Abstract: An optical filter includes a first substrate, a second substrate opposed to the first substrate, a first reflecting film provided to the first substrate, a second reflecting film provided to the second substrate, and opposed to the first reflecting film, a first electrode provided to the first substrate, a second electrode provided to the second substrate, and opposed to the first electrode, and a voltage control section adapted to control an electrical potential difference between the first electrode and a second electrode, and when switching a wavelength of a light beam to be dispersed by switching the electrical potential difference between the first electrode and the second electrode, and measuring an intensity of the light beam dispersed, the voltage control section switches the electrical potential difference from a first electrical potential difference to a second electrical potential difference larger than the first electrical potential difference.

Abstract: A device (100) for converting an acoustic signal (102) into an electric signal (104), wherein the device (100) comprises an interferometer (106) comprising two mirrors (108) adapted for reflecting electromagnetic radiation (112) coupled into a space (110) between the mirrors (108), wherein the acoustic signal (102) is to be coupled into the space (110) for influencing the electromagnetic radiation (112) in accordance with the acoustic signal (102), an electromagnetic radiation detector (112) adapted for detecting the influenced electromagnetic radiation (112) and for converting the detected influenced electromagnetic radiation (112) into the electric signal (104) being indicative for the acoustic signal (102), and an operation point stabilization unit adapted for stabilizing an operation point of the device (100).

Abstract: Light scattered by a portion of a fluid medium illuminated by a beam of substantially monochromatic light is received within a field-of-view nominally along an axis oriented in a different direction relative to the beam and processed by an interferometer to generate a corresponding fringe pattern that is detected and processed to generate at least one measure of the fluid medium at a plurality of different ranges.

Abstract: Systems (200) and methods (300) for measuring geometric changes of a passive material (414) when heat and pressure are applied thereto. The methods involve forming a pad (108, 510) on a passive material panel (410). The pad includes at least one of a layer of a passive material (414) and a layer of a metal (416). The methods also involve coupling an interferometer (810) to the pad. The method also involves forming a multi-layer structure by placing at least one substrate panel (400) on top of the passive material such that an aperture (602) formed in the substrate panel is aligned with the pad. Pressure and heat are applied to the multi-layer structure. Data is collected using the interferometer while the pressure and heat are applied to the multi-layer structure. The interferometer can include, but is not limited to, a Fabry-Perot interferometer, a Michelson interferometer and/or a Mach-Zehnder interferometer.

Abstract: Desired spectral characteristics are attained by making reflection films close enough. A variable spectroscopy device (1) has a pair of optical substrates (2, 3) opposing each other with an interval therebetween, two reflection films (5) opposing each other which are respectively disposed on opposing surfaces of the optical substrates (2, 3), two sensor electrodes (6) opposing each other which are disposed on the same surfaces as the reflection films (5) and which constitute an interval sensor for detecting an interval between the optical substrates (2, 3), and an actuator (4) which relatively moves the optical substrates (2, 3) and changes the interval between the optical substrates (2, 3). A distance between the opposing surfaces of the two sensor electrodes (6) is longer than a distance between the opposing surfaces of the two reflection films (5).

Abstract: An optical transmitter is disclosed having a temperature stabilization system for an optical filter for maintaining constant the frequency response of the filter. The filter is mounted within a housing having a substantially higher thermal conductivity. The housing may include a copper-tungsten alloy and extend along the optical axis of the filter. The housing is in thermal contact with a thermo-electric cooler (TEC) and a temperature sensor. The TEC and temperature sensor are electrically coupled to a controller which adjusts the temperature of the TEC according to the output of the temperature sensor.

