Abstract: Methods and designs for providing reduced sensitivity to mirror tilt in Fourier transform spectrometers are disclosed. According to an embodiment for two-directional tilt compensation, the FT spectrometer can include a beam splitter positioned to receive an incoming beam from a light source and split the incoming beam into a first sub-beam and a second sub-beam, a corner-cube retroreflector positioned to receive the first sub-beam from the beam splitter, a dual reflective mirror positioned to receive the first sub-beam from the corner-cube retroreflector at one surface and the second sub-beam at the other surface. An optical path delay can be created using a set of mirrors, tilting the beam splitter and/or a glass cube.

Abstract: A micro-lamellar grating interferometer for deriving the spectrum of an incident beam from a scene of interest from a generated interferogram is disclosed with a method for using the same. The interferometer comprises a lamellar grating defined by two interleaved reflective mirror set; a first stationary set of electromagnetically reflective elements and a second moveable set of electromagnetically reflective elements. The first and second set of electromagnetically reflective elements are referred to as mirror elements herein. The second mirror element set is disposed on a moveable platform supported by flexures that are driven with a high stiffness magnetic, thermal or piezoelectric actuator designed have a predetermined vertical displacement that is perpendicular to the first mirror set.

Abstract: An interferometer includes a variable optical path length reference mirror to produce a final interferogram from a combination of interferograms. Each of the interferograms is generated at a different optical path length of the reference mirror.

Abstract: An interferometer system includes an optical bench and at least two mirror structures, being patterned from one or more layers on the optical bench and erected to extend substantially perpendicularly to the bench to define two interferometer arms to provide a Micro-Electro-Mechanical Systems (MEMS) interferometer. The MEMS interferometer is further implemented in a Fourier transform spectrometer, which includes a common housing containing the interferometer and a gas cell, possibly including a preconcentrator.

Abstract: An interferometer system includes an optical bench and at least two mirror structures, being patterned from one or more layers on the optical bench and erected to extend substantially perpendicularly to the bench to define two interferometer arms to provide a Micro-Electro-Mechanical Systems (MEMS) interferometer. The MEMS interferometer is further implemented in a Fourier transform spectrometer, which includes a common housing containing the interferometer and a gas cell, possibly including a preconcentrator.

Abstract: A Micro-Electro-Mechanical Systems (MEMS) interferometer is implemented in a Fourier transform spectrometer, which includes a common housing containing the interferometer and a gas cell, possibly including a preconcentrator. The interferometer system includes an optical bench and at least two mirror structures, being patterned from one or more layers on the optical bench and erected to extend substantially perpendicularly to the bench to define two interferometer arms to provide a MEMS interferometer.

Abstract: The invention relates to a Fourier transform spectrometer comprising a binary grating with variable depth, the grating comprising a first set of mirrors and a second set of mirrors, the mirrors of the first set of mirrors and the mirrors of the second set of mirrors being arranged in an alternating order and at least one of the sets of mirrors being carried by fingers of a comb structure of a wafer, the spectrometer further comprising an actuator for prompting a motion of the second set of mirrors and a detector for detecting a radiation reflected by the grating, the mirrors being orientated in a plane defined by said wafer and said motion of the second set of mirrors being given by a translation in a direction vertical to said wafer plane.

Abstract: A microscope comprising: a light sampler for collecting light from a measurement area of a sample; a multi-element detector having a plurality of photoelectric elements, for detecting the light collected by the light sampler, each photoelectric element corresponding to a minute measurement region in the measurement area with one-to-one correspondence; a Fourier transform spectrophotometer as a spectroscope; a data sampler for concurrently sampling intensity data sent from each photoelectric element of the multi-element detector at a timing determined by the Fourier transform spectrophotometer; and a data processor for obtaining time-resolved spectrum data for each minute measurement region according to temporally changed interference light data obtained by the data sampler.

Abstract: A device in miniature and fabrication of such a device for interferometric use is described, the device including a substrate with at least one deep reactive ion etching structure on at least one surface of the substrate forming an optical bench. The optical bench preferably comprises a moving stage, an actuator, one or more connector sockets and one or more optical components.

Abstract: The Miniature Fourier Transform Spectrophotometer provides the capability, in a miniaturized device, of determining the light absorption/transmission spectra of a collected sample of gas or liquid though Fourier Transform spectroscopy techniques. The device takes an optical input from an optical fiber, manipulates that light through miniature optical components, and launches it into a miniaturized Michelson interferometer with a scanning mirror that acquires the interferogram of the optical input. The interferogram can be processed to retrieve the spectrum of the input light. A novel multi-stepped micro-mirror operates as the optical path length modulator in the miniaturized interferometer. A unique monolithic beamsplitter/mirror combination provides for accurate alignment of the components and greatly simplifies product integration. The device is designed to cover various optical spectra of interest.

