Abstract: A method includes directing a portion of a laser beam output from a laser along a secondary beam path toward a detector, the secondary beam path being distinct from a main beam path of the laser beam; generating a bandwidth selective interference pattern of the laser beam on the detector; detecting, at the detector, a width of a fringe within the interference pattern to thereby measure measuring a bandwidth of the laser beam; and homogenizing the laser beam traveling along the secondary beam path prior to generation of the bandwidth selective interference pattern. The homogenizing includes diffusing the laser beam; and introducing a time dependent, position dependent, or both time and position dependent random modulation to the wavefront of the laser beam to reduce fluctuations in the detected fringe width and to reduce the influence of spatial coherence of the laser beam on the detected interference pattern.

Abstract: A sensor and method for remotely determining a presence of a particular substance based on spectral data of the particular substance is disclosed.

Abstract: Disclosed is a system and method for characterizing optical materials, using steps and equipment for generating a coherent laser light, filtering the light to remove high order spatial components, collecting the filtered light and forming a parallel light beam, splitting the parallel beam into a first direction and a second direction wherein the parallel beam travelling in the second direction travels toward the material sample so that the parallel beam passes through the sample, applying various physical quantities to the sample, reflecting the beam travelling in the first direction to produce a first reflected beam, reflecting the beam that passes through the sample to produce a second reflected beam that travels back through the sample, combining the second reflected beam after it travels back though the sample with the first reflected beam, sensing the light beam produced by combining the first and second reflected beams, and processing the sensed beam to determine sample characteristics and properties.

Abstract: A wavelength-variable interference filter includes first and second electrodes provided at first and second substrates, respectively, the second substrate including a movable section, first and second electrode wires that extend from the first and second electrodes toward outer circumferential edges of the first and second substrates, respectively, a first opposite electrode wire disposed so as to be isolated from the second electrode, and a first conductive section that connects the first electrode wire with the first opposite electrode wire. The second electrode wire and the first opposite electrode wire extend passing through a center point of an imaginary circle of the movable section in respective directions and dividing the imaginary circle at regular angular intervals.

Abstract: An apparatus includes a single or dual output port, dual-drive Mach-Zehnder Interferometer configured to generate a first optical signal in one path, and to generate a second optical signal in a different path. The apparatus also includes an optical spectrum analyzer configured to receive output from at least one port of the dual-drive Mach-Zehnder Interferometer. A method includes causing radio frequency signals from two different antennae to modulate an optical carrier at a corresponding drive of a dual-drive Mach-Zehnder Interferometer, and causing output from at least one port of the Mach-Zehnder Interferometer to be directed to an optical spectrum analyzer. The method further comprises determining arrival angle at each of a plurality of frequencies in the radio frequency signals based on output from the optical spectrum analyzer.

Abstract: A spectrometer includes: a tungsten lamp which emits light with no peak wavelength within a wavelength range of visible light and having a light amount increasing as the wavelength becomes longer; a violet LED which emits light having a peak wavelength within the wavelength range of visible light; a light mixer which mixes light emitted from the tungsten lamp and the violet LED; an etalon which receives light mixed by the light mixer and transmits light contained in the received mixed light and having a particular wavelength; a light receiving unit which receives light transmitted by the etalon; and a measurement control unit which changes the wavelength of light that can pass through the etalon and measures spectral characteristics of the light having passed through the etalon based on the light received by the light receiving unit.

Abstract: An optical device includes a telecentric optical system, a variable wavelength interference filter, and a detection section, the variable wavelength interference filter includes a first reflecting film, a second reflecting film provided to a movable section, and an electrostatic actuator adapted to displace the movable section, an effective measurement area capable of transmitting a light with a wavelength, which is within a predetermined allowable range centered on a measurement center wavelength when an amount of the displacement of the movable section takes a maximum displacement value, is set in the first reflecting film and the second reflecting film, and the telecentric optical system guides the incident light to the variable wavelength interference filter so that a principal ray of the incident light is parallel thereto and perpendicular to the first reflecting film, and at the same time, collects the incident light in the effective measurement area.