Abstract: Optical filters tunable for both center wavelength and bandwidth, having applications such as in astronomy, remote sensing, laser spectroscopy, and other laser-based sensing applications, using Michelson interferometers or Mach-Zehnder interferometers modified with Gires-Tournois interferometers (“GTIs”) are disclosed. A GTI nominally has unity magnitude reflectance as a function of wavelength and has a phase response based on its resonator characteristics. Replacing the end mirrors of a Michelson interferometer or the fold mirrors of a Mach-Zehnder interferometer with GTIs results in both high visibility throughput as well as the ability to tune the phase response characteristics to change the width of the bandpass/notch filters. A range of bandpass/bandreject optical filter modes, including a Fabry-Perot (“FP”) mode, a wideband, low-ripple FP mode, a narrowband notch/bandpass mode, and a wideband notch/bandpass mode, are all tunable and wavelength addressable.

Abstract: A phase-shifting interferometry (PSI) method and corresponding system including: (i) recording an interferogram for each phase in a sequence of phases between test light reflected from a test surface and reference light reflected from a reference surface, the test and reference light being derived from a common source, each interferogram corresponding to an intensity pattern produced by interfering the reflected test light with the reflected reference light, the interferograms defining an interferometry signal for each of different transverse locations of a cavity defined by the test and reference surfaces, each interferometry signal including a series of intensity values corresponding to the sequence of phases, with the difference between each pair of phases in the sequence defining a corresponding phase shift increment; (ii) calculating an initial phase map for the cavity based on at least some of the recorded interferograms; (iii) calculating an estimate for each of at least some of the phase shift increme

Abstract: A pressure measurement system and method are described. The system uses a tunable laser and a Fabry-Perot sensor with integrated transducer. A detector senses the light modulated by the Fabry-Perot sensor. A signal conditioner, which can be located up to 15 km away, then uses the detector signal to determine the displacement of the diaphragm, which is indicative of pressure exerted against the diaphragm. Use of a temperature sensor to generate a signal, fed to the signal conditioner, to compensate for temperature is also contemplated.

Abstract: A device can include both a photosensing component and an optical cavity structure, with the optical cavity structure including a part that can operate as an optical cavity in response to input light, providing laterally varying output light. For example, the optical cavity can be a graded linearly varying filter (LVF) or other inhomogeneous optical cavity, and the photosensing component can have a photosensitive surface that receives its output light without it passing through another optical component, thus avoiding loss of information. The optical cavity part can include a region that can contain analyte. Presence of the analyte affects the optical cavity part's output light, and the photosensing component can respond to the output light, providing sensing results indicating the analyte's optical characteristics.

Abstract: An optical coherence analysis system comprising: a first swept source that generates a first optical signal that is tuned over a first spectral scan band, a second swept source that generates a second optical signal that is tuned over a second spectral scan band, a combiner for combining the first optical signal and the second optical signal for form a combined optical signal, an interferometer for dividing the combined optical signal between a reference arm leading to a reference reflector and a sample arm leading to a sample, and a detector system for detecting an interference signal generated from the combined optical signal from the reference arm and from the sample arm.

Abstract: A color detector includes a light source configured to generate light with a spectrum of wavelengths; a plurality of filters in optical communication with the light source, wherein each filter is configured to pass a bandwidth of wavelengths around a different peak wavelength; and a plurality of photodetectors, each configured to receive light passed through a respective filter of the plurality of filters. The bandwidth of each filter is configured to Correspond to a bandwidth of a curve from a set of standard color matching functions. A method for improving color detection accuracy in a color detector includes matching a bandwidth passed by each of a plurality of color filters with a bandwidth and peak wavelength of a Commission Internationale de l'Eclairage (CIE) color matching function; and separately detecting an amount of light passed by each the filter.

Abstract: Disclosed is a microelectromechanically tunable Fabry-Perot device and method of manufacturing tunable Fabry-Perot device and method of manufacturing. The F-P device comprises a first and second substrate which has partially reflective planar surfaces, and the partially reflective planar surfaces are separated by a predetermined separation distance and aligned to provide a F-P cavity, where one or more piezoelectric members are adapted to displace the first and second substrates when an electric field is applied.