Abstract: A device in miniature and fabrication of such a device for interferometric use is described, the device including a substrate with at least one deep reactive ion etching structure on at least one surface of the substrate forming an optical bench. The optical bench preferably comprises a moving stage, an actuator, one or more connector sockets and one or more optical components.

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.

Abstract: An optical signal is copressively sampled using an imaging system. The imaging system is created from a plurality of subimaging systems. Each subimaging system comprises a subaperture and a plurality of sensors. The optical signal is collected at each subaperture of the plurality of subimaging systems at a single time step. The optical signal is transformed into a subimage at each subimaging system of plurality of subimaging systems. The subimage includes at least one measurement from a plurality of sensors of each subimaging systems. An image of the optical signal is calculated from the sampling function and each subimage, spatial location, pixel sampling function, and point spread function of each subimaging system of the plurality of subimaging systems. The sampling function is selected so that the number of measurements from a plurality of subimages is less than a number of estimated optical signal values in the image.

Abstract: Real time high speed high resolution hyper-spectral imaging.

Abstract: The cavity in the mirror arm of a conventional interleaver is replaced by a wedge integral with the beamsplitter structure of the interleaver. Thus, the light reflected from the AR-coated surface of the wedge is dispersed away from the optics of the device. The beam emerging from the wedge surface is directed toward a tilted mirror that reflects it totally on-axis. As a result of the diversion of the light reflected from the wedge surface and the non-parallel disposition of the wedge surface with respect to the mirror, phase errors are virtually eliminated. In another embodiment, a second wedge is used with a second antireflective surface disposed in parallel to the first wedge's antireflective surface, and with a mirror normal to the optical axis of the device.

Abstract: The Miniature Fourier Transform Spectrophotometer provides the capability, in a miniaturized device, of determining the light absorption/transmission spectra of a collected sample of gas or liquid though Fourier Transform spectroscopy techniques. The device takes an optical input from an optical fiber, manipulates that light through miniature optical components, and launches it into a miniaturized Michelson interferometer with a scanning mirror that acquires the interferogram of the optical input. The interferogram can be processed to retrieve the spectrum of the input light. A novel multi-stepped micro-mirror operates as the optical path length modulator in the miniaturized interferometer. A unique monolithic beamsplitter/mirror combination provides for accurate alignment of the components and greatly simplifies product integration. The device is designed to cover various optical spectra of interest.

Abstract: An arrangement for building a compact Fourier transform interferometer for optical radiation according to the Michelson principle or a principle derived therefrom. According to the invention, this arrangement is characterized in that the optical modulation of the radiation in at least one of the interferometer arms is produced by the translational displacement of micromechanical translation mirrors that are optically accessible on one side or on both sides, with an effective oscillation amplitude of at least 50 ?m and a usable mirror surface area of at least 1 mm2. In doing so, the micromechanical mirror components according to the invention assume the function of known movable mirrors so that by using an almost massless microcomponent in comparison to conventional systems, a much smaller size and a mirror modulation frequency that is several orders of magnitude higher can be achieved. The arrangement according to the invention is used especially for optical spectroscopy.

Abstract: A transmission mask or cooled aperture is used in spectroscopy to compressively sample an optical signal. The locations of transmissive and opaque elements of the mask are determined by a transmission function. The optical signal transmitted by the mask is detected at each sensor of a plurality of sensors dispersed spatially with respect to the mask. A number of estimated optical signal values is calculated from sensor measurements and the transmission function. The optical signal is compressed by selecting the transmission function so that the number of measurements is less than the number of estimated optical signal values. A reconstructed optical signal is further calculated using signal inference. An imaging system created from plurality of encoded subimaging systems compressively samples an optical signal.

Abstract: An FT-IR microscope is operated in association with a scanning spectrometer in such a way that incremental movement of the movable stage of the microscope is synchronized with the scans of the scanning spectrometer. This minimizes delays in processing time.

Abstract: The tilt-compensated interferometers of the present invention are novel variations of Michelson's interferometer that use tilt- and shear-compensation to provide excellent photometric accuracy even when there are imperfections in the scanning motion used to produce variation of path difference. The tilt-compensation mechanism of the present invention consists of antiparallel reflections from a beamsplitter element and a roof reflector element, which elements are held rigidly in alignment. Several particularly useful embodiments of the invention are described. Other advantages of the present invention include photometric stability and reduced cost because manual alignment is not required. This interferometer has applications in spectrometry, spectral imaging and metrology.