Abstract: A method for detecting motion direction of an object (4) comprises the steps of: laser output light (L1) is generated, using a semiconductor laser (2) having a thermal response frequency (fr); the laser is driven with rectangularly modulated DC current (I) having a modulation frequency higher than said thermal response frequency (fr) and preferably higher than twice said thermal response frequency (fr), such as to triangularly modulate the wavelength of the laser output light; the laser output light is directed to the object; a portion of reflected light (L3) is allowed to interfere with light (L0) within the laser; a portion of the laser light is used as measuring beam (5); the frequency spectrum of the measuring beam (5) is analyzed in conjunction with the modulated laser current in order to determine the direction of movement of the object (4).

Abstract: A Sagnac interferometer can include a beamsplitter arranged to receive an input beam of light of a design wavelength, to split the input beam of light into first and second beams that counter propagate around an optical path, and to recombine the first and second beams into an output beam of light. The optical path can include at least one diffraction grating that is arranged to satisfy an effective Littrow geometry.

Abstract: The present invention offers an alternative strategy for the correlation of interference information to chemical and/or physical properties of a sample. This strategy can be implemented in a method and a system, which offer substantial technical and commercial advantages over state of the art techniques based on interference spectroscopy. The invention further provides a method for standardizing an interferometer, as well as a method and a system using the standardized interferometer.

Abstract: A multiband spatial heterodyne spectrometer for determining spectra in first and second wavelength bands has a beam splitter configured to split incident light and to direct the incident light upon a first and a second diffraction grating. The gratings are configured for Littrow reflection of incident light of the first wavelength band at a first order and Littrow reflection of incident light of the second wavelength band at a second order. Light reflected by the first and the second diffraction grating forms diffraction patterns that are imaged by an electronic camera. A dispersive device such as a prism or diffraction grating separates the imaged interference patterns onto separate rows of pixel sensors corresponding to the wavelength bands. A processing device receives information from the detector and computes spectra therefrom. In embodiments, the spectrometer is configured to compute hyperspectral images of a target.

Abstract: The method and device for measuring the spectral phase or combined spectral and spatial phases of ultra short light pulses, consisting of a decomposition of the light pulse to be measured in two identical replicas called signal pulse and primary reference pulse, respectively, of different polarization or direction and the phase characteristics of which are essentially identical to the original pulse, a temporal filtering of the primary reference pulse by a nonlinear interaction generating a secondary reference pulse of average frequency essentially identical and of spectral width greater than the spectral width of the primary reference pulse, and a spectral interferometry measurement by recombination of this secondary reference pulse and the signal pulse with a given temporal offset.

Abstract: An absorption spectrometer provides improved rejection of background radiation signal by employing a frequency-swept laser signal without frequency dithering and performing an effective differentiation of output light from a test cell to eliminate these constant or slowly varying background radiation levels.

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 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 terahertz spectrometer includes: a terahertz-wave emitter and a terahertz receiver elements. The terahertz wave generated by means of generating beat frequency corresponding to the difference between two rapidly tunable continuous wave lasers. Having a difference in time between the interrogating signal and the reference signal at the receiver end side, which corresponds to intermediate frequency (IF), not centered around the baseband, i.e. zero Hertz. The offset step size of the intermediate frequency from zero Hertz is linearly correlated to the position of the interrogated object position.

Abstract: The invention relates to scanning pulsed laser systems for optical imaging. Coherent dual scanning laser systems (CDSL) are disclosed and some applications thereof. Various alternatives for implementation are illustrated, including highly integrated configurations. In at least one embodiment a coherent dual scanning laser system (CDSL) includes two passively modelocked fiber oscillators. The oscillators are configured to operate at slightly different repetition rates, such that a difference ?fr in repetition rates is small compared to the values fr1 and fr2 of the repetition rates of the oscillators. The CDSL system also includes a non-linear frequency conversion section optically connected to each oscillator. The section includes a non-linear optical element generating a frequency converted spectral output having a spectral bandwidth and a frequency comb comprising harmonics of the oscillator repetition rates.