Abstract: An integrated swept wavelength optical source uses a filtered ASE signal with an optical amplifier and tracking filter. This source comprises a micro optical bench, a source for generating broadband light, a first tunable Fabry Perot filter, installed on the bench, for spectrally filtering the broadband light from the broadband source to generate a narrowband tunable signal, an amplifier, installed on the bench, for amplifying the tunable signal, and a second tunable Fabry Perot filter, installed on the bench, for spectrally filtering the amplified tunable signal from the amplifier. A self-tracking arrangement is also possible where a single tunable filter both generates the narrowband signal and spectrally filters the amplified signal. In some examples, two-stage amplification is provided. The use of a single bench implementation yields a low cost high performance system. For example, polarization control between components is no longer necessary.

Abstract: A fiber optic sensor system employs at least one light source that operates to generate light having one or more desired wavelengths. A first optical fiber based sensor transparent to a desired light wavelength operates to sense a magnetic field emitted from a predetermined electrical conductor or a current flowing through the electrical conductor. A temperature sensor that may be another optical fiber based sensor operates to sense an operating temperature associated with the first optical fiber based sensor in response to the light generated by the light source. Signal-processing electronics adjust the sensed current to substantially compensate for temperature induced errors associated with the sensed current in response to the measured operational temperature of the fiber optic sensor.

Abstract: The invention relates to an optical filter and a method for its production, and to a device for the examination of the spectral and spatial distribution of an electromagnetic radiation irradiated from an object. The invention is based on the task of providing an optical filter of the above described type that is inexpensive to produce, which can be used to detect a plurality of wavelengths, in which, however, tuning of the DBR mirrors by means of displacement is not necessary. Furthermore, a method for the production of such a filter is provided.

Abstract: Disclosed herein are methods and apparatus for testing interferometric modulators. The interferometric modulators may be tested by applying a time-varying voltage stimulus and measuring the resulting reflectivity from the modulators.

Abstract: Optical filters tunable for both center wavelength and bandwidth, having applications such as in astronomy, remote sensing, laser spectroscopy, and other laser-based sensing applications, using Michelson interferometers or Mach-Zehnder interferometers modified with Gires-Tournois interferometers (“GTIs”) are disclosed. A GTI nominally has unity magnitude reflectance as a function of wavelength and has a phase response based on its resonator characteristics. Replacing the end mirrors of a Michelson interferometer or the fold minors of a Mach-Zehnder interferometer with GTIs results in both high visibility throughput as well as the ability to tune the phase response characteristics to change the width of the bandpass/notch filters. A range of bandpass/bandreject optical filter modes, including a Fabry-Perot (“FP”) mode, a wideband, low-ripple FP mode, a narrowband notch/bandpass mode, and a wideband notch/bandpass mode, are all tunable and wavelength addressable.

Abstract: A Fabry-Perot interferometer and a manufacturing method of the same are disclosed. The Fabry-Perot interferometer includes a first mirror structure and a second mirror structure opposed to each other with a gap therebetween. A first mirror and a first electrode of the first mirror structure are electrically insulated from each other, or, a second mirror and a second electrode of the second mirror structure are electrically insulated from each other. In a state of voltage application between the first and second electrode, a distance “dmi” between the first mirror and the second mirror is shorter than a distance “dei” between a first-electrode-inclusive-portion and a second-electrode-inclusive-portion.

Abstract: An optical assembly for use in an interferometer is provided. The optical assembly includes first and second partially reflective surfaces positioned along an optical axis and oriented at different non-normal angles to the optical axis. The second partially reflective surface is configured to receive light transmitted through the first partially reflective surface along the optical path, transmit a portion of the received light to a test object to define measurement light for the interferometer and reflect another portion of the received light back towards the first partially reflective surface to define reference light for the interferometer. The reference light makes at least one round trip path between the second and first partially reflective surfaces.

