain high spectral and temporal resolution and are free from the artifacts and limitations commonly observed with other processing methods.

Abstract: A quasi-translator for economically producing pure, smooth translational motion with broad arcuate or error-free motion regardless of orientation, which is useful in numerous interferometer applications including spectroscopy, a Fourier modulator and a Fourier spectrometer are provided. The quasi-translator utilizes a support, an arm including a driving magnet on a first end and a driven element on a second end, an axis for rotation of the arm, a bearing system that controls the rotation of the arm about the axis, a drive coil and a drive amplifier to drive the arm in the arcuate motion. The quasi-translator may be employed in a Fourier modulator to change the optical path difference of the interferometer/quasi-translator at a substantially constant rate of change. The quasi-translator and/or Fourier modulator may be used in a Fourier spectrometer to create an optical spectrum from a light beam and/or electrical signal created from the light beam.

Abstract: The interference optical system includes a light source, a collimator, a light-receiving element, a tunable filter, and a calculation apparatus. The collimator emits measuring light from the light source to a first main surface of the object, and receives reflected light from the first main surface and a second main surface. The light-receiving element acquires an intensity of light from the collimator. The tunable filter sweeps a wavelength of the light incident to the light-receiving element. The calculation apparatus measures an interference intensity distribution that has wavelength dependence and is an intensity distribution of the reflected light from the first main surface and the second main surface, and measures the thickness or the temperature of the object based on a waveform obtained by Fourier transforming the interference intensity distribution.

Abstract: Every depth of the measurement object measures energy structural information, refractive index, transmittance, reflectance other than property information of (as for the resolution several microns), e.g., space information at the same time. A spectrum measurement device receives a reference wave propagating in a reference path and a measurement wave propagating in a measurement path having a start point same as a start point of the reference path, and derives a spectrum of the measurement wave. The space information of the measuring object, energy structural information, refractive index, transmittance, a reflective index using spectrum measurement device are derived.

Abstract: The reported invention belongs to spectral interference devices and can be used for spectral research in various fields of technology. The objective of the present invention is to improve the optical characteristics of the spectrometer in which reduced loss of light from the radiation object on aberration is attained with a minimum number of optical elements produced at lower costs. The objective is achieved by the fact that the static Fourier spectrometer contains an input collimator optically coupled with the interferometric unit consisting of a beam splitter and at least two mirrors installed with the ability to create an interference image localized in the plane of the mirrors, and an image recording device optically coupled with the interferometric unit by means of the projective system with the ability to project the figure of the indicated interference image on the image recording device.

Abstract: A transform spectrometer measurement apparatus and method for a planar waveguide circuit (PLC). The spectrometer typically includes an input optical signal waveguide carrying an input optical signal; a plurality of couplers, each connected to the input optical signal waveguide, and each including a coupler output for carrying a coupled optical signal related to the input optical signal; and an array of interleaved, waveguide Mach-Zehnder interferometers (MZI), each having at least one input MZI waveguide, each MZI input waveguide receiving a coupled optical signal from a respective coupler output. A phase shifting circuit is applied to at least one arm of the MZIs to induce an active phase shift on the arm to thereby measure phase error in the MZIs. Light output from the MZIs is measured under intrinsic phase error conditions and after an active phase shift by the phase shifting circuit.

Abstract: A detection apparatus and an imaging apparatus are capable of accurately conducting non-destructive observation of a target by using an incoherent electromagnetic wave. The detection apparatus has a generating section, a first coupler section, a delaying section, a second coupler section and a signal processing section. The generating section 101 includes a coherent electromagnetic wave source 102 and a diffusing section 103 for generating a pseudoincoherent electromagnetic wave by changing a propagation state of the coherent electromagnetic wave in accordance with a code pattern. The incoherent electromagnetic wave is split into first and second waves and the first wave is affected by the target of observation while the second wave is delayed by the delaying section. The first and second waves are then coupled to produce a coupled wave having a correlation signal of them and the signal is utilized to acquire information on the inside of the target of observation.