Abstract: A monolithic frame for optics used in interferometers where the material of the monolithic frame may have a substantially different coefficient of thermal expansion from the beamsplitter and compensator without warping, bending or distorting the optics. This is accomplished through providing a securing apparatus holding the optics in place while isolating the expansion thereof from the expansion of the frame. Stability in optical alignment is therefore achieved without requiring a single material or materials of essentially identical coefficients of thermal expansion. The present invention provides stability in situations where it is not possible to utilize a single material for every component of the interferometer.

Abstract: Raman spectroscopy apparatuses are described that detect the spectral characteristics of a sample wherein the apparatus consists of a multiplicity of modulated discrete light sources adapted to excite a sample with electromagnetic radiation, a filter adapted to isolate a predetermined wavelength emitted by the sample wherein the wavelength is further modulated at different frequencies, and a detector for detecting the isolated wavelength. The apparatus may further consist of an interferometer, such as a Michelson interferometer, adapted to modulate the excitation energy. Also provided herein are methods, systems, and kits incorporating the Raman spectroscopy apparatus.

Abstract: A Fourier transform spectrometer (FTS) data acquisition system includes an FTS spectrometer that receives a spectral signal and a laser signal. The system further includes a wideband detector, which is in communication with the FTS spectrometer and receives the spectral signal and laser signal from the FTS spectrometer. The wideband detector produces a composite signal comprising the laser signal and the spectral signal. The system further comprises a converter in communication with the wideband detector to receive and digitize the composite signal. The system further includes a signal processing unit that receives the composite signal from the converter. The signal processing unit further filters the laser signal and the spectral signal from the composite signal and demodulates the laser signal, to produce velocity corrected spectral data.

Abstract: A spectral interferometry apparatus and method are disclosed, that can be used to monitor or measure an unknown length by following a characteristic of an indicating signal. The measurement is performed by adjusting an optical path difference (OPD) in an interferometer part of an interferometer configuration until sound or light or both are obtained with the desired strength and pitch. Embodiments are presented where the unknown length is the eye length. Spectral interrogation of the interferometer optical output is achieved by reading the signal of an analogue photodetector array in a spectrometer or by tuning a swept source and processing the signal of a photodetector. Sound of different pitches are produced either directly in this process, or by using a nonlinear amplifier, or a mixer. For enhanced signal, the array may be driven by a nonlinear clock or the swept source may be driven by a distorted driving signal.

Abstract: A device for optical sensing of substances or environmental conditions in a fluid includes a number of non-overlapping adjacent sensing elements, each having a layered optical element for generating a wavelength-specific interference effect and being treated so as to respond to the presence of a predefined substance or a predefined environmental condition to cause an optically detectable change. The sensing elements are distinct from each other both in their wavelength-specific interference effect and in the corresponding optically detectable change. As a result, when the device is illuminated by a common illumination beam of multi-wavelength illumination, spectral analysis performed on the reflected or transmitted illumination enables simultaneous sensing of a plurality of substances or environmental conditions. In certain preferred implementations, the layered optical element includes at least one layer of porous silicon.

Abstract: A transform spectrometer implemented on a planar waveguide circuit (PLC), having an input optical signal waveguide carrying an input optical signal to be analyzed; 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. An array of interleaved, asymmetrical waveguide Mach-Zehnder interferometers (MZI) is formed on the PLC, each having at least one input MZI waveguide, each MZI input waveguide receiving a coupled optical signal from a respective coupler output; wherein at least some of the input MZI waveguides intersect in a common layer of the PLC, at an angle which allows their respective coupled optical signals to transmit without unacceptable attenuation. This arrangement improves spatial efficiency of the PLC, allowing more MZIs to be implemented, resulting in increased spectral resolution.

Abstract: The invention relates to apparatus and methods for assessing occurrence of a hazardous agent in a sample by performing multipoint spectral analysis of the sample. Methods of employing Raman spectroscopy and other spectrophotometric methods are disclosed. Devices and systems suitable for performing such multipoint methods are also disclosed.

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 method is presented for selecting the order in which parameters are evaluated for inclusion in a model of a film stack, which is by ranking them according to measurement precision. Further, a method is presented for determining which parameters are to be floated, set, or discarded from the model, which is by determining whether average chi-square and chi-square uniformity decreases or increases when the parameter is added to the model. In this manner, a model for the film stack can be quickly assembles with a high degree of accuracy.

