Abstract: In one embodiment, a lidar system includes a light source configured to emit (i) local-oscillator light and (ii) pulses of light, where each emitted pulse of light is coherent with a corresponding portion of the local-oscillator light. The lidar system also includes a receiver configured to detect the local-oscillator light and a received pulse of light, the received pulse of light including light from one of the emitted pulses of light that is scattered by a target located a distance from the lidar system. The local-oscillator light and the received pulse of light are coherently mixed together at the receiver. The lidar system further includes a processor configured to determine the distance to the target based at least in part on a time-of-arrival for the received pulse of light.

Abstract: In a Fourier-transform spectroscopy apparatus, a scanning mirror is arranged on a light path of scanning light. The scanning mirror delays or advances the scanning light with respect to reference light according to the rotational angle of the scanning mirror from its initial position. A spectroscopic spectrum generating unit generates an interferogram based on the intensity of the detection target light obtained from the detection target, and Fourier transforms the interferogram thus generated. The spectroscopic spectrum generating unit corrects the nonlinearity of the group delay between an envelope of the reference light and an envelope of the scanning light, and corrects the nonlinearity of the phase shift between the respective envelopes.

Abstract: An optical beam controller includes: an optical multiple-beam generator generating a plurality of wavelength-swept optical beams; and an optical frequency difference setter setting an optical frequency difference in any combination of the plurality of optical beams in such a way as to be larger than a band of a photodetector that receives an optical beam.

Abstract: A method for full-field measurement using Doppler imaging, comprising the following steps: turning on a laser and adjusting the laser; adjusting a spatial filter to obtain circular laser spots having uniform intensity distribution; adjusting a quarter-wave plate and a whole polarizer in a system, and requiring two beams in a reference object and a measured object having different frequencies and perpendicular polarization directions; applying slight pressure to the measured object, setting a charge coupled device (CCD) camera into a continuous acquisition mode, observing interference fringes, and adjusting a light path so that the fringes are clear and visible; setting the sampling frequency, sampling time, captured image format and resolution size of the CCD camera; turning on a lithium niobate crystal drive power switch to produce a heterodyne carrier frequency; applying continuous equal pushing force to the measured object by means of piezoelectric ceramics (PZT) so as to make the measured object produce c

Abstract: To optimize an imaging range in a depth direction in terms of a relationship with a resolution, an OCT apparatus includes a signal processor that determines a reflected light intensity distribution of an imaging object on the basis of a spectrum of a detected interference light. The signal processor performs spectrum conversion, having a conversion characteristic with which a light source spectrum is converted to a Gaussian distribution curve, on the spectrum of the interference light, and determines the reflected light intensity distribution by Fourier-transforming a spectrum resulting from the spectrum conversion. In the conversion characteristic, the light source spectrum and the Gaussian distribution curve have center wavelengths differing from each other.

Abstract: A 3-D imaging system including a computer determining a plurality of coherence factors measuring an intensity contrast between a first intensity of a first region of an interference comprising constructive interference between a sample wavefront and a reference wavefront, and a second intensity of a second region of the interference comprising destructive interference between the sample wavefront and the reference wavefront, wherein the interference between a reference wavefront and a reflection from different locations on a surface of an object. From the coherence factors, the computer determines height data comprising heights of the surface with respect to an x-y plane perpendicular to the heights and as a function of the locations in the x-y plane. The height data is useful for generating a three dimensional topological image of the surface.

Abstract: Noise in cavity enhanced spectroscopy due to higher order mode excitation in a resonant cavity is reduced. There are two main points. The first point is that the source and detector are both fiber coupled, to provide the spatial filtering and other general advantages of fiber coupling. The second point is that the cavity is designed to ensure sufficient separation in frequency between the desired TEM00 mode and the first few higher order spatial modes.

Abstract: A method is presented for determining path length fluctuations in an interferometer using a reference laser with an arbitrary frequency with respect to the measured light. The method includes: injecting reference light along signal paths of the interferometer; measuring interference between the reference light at an output of the interferometer; determining an optical phase difference between the reference light in the two signal paths of the interferometer by measuring intensity modulation of the interference between the reference light and subtracting an intended frequency modulation from the measured intensity modulation; accumulating an unwrapped phase difference between the reference light in the two signal paths of the interferometer, where the unwrapped phase difference is defined in relation to a reference; and determining path length fluctuation of light in the interferometer using the unwrapped phase difference.