Abstract: An optical assembly for use in coherent two- or more-dimensional optical spectroscopy includes a beam splitter that splits a base light pulse into first, second, third and fourth light pulse and a delay element that varies the arrival times of the first to fourth light pulses at a sample location with respect to each other. The beam splitter includes a cross-grating a first reflector arranged to receive the first to fourth light pulses emerging from the cross-grating and to reflect the same in parallel to each other, a second reflector arranged to receive the first to fourth light pulses from the delay element and to focus the same at the sample location, wherein the delay element is arranged between first and second reflectors. Also shown is an apparatus including such optical assembly and a method for carrying out two- or more-dimensional optical spectroscopy using the assembly.

Abstract: In the field of Fourier transform interferometry and in particular a device and a method for improving the precision of such a device for remotely analysing a gaseous compound, a Fourier transform interferometer includes: at least one movable retroreflector; a metrology subsystem using at least three laser beams; and a metrology unit generating, for each sounding point represented by a pixel on the capture matrix imaging a gaseous compound, a metrology signal incorporating the displacements in space of the movable element(s).

Abstract: An apparatus for interrogating wavelength-specific devices has a broadband optical source to illuminate an interferometer which provides a low coherence temporal interferogram. At least one array of wavelength-specific devices, such as fiber Bragg gratings connected in series with one another, receives the interferogram, so that each device interacts with a limited range of wavelength bandwidth relative to the bandwidth of the broadband optical source. Instead of illuminating an interferometer with the output of an array of devices which have each interacted with a broadband light source at their own characteristic wavelengths, therefore, an interferometer is used to modulate the output from a broadband source to produce a low coherence interferogram. The array of devices then extracts or filters a higher coherence interferogram from this low coherence interferogram.

Abstract: The disclosure relates to a cold atom interferometry sensor that includes: a source of atoms; a dual-frequency laser capable of generating a first Raman dual-frequency laser beam; a reflector arranged so as to reflect the first Raman dual-frequency laser beam in order to generate a second Raman dual-frequency laser beam, the first laser beam and the second laser beam propagating in different directions in order to obtain atomic interference fringes from the emission of cold atoms obtained from the atom source; characterized in that the reflector is further arranged so as to enable multiple reflections of the first beam on surfaces of the reflector, so that the first beam and the multiple reflections thereof allow the capture of atoms from the atom source in order to obtain the cold atoms.

Abstract: An optical coherence tomography (OCT) system comprising: a splitter configured to receive and split an optical source beam generating a reference beam and a sample beam, the sample beam directed at a sample and interacting with the sample to generate a return beam; a delay module configured to receive and introduce an optical delay in the reference beam, to generate a delayed reflected beam configured to interfere with the return beam to generate an interferogram; a spatial filter system capable of filtering randomly scattered light from at least one of the return beam or the interferogram; and a detector array to receive the interferogram for spatial and spectral analysis.

Abstract: An apparatus includes a transverse scanning optical system in the path of a first light beam traveling along a first optic axis; a wavefront correction system in the path of a second light beam traveling along a second optic axis, the wavefront correction system including a wavefront correction device having a spatial phase profile on its surface; a beam combiner that receives the first light beam and the second light beam and outputs an interference beam having a beat frequency equal to a difference frequency between the first light beam and second light beam; and a detection system placed relative to a random scattering medium, which is in the path of the interference beam. The detection system detects measurement light produced by the random scattering medium while the interference beam strikes the random scattering medium.

Abstract: A method is provided to calibrate a detection array used for acquiring an image of an interferogram at an instrument. A first interferogram and at least two shifted interferograms are elaborated at the instrument by creating a number of optical path differences, so at least three samples are on a sine wave portion for each optical path difference. A function coinciding with the sine wave portion is determined by interpolation. A calibration coefficient is determined from the function for each optical path difference.

Abstract: Provided is a small, highly accurate Fourier spectrometer which enables highly accurate detection of an optical path difference in an interferometer. An element for changing to a narrow band is provided to return reflected light to a second light source (4), and the wavelength of light emitted by the second light source is locked, whereby the position of a movable mirror (8) is measured highly accurately and an optical path length (1) and an optical path length (2) match highly accurately.

Abstract: An improved interferometer measurement system is presented. In a preferred embodiment, a chirped fiber Bragg grating is used as a reference surface in a Fizeau interferometer arrangement for optical coherence tomography imaging of the eye. The grating creates a virtual reference surface near the sample and allows for a relatively short reference arm while maintaining close to zero delay interference conditions.