Abstract: An imaging apparatus includes: a solid-state imaging device including a semiconductor substrate, a plurality of photoelectric conversion elements provided in the semiconductor substrate and a spectral element which is provided over the plurality of photoelectric conversion elements that are consecutive in a straight-line manner, in which a trapezoidal opening longitudinal in a direction from a bottom side into which light incident on the plurality of photoelectric conversion elements is introduced to a top side is provided, and which makes a spectral separation occur in the longitudinal direction by interference between the incident light and light reflected from an inner side surface of the trapezoidal opening; and a polarizing element which is provided on an optical path from a photographic subject to the solid-state imaging device and which allows polarized light to be transmitted therethrough.

Abstract: Systems and methods for a compact Fourier transform spectrometer. A cell having two transparent walls and containing a liquid crystal medium is placed in a light beam. Applying a voltage across the cell causes the liquid crystal molecules to orient at a certain angle, wherein the angle is a function of the voltage applied. The refractive index if the cell is dependent upon the orientation of the liquid crystal molecules, and from the refractive index of the cell an optical path difference between ordinary and extraordinary waves can be calculated. Accordingly, any suitable optical path difference can be achieved by varying the voltage across the cell for a Fourier transform analysis.

Abstract: A device for the interferometric measurement of a sample, in particular the eye, including an interferometer arrangement with a first measurement beam path, through which a measurement beam falls onto the sample, and a first reference beam path, through which a reference beam runs, which is applied to the measuring beam for interference. The interferometer arrangement includes a second measuring beam path and/or second reference beam path. The optical path lengths of the second measuring beam path and/or second reference beam path are different from one of the first beam paths. The wave length difference is selected according to a distance of two measuring areas which are arranged at a distance in the depth direction of the sample.

Abstract: Disclosed are optical sensing devices and methods for detecting samples using the same. The optical sensing device comprises a source unit configured to generate a polychromatic light beam containing p-polarized and s-polarized components; an interferometric unit configured to split the light beam into a probe beam passing a first path and a reference beam passing a second path and to recombine the probe beam output from the first path and the reference beam output from the second path; a sensing unit disposed in the first path to introduce a first SPR effect associated with a target sample to the probe beam; and a detection unit configured to detect target sample characteristics by obtaining an intensity spectrum of the recombined light beam. The introduction of a polychromatic light source in the optical sensing device increases the detection dynamic range and the detection sensitivity.

Abstract: Disclosed is an apparatus and method for obtaining images using coherent anti-stokes Raman scattering. The apparatus for obtaining images using coherent anti-stokes Raman scattering according to the present invention comprises: a pump light source and a stokes light source that irradiate pump light and stokes light on a sample to generate anti-stokes light having anti-stokes frequency; a reference light source that generates reference light; and an image obtaining unit that obtains the images of the sample using a change in phase of the reference light due to a change in the refractive index of the sample in the vicinity of the anti-stokes frequency. Thereby, the present invention can provide the apparatus for obtaining images using coherent anti-stokes Raman scattering that is not affected by a non-resonant background signal phenomenon, strong resistance against noise even in a weak signal, and has excellent sensitivity and resolution.

Abstract: A spectroscopy wavelength and amplitude referencing system comprises an optical bench receiving a tunable optical signal from a tunable signal source, a wavelength reference detector on the bench for determining a wavelength of the tunable optical signal, an amplitude reference detector on the bench for determining an amplitude of the tunable optical signal and an output optical signal fiber for transmitting the tunable optical signal to a sample. Also, spectroscopy system controller determines a spectral response of the sample to the tunable optical signal by determining an instantaneous wavelength of the tunable optical signal by reference to the wavelength reference detector.