Abstract: A sensor system includes a self-mixing interferometry sensor; a drive circuit configured to apply a modulated drive signal to an input of the self-mixing interferometry sensor; a mixer circuit configured to mix a modulated output of the self-mixing interferometry sensor with a local oscillator signal that is orthogonal to the modulated drive signal over a period of time; an integrator circuit configured to integrate an output of the mixer circuit over the period of time; and a processor configured to determine, using an output of the integrator circuit, at least one of a round-trip propagation time of electromagnetic radiation emitted by the self-mixing interferometry sensor and reflected back into the self-mixing interferometry sensor by an object or medium, or a velocity of the object or medium.

Abstract: A detector comprises an optical parametric oscillator having a non-linear material adapted to convert via a parametric process pump light into down converted light of two different wavelengths, the first wavelength being longer than the second wavelength. The non-linear material is provided in a down converted wave cavity arranged to resonate only one of the first or second wavelengths. The detector comprises means for modulating light in the down converted wave cavity to induce an acoustic or pressure wave caused by absorption of the resonant one of the first and second wavelengths. The detector further comprises means located in the down-converted wave cavity for detecting the acoustic or pressure wave. The detector may be used for detecting or sensing very low levels of a fluid, for example a gas such as ethane.

Abstract: Disclosed herein are electronic devices having touch input surfaces. A user's touch input or press on the touch input surface is detected using a set of lasers, such as vertical-cavity surface-emitting lasers (VCSELs) that emit beams of light toward the touch input surface. The user's touch causes changes in the self-mixing interference within the VCSEL of the emitted light with reflected light, such as from the touch input surface. Deflection and movement (e.g., drag motion) of the user's touch is determined from detected changes in the VCSELs' operation due to the self-mixing interference.

Abstract: In one aspect, a computer-implemented method is disclosed. The computer-implemented method may include determining a sketch matrix that approximates a matrix representative of a reference dataset. The reference dataset may include at least one computer program having a predetermined classification. A reduced dimension representation of the reference dataset may be generated based at least on the sketch matrix. The reduced dimension representation may have a fewer quantity of features than the reference dataset. A target computer program may be classified based on the reduced dimension representation. The target computer program may be classified to determine whether the target computer program is malicious. Related systems and articles of manufacture, including computer program products, are also disclosed.

Abstract: A free-space optical communication method is provided. An example method may include generating an optical frequency comb comprising a first tone and a second tone different from the first tone. The method may include modulating, by a first modulator of a first device, the first tone to generate a first signal comprising data. The method may include modulating, by a second modulator of the first device, the second tone to generate a second signal that is a phase conjugate of the first signal. The method may include transmitting, via free-space and to a second device, a communication signal having the first signal and the second signal.

Abstract: The present invention relates to communication systems, devices, and methods for providing for a wide bandwidth optical receiver including amplification through optical beating from a local oscillator laser operating without a phase-locked loop at frequency near the receiver optical signal and decreasing the system-performances dependence on optical polarization alignment between the signal and the local oscillator. Systems, devices, and methods including a local oscillator providing a local oscillator signal having a local oscillator frequency that may be controlled based on a frequency offset from the signal center frequency through the use of monitoring signals representative of the frequency offset. A combiner/splitter couples the optical data signal with light from the local oscillator to provide first and second coupled optical signals with orthogonal polarization. Two opto-electrical converters for converting first and second coupled signals into first and second electrical signals.

Abstract: A method for full-field measurement using Doppler imaging, comprising the following steps: turning on a laser and adjusting the laser; adjusting a spatial filter to obtain circular laser spots having uniform intensity distribution; adjusting a quarter-wave plate and a whole polarizer in a system, and requiring two beams in a reference object and a measured object having different frequencies and perpendicular polarization directions; applying slight pressure to the measured object, setting a charge coupled device (CCD) camera into a continuous acquisition mode, observing interference fringes, and adjusting a light path so that the fringes are clear and visible; setting the sampling frequency, sampling time, captured image format and resolution size of the CCD camera; turning on a lithium niobate crystal drive power switch to produce a heterodyne carrier frequency; applying continuous equal pushing force to the measured object by means of piezoelectric ceramics (PZT) so as to make the measured object produce c

Abstract: Aspects of the present disclosure describe systems, methods, and structures that provide eye-tracking by 1) steering a beam of light through the effect of a microelectromechanical system (MEMS) operating at a resonant frequency onto a corneal surface; and 2) detecting the light reflected from the corneal surface.