Abstract: Methods and apparatus for selectively driving the vibrations of normal modes of a target molecule into coherence using stimulated Raman scattering. In concert, many vibrations produce a larger anti-Stokes signal than a single vibration. The same illumination does not drive other molecules to have coherent vibrations, so these molecules produce a weaker signal. Target and confounder molecules can be distinguished by pulses that drive many vibrations coherently, with applications in coherent Raman microspectroscopy.

Abstract: This invention relates generally to the systems and methods for standoff trace chemicals detection such as explosives residue and others, and particularly to optical devices and the methods of their use based on sensing of gases and residue materials. This sensing includes detection and measurement of optical absorption spectra and relative concentration of the chemical followed by the chemical identification based on these spectral data. The sensing is based on photothermal interferometry method improved by implementation of coherent optical detection. The coherent optical detection is performed by an integrated polarization-diversity coherent receiver with an electro-optic phase modulator for a local oscillator optical beam. The implementation of pulsed probe sensing and local oscillator optical beams in the coherent detection improves the device with better eye safety performance.

Abstract: A device (10) and methods for simultaneously measuring the thickness of individual wafer layers, the depth of etched features on a wafer, and the three-dimensional profile of a wafer. The structure of the device (10) is comprised of a source/receiver section (12) having a broadband source (14), a receiver (16) and a signal processing section (20). An interferometer (28) separates or combines measurement and reference light and has a measurement leg (30) and a reference leg (34), and a reference mirror (36). The device (10) analyzes a received spectrum which is comprised of a measurement of intensity versus wavelength. There are two measurement methods disclosed: the first method is utilized for taking a single measurement and the second method is utilized for multiple measurements.

Abstract: Various systems and methods for analysis of optical pulses are provided. In one embodiment, a method is provided including obtaining a plurality of traces produced by propagating an unknown pulse and a reference pulse along a pair of crossing trajectories through a spectrometer, where each trace is associated with a delay between the unknown pulse and the reference pulse. Each trace is spatially filtered to generate a plurality of spatially filtered electric field measurements, which are temporally filtered to generate a plurality of temporally filtered electric field measurements. The plurality of temporally filtered electric field measurements are concatenated based at least in part upon the delay associated with the corresponding trace to generate a concatenated wave form corresponding to the unknown pulse.

Abstract: A system for grading an agricultural product employing hyper-spectral imaging and analysis. The system includes at least one light source for providing a beam of light, an interferometer or a prism array for dispersing electromagnetic radiation emitted from said agricultural product into a corresponding spectral image, a light measuring device for detecting component wavelengths within the corresponding spectral image and a processor operable to compare the detected component wavelengths to a database of previously graded agricultural products to identify and select a grade for the agricultural product. A method for grading an agricultural product via hyper-spectral imaging and analysis is also provided.

Abstract: In cavity ring-down spectroscopy (CRDS), scattering into the backward mode of a traveling wave ring-down cavity can degrade conventional CRDS performance. We have found that this performance degradation can be alleviated by measuring the backward mode signal emitted from the ring-down cavity, and using this signal to improve the processing for extracting ring-down times from the measured data. For example, fitting an exponential to the sum of the intensities of the forward and backward signals often provides substantially better results for the ring-down time than fitting an exponential to the forward signal alone. Other possibilities include extracting cavity eigenmode signals from the forward and backward signals and performing separate exponential fits to the eigenmode signals.

Abstract: The device is a gas/vapor/aerosol/particulate sensor with a receiver/transmitter option. This optical MEMS device is designed to be a self-contained optical bench, integrating of an entire interferometer into a MOEMS ‘optical bench’ system-on-a-chip, and includes multiplexed optical path sensors. The sensing structures consist of laser sources, semiconductor photo detectors, refractive/reflective optical elements, and specialized optical transmission paths. Each individual laser source and photodiode is an optical path sensor with a particular ‘functionalization.’ These sensing arm functionalizations are sensitive to unique chemical signatures and as a result can recognize and report various chemical agents present in the ambient environment.

Abstract: Described are methods for multi-wavelength cavity ring-down spectroscopy; comprising simultaneously and continuously irradiating an optical cavity with light at two or more different wavelengths, each light being intensity-modulated at a different modulation frequency, detecting the light of two or more wavelengths after the light has travelled through the optical cavity; measuring an optical loss of each detected light; and determining a characteristic of the optical cavity from the optical loss of each detected light. Also described are apparatus and systems for multi-wavelength cavity ring-down spectroscopy.