Abstract: An embodiment relates to an interferometer comprising: a first frequency comb; a second frequency comb adapted to interact with the first frequency comb in order to produce interferences; means for isolating the beating signal between a subset of frequency components among the frequency components of the two combs. This subset of frequency components may be preferably, but not necessarily, a single line of the first frequency comb and a single line of the second frequency comb; means for monitoring this beating signal and using it as a trigger or as a clock for the acquisition unit device recording the beating interference signal between the entire frequency components of the first and the second frequency combs.

Abstract: An embodiment relates to a Fourier transform spectrometer comprising: a coherent light source; an interferometer adapted to separate the coherent light source into two or more parts in order to generate through frequency or phase-induced effects, interferences between the two or more parts; detection means adapted to detect the interferences, wherein the coherent light source comprises a frequency comb generator having a frequency repetition rate, and the detection means are adapted to detect the beating of pairs of frequencies of the frequency comb separated by the frequency repetition rate or a multiple of the frequency repetition rate.

Abstract: The disclosure is directed at an interferometric localized surface plasmon resonance sensor (ILSPR) unit comprising an ILSPR sensor chip, the sensor chip including a localized surface plasmon resonance sensor (LSPR) layer; at least one light source for directing light through the ILSPR sensor chip at the LSPR layer; and a photodetector for sensing a level of light intensity after the light has struck the LSPR layer.

Abstract: The invention relates to a wavelength spectroscopy device comprising, on a substrate a filter cell CF constituted by two mirrors separated by a spacer membrane, the filter cell being made up of a plurality of interference filters. Furthermore, the device also comprises an emission cell CE comprising a plurality of emission sources, each of said sources being associated with one of said interference filters.

Abstract: The present invention relates to a measurement method of the chromatic dispersion of an optical waveguide using an optical interferometer with a broadband multi-wavelength light source and an optical spectrum analyzing apparatus, wherein one arm, called “reference arm” of the interferometer's two arms has an adjustable air spacing and the other arm, called “sample arm” can contain said optical waveguide to be measured, and including the following measurement and analysis steps: measuring interference spectra of the optical beam output exiting from the said interferometer with an optical spectrum analyzing apparatus when said optical waveguide is connected to said sample arm, and when said optical waveguide is not connected to said sample arm respectively; by adjusting the reference arm length for appearance of clear interference patterns; converting the wavelength-domain interference spectra into frequency-domain interference spectra and calculating phase difference values of the interference peaks of one of

Abstract: An apparatus for detecting vulnerable plaque within a lumen defined by an intraluminal wall is described. The apparatus includes a probe having a distal portion and a proximal portion. The apparatus includes an optical waveguide extending along the probe. The optical waveguide is configured to carry optical radiation between the distal and proximal portions, and has a distal end in communication with the intraluminal wall. The apparatus includes an interferometer coupled to the optical waveguide and configured to provide an interference signal for sub-surface imaging of the intraluminal wall, and a processing module configured to provide spectroscopic information from detected intensity of light collected from the intraluminal wall.

Abstract: A method and an arrangement are provided for scalable confocal interferometry for distance measurement, for 3-D detection of an object, for OC tomography with an object imaging interferometer and at least one light source. The interferometer has an optical path difference not equal to zero at each optically detected object element. Thus, the maxima of a sinusoidal frequency wavelet, associated with each detected object element, each have a frequency difference ?f_Objekt. At least one spectrally integrally detecting, rastered detector is arranged to record the object. The light source preferably has a frequency comb, and the frequency comb differences ?f_Quelle are changed in a predefined manner over time in a scan during measuring. In the process, the frequency differences ?f_Quelle are made equal to the frequency difference ?f_Objekt or equal to an integer multiple of the frequency differences ?f_Objekt at least once for each object element.

Abstract: The concentration of impurities contained in ultrapure water or press water can be efficiently analyzed with high precision. A portion of a liquid to be measured is introduced into an absorption spectrometric portion from a predetermined line. The liquid is irradiated with exciting light from an exciting light irradiation system, and a measurement object region in which a photothermal effect of the impurities in the liquid is produced by the irradiation is irradiated with measuring light from a measuring light irradiation system. A change in phase of the measuring light is detected by a predetermined optical system and a photodetector, and the impurity concentration in the liquid is determined on the basis of the change in phase.