Abstract: A system and method includes a tunable light source and a gas cell configured to detect the presence of gases at terahertz frequencies. The light source is operable to emit a light signal at terahertz frequencies. The gas cell includes at least two high frequency mirrors adapted to reflect signals at terahertz frequencies. The gas cell is adapted to be tuned based on the frequency of the emitted light to obtain a Fabry-Perot resonance of the reflected light signal. A pair of detectors are operable to detect the original light signal and the light signal reflected through absorption paths in the gas cell. The system and method are operable to determine a presence and identity of a gas present in the gas cell.

Abstract: An environmental sensing device includes an interferometric modulator which permanently actuates, in a visually-detectable manner, in response to being exposed to a predetermined environmental threshold or condition. The device can include a reactive layer, coating, or proof mass disposed on a movable member of the interferometric modulator. The reactive layer, coating, or proof mass can expand, contract, bend, or otherwise move when exposed to a predefined chemical, level of humidity, temperature threshold, type of radiation, and/or level of mechanical shock, causing the interferometric modulator to collapse and permanently indicate such exposure.

Abstract: An implantable product includes an optical cavity structure with first and second parts, each of which can operate as an optical cavity. The first part includes a container with at least one opening through which bodily fluid can transfer between the container's interior and exterior when the product is implanted in a body. The second part includes a container that is closed and contains a reference fluid. The implantable product can also include one or both of a light source component and a photosensing component. Photosensed quantities from the first part's output light can be adjusted based on photosensed quantities from the second part's output light. Both parts can have their light interface surfaces aligned so that they both receive input light from a light source component and both provide output light to a photosensing component.

Abstract: An optical tomography imaging a tomogram by using a coherent light by a backscattering light of a measured object and a reflected light of a reference mirror, which has supercontinuum light sources, an optical system having group velocity dispersion connected to the supercontinuum light source, an optical detection element detecting a coherent light by a backscattering light of the measured object and a reflected light of the reference mirror, a timing detection element detecting a timing of each wavelength component in an output light from the optical system having the group velocity dispersion, and a unit sampling a signal from the optical detector by using a timing signal from the timing detection element with a signal from the supercontinuum light source as a trigger, and detecting an optical tomogram signal imaging a tomogram, thereby acquiring an optical tomogram at a higher speed than a conventional SS-OCT.

Abstract: A sensing system using a sensing element being constituted by a transparent body sandwiched by first and second reflectors one or each of which is in contact with a specimen, and exhibiting an absorption characteristic varying with the specimen. The first reflector is a partially transparent reflective, and the second reflector is completely reflective, or partially transparent reflective. A light injection unit injects light onto the first reflector, and a light detection unit detects the intensity of light outputted from the sensing element in response to the injection. The light injection unit has a wavelength stabilizing arrangement and injects laser light, or injects light at two wavelengths. In the latter case, the light detection unit detects the intensities of outputted light at the two wavelengths, and a calculation unit obtains the difference between the intensities.

Abstract: The present invention provides method and system for lateral scanning interferometry (LSI), which utilizes a reflecting reference element having a tilted angle for generating a tilted optical plane formed by wavefronts of a reference light so that interferometric patterns are acquired according to interferometric lights directed through an objective lens or an array of micro objective lens for analysis while the surface parts of the object enters the coherent range formed by the wavefronts of the reference light during lateral movement and a maximum signal intensity with respect to the acquired interferometric patterns can be obtained while the surface profile of the object has a zero or near zero optical path difference (OPD) with respect to the plane of wavefronts. The present invention is capable of reducing time cost comparing to the conventional vertical scanning interferometric method while enabling the system to be utilized for in-line (in-situ) measurement.