Abstract: A four port scanning Michelson interferometer suppresses self-emission by using either a beamsplitter that is uncoated or a beamsplitter that has reflection enhancing dielectric coatings in the splitting and combining areas of the substrate on opposite sides of the substrate. Both beamsplitters are fabricated from infrared optical materials that have a predetermined absorptivity in a predetermined wavelength interval which is from 2 ?m (5000 cm?1) to 13 ?m (770 cm?1) in the infrared. The optical materials of the uncoated beamsplitter are selected from a group of materials made up of ZnSe, ZnS, CdS, CdTe, Silicon, Germanium or Diamond. The optical materials of the other beamsplitter are selected from a group of materials made up of KBr, KCl, NaCl, CsI, BaF, CaF and the like.

Abstract: A colorimetric sensor includes an etalon including a first substrate, a second substrate facing the first substrate, a fixed mirror formed on a surface of the first substrate facing the second substrate, and a movable mirror formed on the second substrate so as to face the fixed mirror with a prescribed gap therebetween, a light receiving element that receives a test subject light having passed through the etalon, and a holding member holding the etalon. The etalon includes a light interference area facing the first and second substrates in a plan view as seen in a thickness direction of the substrate, and a protruding area protruding from the light interference area. The holding member holds the etalon at one end side of the protruding area opposite to the light interference area.

Abstract: A variable wavelength interference filter includes a fixed substrate having a fixed reflecting film, a movable substrate having a movable reflecting film, and an electrostatic actuator including a fixed electrode and a movable electrode. The fixed electrode includes first and second fixed partial electrodes electrically isolated from each other. First and second extraction electrodes extending from the first and second fixed partial electrodes, respectively, are formed on the fixed substrate. The movable electrode is formed in a ring shape covering first and second facing regions facing the first and second fixed partial electrodes, respectively.

Abstract: The invention relates to optical low-coherence reflectometry with spectral reception and may be used for obtaining images without coherent noise caused by self-interference of the radiation scattered from the studied object and by spurious reflections in the optical path of the system. Two or more consecutive measurements of the interference spectrum are made. During at least one measurement of the interference spectrum by means of the interference control unit the phase between the interfering parts of the radiation is modulated by a certain law during exposure, which results in averaging and, hence, zeroing of the cross-correlation (useful) component of the registered spectrum, and during at least one additional measurement of the interference spectrum, the phase between the interfering parts of the radiation is not modulated during exposure. The phase between the interfering parts of the radiation may be set to be different in additional measurements of the interference spectrum.

Abstract: Systems and methods for performing spectral-spatial mapping in (one and two dimensions) and coded spectroscopy are described. At least one embodiment includes a system for performing spectral-spatial mapping and coded spectroscopy comprising a cylindrical beam volume hologram (CBVH), the CBVH configured to receive input beams and generate diffracted beams in a first direction to perform spectral-spatial mapping, the CBVH further configured to allow input beams to pass in a second direction orthogonal to the first direction unaffected. The system further comprises a first lens configured to receive the diffracted beams and perform a Fourier transform on the input beams in the first direction, a second lens configured to receive the diffracted beams and focus the beams in the second direction to generate output beams, and a charged coupled device (CCD) configured to receive the outputs beams, the output beams used to provide spectral analysis of the input beams.

Abstract: A spectroscopic ellipsometer comprising a light source (1) emitting a light beam, a polarizer (2) placed on the path of the light beam emitted by the light source, a sample support (9) receiving the light beam output from the polarizer, a polarization analyzer (3) for passing the beam reflected by the sample to be analyzed, a detection assembly which receives the beam from the analyzer and which comprises a monochromator (5) and a photodetector (4), and signal processor means (6) for processing the signal output from said detection assembly, and including counting electronics (13). Cooling means (12) keep the detection assembly at a temperature below ambient temperature, thereby minimizing detector noise so as to remain permanently under minimum photon noise conditions. It is shown that the optimum condition for ellipsometric measurement is obtained by minimizing all of the sources of noise (lamps, detection, ambient).