Abstract: A method and an apparatus for analyzing a component of an object are provided. The apparatus includes an image sensor including an optical module, and the optical module includes a light source configured to emit a source light, a first detector configured to detect a first light that is scattered or reflected from the object on which the emitted source light is incident, and a second detector configured to detect a second light that is emitted by the light source but is not incident on the object. The apparatus further includes a processor configured to calculate a scattering coefficient and an absorption coefficient, based on the detected first light and the detected second light, and analyze the component of the object, based on the calculated scattering coefficient and the calculated absorption coefficient.

Abstract: A heterodyne starring array active imager for producing an image. The imager comprises a light source and a component for segregating the light into frequency bands, each band intermittently illuminating a region of a scene and an array of light collecting sites, each comprising: a coupling component optically coupling scene light into a first waveguide and a local oscillator light coupled into a second waveguide. First and second waveguides coupled to a third waveguide with scene light and local oscillator light propagating into the third waveguide. A square law photo detector at each light collecting site receives the merged light for heterodyning the scene light and the local oscillator light. Components receive and process the heterodyned light from the photo detectors to produce a frame signal for each light collecting site. A read-out device produces an array signal responsive to the frame signal from each light collecting site.

Abstract: A method of forming a device includes emitting a coherent light beam and providing a mask including a region transparent to the light beam. The method further includes projecting the light beam on a photosensitive layer through the transparent region of the mask. The method further includes forming a recess in the photosensitive layer, wherein the recess corresponds to a position of the transparent region of the mask. The method further includes filling an organic light emitting material in the recess.

Abstract: A device for measuring surface-temperature of a turbine blade, the device including a probe having a front-end mirror for receiving infrared radiation of a surface on the blade, a collimation lens for refracted the infrared radiation, a PD detector to receive the infrared radiation, and a focal-length servo; and a radial-scanning servo connected to the probe. The front-end mirror, the collimation lens, and PD detector are disposed along the optical axis of the collimation lens. The focal-length servo is adapted to move the collimation lens along the optical axis of the collimation lens. The radial-scanning servo is adapted to move the probe along the optical axis of the collimation lens. The device of the invention is capable of accurately targeting a particular point on the blade having an irregular shape for temperature measurement to accurately detect the temperature distribution on the surface of the blade.

Abstract: A free-space optical communication method is provided. The method includes generating, at a transmitter of a satellite, an optical frequency comb and a pump signal, modulating the optical frequency comb to generate a data signal and an idler signal that is a phase conjugate of the data signal, attenuating the pump signal, transmitting over free-space, from the satellite, a communication signal having the data signal, the idler signal and the pump signal, receiving from the satellite, at a receiver, the transmitted communication signal having the data signal, the idler signal, and the attenuated pump signal, amplifying, at a phase-sensitive amplifier, the data signal and the idler signal, and demodulating the data signal and the idler signal to extract data.

Abstract: The present invention relates to communication systems, devices, and methods for providing for a wide bandwidth optical receiver including amplification through optical beating from a local oscillator laser operating without a phase-locked loop at frequency near the receiver optical signal and decreasing the system-performances dependence on optical polarization alignment between the signal and the local oscillator. Systems, devices, and methods including a local oscillator providing a local oscillator signal having a local oscillator frequency that may be controlled based on a frequency offset from the signal center frequency through the use of monitoring signals representative of the frequency offset. A combiner/splitter couples the optical data signal with light from the local oscillator to provide first and second coupled optical signals with orthogonal polarization. Two opto-electrical converters for converting first and second coupled signals into first and second electrical signals.

Abstract: The invention relates to an optical sensor system, which is designed to interact with a mobile computer device, which has at least one light source and at least one camera, wherein the sensor system has at least one incoupling interface for coupling light from the light source of the computer device into the sensor system and at least one outcoupling interface for coupling light from the sensor system out to the camera of the computer device, wherein the sensor system has at least one optical light-guiding path, by means of which the outcoupling interface is optically connected to the incoupling interface, wherein at least one sensor designed to modify the light guided by the light-guiding path according to a physical quantity influencing the sensor system from outside is arranged in the light-guiding path, wherein at least one sensor designed to modify the light guided by the light-guiding path according to an influencing quantity influencing the sensor system from outside is arranged in the light-guiding pa

Abstract: A heterodyne starring array active imager for producing an image. The imager comprises a light source intermittently illuminating a scene and an array of light collecting sites imaging the scene, each one comprising: a coupling component optically coupling scene light into a first waveguide and a local oscillator light coupled into a second waveguide. The first and second waveguides coupled to a third waveguide such that the scene light and local oscillator light propagate into the third waveguide. A square law photo detector associated with each light collecting site receives the merged light for heterodyning the scene light and the local oscillator light. Components receive and process the heterodyned light from the photo detectors to produce a frame signal for each light collecting site. A read-out device produces an array signal responsive to the frame signal from each light collecting site.