Abstract: While objects travel through an optical cavity, the cavity provides output light that is affected by the objects, causing the output light to have a varying intensity function. The output light is photosensed to obtain sensing results that depend on the varying intensity function. The sensing results are used to distinguish at least one object, such as from its environment or from objects of other types. The objects can, for example, be particles or biological cells, and their optical characteristics, such as refractive index or absorption, can affect the output light, so that information about them is included in the output light. The output light can, for example, have a laterally varying intensity function with peaks whose features change due to the objects. The sensing results can also be used to track objects, together with other information, such as about the speed of a fluid that carries the objects through the cavity.

Abstract: An inhomogeneous optical cavity is tuned by changing its shape, such as by changing reflection surface positions to change tilt angle, thickness, or both. Deformable components such as elastomer spacers can be connected so that, when deformed, they change relative positions of structures with light-reflective components such as mirrors, changing cavity shape. Electrodes can cause deformation, such as electrostatically, electromagnetically, or piezoelectrically, and can also be used to measure thicknesses of the cavity. The cavity can be tuned, for example, across a continuous spectrum, to a specific wavelength band, to a shape that increases or decreases the number of modes it has, to a series of transmission ranges each suitable for a respective light source, with a modulation that allows lock-in with photosensing for greater sensitivity, and so forth.

Abstract: A device for performing polarization mode dispersion (PMD) measurements of an optical fiber is disclosed. The PMD measurement device employs a fixed analyzer method, and includes a tunable Fabry-Perot inferometer as the wavelength-selective element and an optical bandpass filter for spectrum calibration. A novel scanning algorithm, which performs multiple scans at different velocities, enables accurate PMD measurements, even of moving optical cable. The tunable Fabry-Perot interferometer is able to scan over a wide wavelength range and yet have a narrow linewidth, such that a wide range of PMD values can be measured.

Abstract: An optical pressure sensor interrogation system is provided. The system includes a light source for providing an optical signal to an optical pressure sensor and an optical coupler for receiving a reflected signal from the optical pressure sensor. The optical coupler splits the reflected signal and provides a first portion of the reflected signal to a first optical detector. The system further includes a filter for receiving a second portion of the reflected signal and providing a filtered signal to a second optical detector and a processing circuitry configured to obtain pressure based on a division or a subtraction of light intensities of the first and the second optical detector output signals.

Abstract: A method for reducing fringe interference of light created in a passive cavity defined by partially reflecting optical surfaces, wherein the optical path length of the cavity is varied with a Gaussian distribution, where the standard deviation is at least one-quarter of the light's wavelength.

Abstract: Methods, systems, apparatus and devices for using a modified PDH technique to measure the FSR of an etalon with one part per 104 precision.

Abstract: A phase-shifting interferometry (PSI) method and corresponding system including: (i) recording an interferogram for each phase in a sequence of phases between test light reflected from a test surface and reference light reflected from a reference surface, the test and reference light being derived from a common source, each interferogram corresponding to an intensity pattern produced by interfering the reflected test light with the reflected reference light, the interferograms defining an interferometry signal for each of different transverse locations of a cavity defined by the test and reference surfaces, each interferometry signal including a series of intensity values corresponding to the sequence of phases, with the difference between each pair of phases in the sequence defining a corresponding phase shift increment; (ii) calculating an initial phase map for the cavity based on at least some of the recorded interferograms; (iii) calculating an estimate for each of at least some of the phase shift increme

Abstract: A phase-shifting interferometry (PSI) method and corresponding system including: (i) recording an interferogram for each phase in a sequence of phases between test light reflected from a test surface and reference light reflected from a reference surface, the test and reference light being derived from a common source, each interferogram corresponding to an intensity pattern produced by interfering the reflected test light with the reflected reference light, the interferograms defining an interferometry signal for each of different transverse locations of a cavity defined by the test and reference surfaces, each interferometry signal including a series of intensity values corresponding to the sequence of phases, with the difference between each pair of phases in the sequence defining a corresponding phase shift increment; (ii) calculating an initial phase map for the cavity based on at least some of the recorded interferograms; (iii) calculating an estimate for each of at least some of the phase shift increme

Abstract: An environmental sensing device includes an interferometric modulator which permanently actuates, in a visually-detectable manner, in response to being exposed to a predetermined environmental threshold or condition. The device can include a reactive layer, coating, or proof mass disposed on a movable member of the interferometric modulator. The reactive layer, coating, or proof mass can expand, contract, bend, or otherwise move when exposed to a predefined chemical, level of humidity, temperature threshold, type of radiation, and/or level of mechanical shock, causing the interferometric modulator to collapse and permanently indicate such exposure.