Abstract: A wavelength stabilized laser module is provided which is so configured as to be simplified and smaller in size and is capable of emitting semiconductor laser light whose wavelength is stablized with high accuracy. The wavelength stablized laser module includes a semiconductor laser, a substrate, a lens to convert emitted semiconductor laser light to parallel luminous flux, a first photoelectric converter to receive a part of the parallel luminous flux and to convert it to electric signals, a filter to receive a part of the parallel luminous flux, a second photoelectric converter to receive light transmitted through the filter and to convert it to electric signals, wherein a control signal to be used for stabilization obtained by computations of electric signals fed from the converters is fed back to the semiconductor laser device and/or the substrate so that said semiconductor laser is able to stably emit laser light having a reference wavelength to be used as a target for stabilization.

Abstract: The present invention is a cost-effective and compact micro-spectrometer for rapid detection of chemical compounds in the low concentration limit. The invention provides for significantly higher sensitivity compared to conventional spectroscopy techniques (continuous wave and Fourier transform methods) by placing the sample within a high Finesse etalon cavity. An Optical Spectrum Analyzer (OSA) built on either continuous wave (CW-SPEC), or Fourier Transform Absorption Spectroscopy (FT-SPEC) is used to monitor the spectrum from the etalon cavity/sample combination during tuning of the etalon cavity˜this information is then used to reconstruct the absorption spectrum.

Abstract: A linear positioning apparatus includes an intermediate portion having an axis, and first and second end portions mounted with flexure legs thereto. The flexure legs accommodate motion of the intermediate portion relative to the end portions along the axis, but inhibit motion of the intermediate portion relative to the end portions in directions not parallel to the axis. The apparatus can accommodate forces having off-axis components, and produce motion that comprises substantially no off-axis component. The apparatus is useful in, for example, optical systems where precise linear motion is required.

Abstract: The present invention is a method and an apparatus for identifying and quantifying components in an effluent stream from an ammoxidation reactor, the apparatus comprising a microprocessor; and a Fourier Transform infrared spectrometer having a sample cell through which may flow a portion of the effluent stream, an infrared source to emit infrared radiation and pass the infrared radiation through the effluent stream, an infrared detector to detect transmitted infrared radiation at the selected infrared wavelengths and to generate absorbance data due to absorbance of the infrared radiation by the components, wherein each of the components absorbs infrared radiation at one or more of the infrared wavelengths, and an output apparatus to provide the absorbance data to the microprocessor; wherein the microprocessor is programmed to identify and quantify each of the plurality of components based upon the absorbance data and calibration data, the calibration data being obtained from recovery run analyses and calibrat

Abstract: A multifunctional infrared spectrometer system has an interferometer which receives the infrared beam from a source and provides a modulated output beam on beam paths to multiple spatially separated infrared detectors. A multi-position mirror element mounted at a junction position receives the beam on a main beam path and directs it on branch beam paths to sample positions, with the beam then being directed on the branch beam path to one of the detectors. One of the branch beam paths may include a sample holder at the sample position which can index between a position at which a sample is analyzed, to a reference material position, to a pass-through position for calibration purposes.

Abstract: An optical part driving device for moving an optical part, comprises; a driving timing pulley, a pair of driven timing pulleys, a timing belt wound by the driving timing pulley and the driven timing pulleys and connected with the optical part between the pair of driven timing pulleys, and a pair of tension pulleys for tensing the timing belt on both sides of the driving timing pulley.

Abstract: Fringe counting in a Michelson type interferometer is carried out by detecting when the amplitude of the reference fringe attains a given value eg a zero crossing. Reversals in scan direction are recognized by monitoring parameters of the waveform such as amplitude and time occurence of successive half fringes and identifying a reversal by the occurrence of a particular sequence or state of the monitored parameters.

Abstract: The present invention provides a wavemeter for an ultraviolet laser capable of long life beam quality monitoring in a pulsed ultraviolet laser system at pulse rates greater than 2000 Hz at pulse energies at 5 mJ or greater. In a preferred embodiment an enhanced illumination configuration reduces per pulse illumination of an etalon by a factor of 28 compared to a popular prior art configuration. Optics are provided in this embodiment which reduce light entering the etalon to only that amount needed to illuminate a linear photo diode array positioned to measure interference patterns produced by the etalon. In this preferred embodiment two sample beams produced by reflections from two surfaces of a beam splitter are diffused by a defractive diffuser and the output of the defractive diffuser is focused on two separate secondary diffusers effectively combining both beams in two separate spectrally equivalent diffuse beams.