Abstract: A polarimeter for measuring a polarization rotation caused by a measurement object is provided, the polarimeter including an optically active material. The polarimeter includes a light source unit for irradiating a measurement object with light having a specific polarization; an anisotropic meta surface element for splitting reaction light, obtained by reacting the light of the specific polarization irradiated by the light source unit with the measurement object, into first and second reaction light; and a detection unit for detecting the first and second reaction light separated by the anisotropic meta surface element according to polarization. The polarization rotation caused by the measurement object may be calculated by comparing detection signals of the first and second reaction light detected by the detection unit.

Abstract: The present invention relates generally to surgical lasers and more specifically to a laser beam control and delivery system that accurately and efficiently directs a laser beam into an optical fiber. The laser beam control and delivery system also provides additional functions, including a connection for a fiber tip temperature control system and a tissue temperature sensing system. The present invention also relates to a surgical laser system that has a high efficiency thermoelectric cooling system.

Abstract: A distributed fiber optic acoustic detection device employs a novel distributed acoustic detection method using a phase noise cancelling distributed acoustic sensing (PNC-DAS) technique.

Abstract: A coherent optical receiver device includes a first unit configured to output local oscillation light having a predetermined wavelength, a second unit configured to receive an optical signal to have been inputted by making the optical signal interfere with the local oscillation light, a third unit configured to process electrically the optical signal received by the second unit, a fourth unit configured to monitor at least a part of power of the optical signal, and a fifth unit configured to control power of the local oscillation light output by the first unit depending on an optical power monitored by the fourth unit.

Abstract: Provided is an endoscope including a hand piece held by a hand and a main body connected to the hand piece. The hand piece may include a high-strength bar having an optical path providing unit formed therein, the main body may include: a light source unit for providing light; and a light processing unit for processing light, and the light processing unit may include: a beam splitter for splitting the light of the light source unit into a first beam serving as a reference beam and a second beam serving as a sample beam; and a scanner provided at the rear of the beam splitter so as to vary the angle of the second beam.

Abstract: A method in which a gas property (Q) is determined by correlation from physical measuring quantities (?j) of the gas mixtures. In the method, the physical measuring quantities are combined into a sensor output (Sout) by making use of a sensor output function (ƒ), wherein the sensor output function is determined in such a way that a group of gas mixtures can be separated from a set of gas mixtures for which the gas property (Q) is determined, within which the correlation between the sensor output (Sout) and the desired gas property (Q) is better than in the entire set.

Abstract: A method for detecting a crack in a structural component includes receiving, with a processor, signals indicative of at least one image for a critical location in the structural component; determining, with the processor, at least one shape in the at least one image, the at least one shape being representative of a structure of the critical location; representing, with the processor, at least one region around the structure into a matrix; and applying, with the processor, image processing on the matrix to detect cracks in the at least one region of the structural component.

Abstract: The present invention relates to communication systems, devices, and methods for providing for a wide bandwidth optical receiver including amplification through optical beating from a local oscillator laser operating without a phase-locked loop at frequency near the receiver optical signal and decreasing the system-performances dependence on optical polarization alignment between the signal and the local oscillator. Systems, devices, and methods including a local oscillator providing a local oscillator signal having a local oscillator frequency that may be controlled based on a frequency offset from the signal center frequency through the use of monitoring signals representative of the frequency offset. A combiner/splitter couples the optical data signal with light from the local oscillator to provide first and second coupled optical signals with orthogonal polarization. Two opto-electrical converters for converting first and second coupled signals into first and second electrical signals.

Abstract: A system for tracking eye location is disclosed. Systems in accordance with the present invention include a scanner for sweeping a first optical signal across the surface of an eye, a detector for detecting a second optical signal reflected from the eye, and a detection circuit for determining a maximum intensity in the second optical signal. In operation, the scanner sweeps the first optical signal over the surface of the eye while the detection circuitry determines a plurality of intensity maxima in the second optical signal. The time between the intensity maxima during the sweep is indicative of the location of the cornea within the eye surface.