Abstract: Provided is a method for determining the optimal resonant length, among a large number of local resonant lengths which satisfy a resonant condition, that maximizes wave intensity in a resonant structure. In the second harmonic generation or the cascaded difference frequency generation device using the resonant structure by which the second harmonic wave of a pump wave resonates, the optimal resonant length is determined so that the intensity of an optical wave is maximized. The intensity distribution of the optical wave is defined, according to the resonant feedback condition or the no-resonant feedback condition, as a function of the resonant lengths to determine the optimal resonant length.

Abstract: A method and apparatus for detecting seismic vibrations using a series of MEMS units, with each MEMS unit including an interferometer is described. The interferometers on the MEMS units receive and modulate light from two differing wavelengths by way of a multiplexing scheme involving the use of Bragg gratings and light circulators, and an optoelectronic processor receives and processes the modulated light to discern vibrational movement of the system, which in turn allows for monitoring and calculation of a specified environmental parameter, such as seismic activity, temperature or pressure.

Abstract: A leak detection and identification system a Fabry-Perot etalon, an imaging lens, a microbolometer camera, and a computer for spectral and image data post-processing, wherein the data peaks are deconvoluted for use thus avoiding the need for bandpass filters.

Abstract: Systems and apparatus enhance transmission of electromagnetic energy through a sub-wavelength aperture. A metal film has an input surface and an output surface and forms the sub-wavelength aperture between the input and output surfaces, a first plurality of grooves on the input surface, and a cavity around the sub-wavelength aperture. The width of the cavity determines a resonant wavelength of electromagnetic energy transmitted through the sub-wavelength aperture. The patterned metal film provides plasmon coupling of electromagnetic energy incident upon the input surface transmit electromagnetic energy through the sub-wavelength aperture.

Abstract: An apparatus and method for analyzing biological cells and other particles using an external laser cavity. Microfluidic channels contain and transport biological cells to be analyzed. A laser diode provides light for cell analysis. An external cavity is provided between one surface of the laser diode and a mirror opposite thereto. A microlens set focuses the light on only one cell as it passes through the external cavity. The presence of the cell in the external cavity gives a weak feedback toward the laser diode. The emission frequency and the output power of the laser are both functions of the length of the external cavity. Therefore, the variation of cavity length can be deduced from these parameters, where the variation is caused by changing the refractive index or size of the cell in the cavity.

Abstract: A spectrum sensing method includes (a) receiving an incident radiation simultaneously through a filter array composed of multiple bandpass filters, (b) digitizing spectral responses of the filter array, and (c) generating an estimate of spectral profile of the incident radiation based on digitized spectral responses of the filter array.

Abstract: The invention relates to a device (10) for determining absorption of a sample, comprising an incoherent radiation source (12) for generating a measuring light beam (20), a resonator that is provided with at least two mirrors (30, 32) into which the measuring light beam can be coupled, a sample volume (38) for receiving an absorbing sample within the resonator (14), and a detector (18) for absorbing the radiation that can be decoupled from the resonator (14). The inventive device (10) includes spectrometric or interferometric means (16), provided between the radiation source (12) and the detector (18), for spectrally splitting the measuring light beam. Means may also be provided for generating a signal that represents the amplitude of the measuring light beam independently of the phase.