Abstract: An optical interferometer in which a reference light and a light to be measured interfere with each other includes a casing, a movable optical part which is movable with respect to the casing, a fixed optical part which is fixed to the casing, and an attachment emember for attaching the movable optical part to the casing and for removing the movable optical part form the casing.

Abstract: A feedback position control system and method enable an optical element in a variable arm of an interferometer to be varied according to a predesignated motion profile. The system and method detect a reference optical signal that varies in intensity according to a position of the optical element in the variable arm. The system and method receive the detected reference optical signal, derive a motion profile from the detected reference optical signal and compare the derived motion profile to the predesignated motion profile to generate a control signal based on a deviation between the derived motion profile and the predesignated motion profile. The control signal is used to adjust the position of the optical element in the variable arm of the interferometer to minimize the deviation between the derived motion profile and the predesignated motion profile.

Abstract: A linear translation apparatus for optical systems has a tube and a piston that slides along an inner wall of the tube that is disposed about a longitudinal axis. An optical element mounted on the piston intercepts optical signals entering the tube so that optical path lengths within the optical system are varied as the piston moves along the longitudinal axis. The piston has a magnetic moment enabling the piston to slide along the inner wall in response to the strength and direction of a magnetic field generated by a magnetic actuator. A driver coupled to the magnetic actuator establishes the strength and direction of the generated magnetic field to achieve a predesignated motion profile for the piston along the longitudinal axis.

Abstract: A multiple spring support for a displaceable mirror in an interferometer maintains the plane in which the flat mirror surface resides perpendicular to the centerline of a wave front at all retardations of the interferometer. In its simplest configuration, two equal length spring sections are connected to a movable rigid beam section at one end of the spring sections and are connected to a fixed rigid base section at the other end of the spring sections. The spacing between spring sections at the movable rigid beam section being the same as the spacing between spring sections at the fixed rigid base section.

Abstract: A wavelength meter for measuring the wavelength of an input light signal. The meter includes a beam splitter, a fixed mirror, and a moveable mirror, the beam splitter splits the input signal into a first input signal and a second input signal, the first and second input signals being reflected from the fixed and moveable mirrors, respectively, and being recombined by the beam splitter. The first reference light signal is reflected by the fixed mirror and the second reference light signal is reflected by the moving mirror, the beam splitter recombines the first and second reference light signals to form a combined reference light signal. The amplitude of the combined reference light signal is detected by a reference detector that generates a reference signal related to the amplitude of the combined reference light signal.

Abstract: A stage apparatus on which a laser interferometer is mounted includes a reticle stage (1) movable in three, X-, Y-, and &thgr;-axes, laser heads (8a-8d) each for generating a laser beam, interferometers (9a-9d) each of which is mounted on the stage (1) and splits the laser beam into reference and measurement beams, bar mirrors (11a-11c) each of which is arranged outside the stage (1) and reflects the measurement beam, and detectors (10a-10c) each for detecting the interference beam of the reference and measurement beams.

Abstract: An interferometer and related methods for wavelength monitoring are disclosed. The interferometer may be used for the wavelength monitoring or as part of a wavelength feedback and control circuit for an optical signal source. The device operates by creating an output beam on which constructive and destructive optical interference may be detected. The optical interference is generated by a monochromatic beam split into a first beam traversing a stationary path and a second beam traversing a path of variable length. The first and second beams are then recombined to create constructive/destructive interference which may be measured by a detector and correlated with a processor to determine the output wavelength of the optical source. The maximum and minimum of the variable path length are precisely controlled due to use of a micro-positionable semiconductor retroreflector or mirror.

Abstract: An interferometer for Fourier spectroscopy, wherein the interferometer comprises a beamsplitter (14) and two retroreflectors (20, 26), characterized in that the beamsplitter (14) is mounted movable, e.g., mounted pivotally or displacably, while both retroreflectors (20, 26) are arranged as fixed retroreflectors. The proposed structure is simple to produce, can be made substantially insensible to environmental vibrations, and it is well suited for routine measurements for the determination of quantities of predefined components in a medium. The interferometer is particularly intended for measurements in the mid- or near-infrared range for determination of the quantities of specified components in a medium, and more specifically in a food product, e.g., a liquid such as milk.