Abstract: A method and system for nuclear substance revealing using muon detection technique is presented. In some aspects, naturally occurred muons are selected from the flow of charged particles. Muon coordinate and incidence angle measured above and below the interrogated volume can be used for the decision making on the presence of nuclear substance inside the volume. The system is adapted for performing measurements on moving objects such as moving trucks. A combination of the nuclear substance detection system with an explosive sensing system is presented.

Abstract: An optical broadband micro-spectrometer containing an input optical assembly, a group of slab waveguide spatial heterodyne spectrometer (SHS) integrated circuits (ICs), a detection module and a processor for multi-line detection. The input optical assembly applies an input light signal uniformly with respect to brightness and frequency to the apertures of the waveguides and may project a pupil image onto the SHS input face and may be a scanner. Each slab waveguide spatial heterodyne spectrometer (SHS) integrated circuit (IC) contains at least one slab waveguide SHS IC. The detection module bonds directly to the slab waveguide output apertures. Each slab waveguide SHS IC may contain one or more slab waveguide SHS.

Abstract: A spectrometric system has a primary channel with a signal waveform and a reference channel with a signal waveform. A digital representation of the primary signal waveform and a digital representation of the reference signal waveform to provide a digital output representing the primary signal at datum points synchronized with the reference signal are processed by computing the Fourier transform of the primary signal waveform and using a fast reverse non-uniform discrete Fourier Transform technique to compute the reverse non-uniform discrete Fourier transform of the Fourier transform of the primary signal waveform to provide the digital output representing the primary signal at datum points synchronized with the reference signal.

Abstract: A photo-thermal, interferometric spectroscopy system is disclosed that provides information about a chemical, such as explosives and the like, at a remote location. It may be used for solid residue detection on a surface. The system includes a novel light detector system with a matrix of optical elements focusing portions of a received light beam on input waveguides of an optical combiner. The combiner adjusts the phases of the received beam portions and combines them together to maximize the intensity of an output beam. The output beam is detected by a detector, and information about at least one of, absorption spectrum and concentration of the chemical is recovered. In the preferred embodiment the detector is a coherent detector based on 90-degrees optical hybrid.

Abstract: Embodiments described herein provide a method and apparatus for obtaining process information in a substrate manufacturing process using plasma. In one embodiment, a chamber is provided having one or more optical metrology modules that are positioned such that optical energy from the plasma process is detected at substantially orthogonal angles. Metrics derived from detected optical energy may be used for endpoint determination, substrate temperature, and monitoring of critical dimensions on the substrate.

Abstract: This invention relates generally to the systems and methods for chemicals detection such as explosives and others, and more particularly to optical devices and the methods of their use based on sensing of gases and residue materials. This sensing includes detection of optical spectrum and relative concentration of the chemical followed by the chemical identification based on these data. The sensing is based on photothermal interferometry method modified by implementation of coherent optical detection using a balanced receiver, where the incoming optical signal is mixed with a local oscillator beam. An additional phase shift is embedded in the local oscillator beam for adaptively negating the background noise in the incoming optical signal thus improving the system performance.

Abstract: The invention relates to a spectrograph (11) comprising a waveguide (10) provided with accesses (10; 10b, 12), a means for injecting two guided contra-propagative waves by each accesses in such a way that a spatial interference is formed in the waveguide, means (19, 20, 14, 16) for detecting the energy of the evanescent wave of the guided field produced by the interference of said contra-propagative waves.

Abstract: A monolithic frame for optics used in interferometers where the material of the monolithic frame may have a substantially different coefficient of thermal expansion from the beamsplitter and compensator without warping, bending or distorting the optics. This is accomplished through providing a securing apparatus holding the optics in place while isolating the expansion thereof from the expansion of the frame. Stability in optical alignment is therefore achieved without requiring a single material or materials of essentially identical coefficients of thermal expansion. The present invention provides stability in situations where it is not possible to utilize a single material for every component of the interferometer.

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: An absorption spectrometer provides improved rejection of background radiation signal by employing a frequency-swept laser signal without frequency dithering and performing an effective differentiation of output light from a test cell to eliminate these constant or slowly varying background radiation levels.