Abstract: A semiconductor optical element has an active layer including quantum dots. The density of quantum dots in the resonator direction in a portion of the active layer in which the density of photons is relatively high is increased relative to the density of quantum dots in a portion of the active layer in which the density of photons is relatively low.

Abstract: An apparatus characterizes at least one fiber Bragg grating. The apparatus includes a laser pulse source, an optical spectrum analyzer, and multiple optical paths. A first optical path includes a pulse stretcher and an attenuator. A second optical path optically coupled to the first optical path includes a mirror. A third optical path optically coupled to the first optical path includes a first fiber Bragg grating. A fourth optical path is optically coupled to the second optical path, the third optical path, and the optical spectrum analyzer. A fifth optical path optically coupled to the laser pulse source and the optical spectrum analyzer includes a delay line.

Abstract: A method and apparatus for estimating bandwidth of laser output light is described which may include a dispersive element producing a dispersed output having a plurality of spectrum images from at least a portion of the laser output light. An array of light detecting elements is oriented to receive the dispersed output together with a shifting mechanism that moves the array, the dispersed output, or both, relative to each other. Electronics may be provided for determining the widths of at least two spectrum images at different phases of registration between the spectrum images and light detector elements and for averaging the widths to estimate a laser output bandwidth. The-spectrum images formed by the laser output light may be under-sampled, e.g., in the spatial or time domains.

Abstract: An optical multilayer mirror of a Fabry-Perot interferometer includes a reinforcing section provided as a side wall of each of second and fourth high refractive-index layers. The reinforcing section is configured to support a portion of each of the second and fourth high refractive-index layers covering a top surface of each of first and second low refractive-index layers and reach first and third high refractive-index layers via each of the first and second low refractive-index layers, respectively. Even when the first and second low refractive-index layers lack a mechanical strength with a high n ratio achieved by selecting materials for the first through fourth high refractive-index layers and the first and second low refractive-index layers, the reinforcing section helps prevent the second and fourth high refractive-index layers from being bent. The optical multilayer mirror thus features a wide high-reflectance band.

Abstract: An optical sensing probe includes a tube having a tip portion configured for placement in an environment in which conditions are to be sensed and an etalon having a known characteristic disposed proximate the tip portion. The tube also includes a head portion remote from the tip portion containing a light directing element for directing light beams at the etalon and receiving reflected light beams from the etalon wherein the received reflected light beams are used for determining an environmental condition proximate the tip portion. A method for measuring a thickness of the etalon may include directing a light beams at different frequencies at the etalon and receiving the light beams from the etalon. The method may also include identifying conditions of the respective light beams condition received from the etalon and then calculating a first thickness of the etalon responsive to the respective conditions and the known characteristic.

Abstract: A system and method includes a tunable light source and a gas cell configured to detect the presence of gases at terahertz frequencies. The light source is operable to emit a light signal at terahertz frequencies. The gas cell includes at least two high frequency mirrors adapted to reflect signals at terahertz frequencies. The gas cell is adapted to be tuned based on the frequency of the emitted light to obtain a Fabry-Perot resonance of the reflected light signal. A pair of detectors are operable to detect the original light signal and the light signal reflected through absorption paths in the gas cell. The system and method are operable to determine a presence and identity of a gas present in the gas cell.

Abstract: A wavelength of an optical source is monitored by first and second adjacent detectors on a common base. A bulk reflective component has first and second partially reflective surfaces that respectively direct first and second portions of energy from the source to the first and second detectors. A wavelength discriminator is positioned between the first detector and first surface. An optical isolator downstream of the reflective component prevents radiation from the source and exiting the component from being coupled to the detectors and back to the source.

Abstract: A gas concentration measuring apparatus is in miniaturized form and permits the measurement of anesthetic gas components. A variable interferometer is provided on the basis of a Fabry Perot interferometer (1) wherein the mirrors (2, 3) can be changed in spacing with respect to each other. The mirrors (2, 3) have coatings which make possible the transmission in two spectral ranges (??1, ??2).