Abstract: A system for type-2 ghost imaging of an object located in or obstructed by a turbulent air section includes a thermal light source, a beamsplitter configured to split light from the thermal light source into two optical paths of substantially equal length, a surface divided into two regions of equal area, a first region including the object and a second region that does not include the object, a narrowband spectral filter, and at least one detector having a predetermined spatial resolution and a predetermined temporal resolution. The object is located on one side of the turbulent air section and the at least one detector is located on another side of the turbulent air section. The at least one detector may be a large area picosecond photo-detector (LAPPD) having a spatial resolution of the order of millimeters and a temporal resolution of the order of 10 to 100 picoseconds.

Abstract: Systems, apparatuses, and methods of classifying flying insects. The methods utilize recording the wingbeat frequency and amplitude spectrum of flying insects and comparing them to known or created insect models to properly classify the flying insect. The error rate of the classification is reduced by utilizing multiple inputs to the classification system, which may include a precise circadian rhythm for the time of year, current environmental conditions, and flight velocity or direction.

Abstract: Disclosed herein is a circuit for determining failure of a movable MEMS mirror. The circuit includes an integrator receiving an opening angle signal representing an opening angle of the movable MEMS mirror, and a differentiator receiving the opening angle signal. A summing circuit is configured to sum the integrator output and the differentiator output. A comparison circuit is configured to determine whether the sum of the integrator output and differentiator output is not within a threshold window. An indicator circuit is configured to generate an indicator signal indicating that the movable MEMS mirror has failed based on the comparison circuit indicating that the sum of the integrator output and differentiator output is not within the threshold window.

Abstract: A system and method involve receiving a sequence of images of an object with at least two consecutive images of the sequence being spatially shifted relative to each other. Each image is transformed into a Fourier domain using a Fourier transform to generate a corresponding plurality of Fourier transformed images. An amplitude filtered pattern is calculated in the Fourier domain based on amplitude components of the plurality of Fourier transformed images. Spatial shifts for pairs of consecutive images in the sequence of images are determined using the amplitude filtered pattern. Images in the sequence of images are aligned based on the determined spatial shifts and the aligned images are summed to form an image-shift-corrected summed image.

Abstract: Methods and apparatuses for the removal, analysis and/or detection of harmful airborne molecular contaminants (AMCs). In one embodiment, an ionizing radiation source is utilized to remove the harmful AMCs from a flow stream via radiolytic particle generation and subsequent capture by filtration. The captured particles may be released, for example, by re-gasification for analysis at much higher concentrations. In another embodiment, the ionizing radiation source is utilized with a particle detector to sense when harmful AMCs are present. In one embodiment, a solid optical medium is exposed to a monitored environment so that the AMCs are in contact with a surface of the solid optical medium. A focused light beam is arranged to emerge from a solid optical medium at an energy density sufficient to cause the AMCs to form deposits on the exposed surface of the solid optical medium, which can be detected using an interferometric technique.

Abstract: To measure the frequency of a laser, the frequency of a beat signal that is generated by the interference between an optical frequency comb, used as the reference of measurement, and the laser to be measured is measured. In such a laser frequency measurement using the optical frequency comb, at least one of a repetition frequency and a CEO frequency of the optical frequency comb is changed so that the frequency of the beat signal becomes a predetermined value, and the frequency of the beat signal is measured, so that the frequency of the laser is measured. This allows measurement of the frequency of laser having large frequency variation and low stability.

Abstract: An optical oscillator 10 combines optical signals L1? and L2 to generate an optical signal L3. The optical signal L1? includes light waves W1? and W2? having frequencies spaced apart by a frequency difference ?f1. The optical signal L2 includes light waves W3 and W4 having frequencies spaced apart by a frequency difference ?f2. The optical oscillator 10 separates the optical signal L3 into optical signals L4 and L5, wherein the optical signal L4 includes the light waves W1? and W3 and the optical signal L5 includes the light waves W2? and W4. The optical oscillator 10 compares the frequency differences ?f1 and ?f2 based on frequency difference ?f3 between the light waves W1? and W3 included in the optical signal L4 and frequency difference ?f4 between the light waves W2? and W4 included in the optical signal L5.

Abstract: An inspection apparatus (300) includes a focus monitoring arrangement (500, 500?). Focusing radiation (505) comprises radiation having a first wavelength and radiation having a second wavelength. Reference radiation and focusing radiation at each wavelength are provided with at least one relative frequency shift so that the interfering radiation detected in the detection system includes a time-varying component having a characteristic frequency. A focus detection system (520) comprises one or more lock-in detectors (520b, 520c, 900). Operating the lock-in detectors with reference to both the first and second characteristic frequencies allows the arrangement to select which of the first and second focusing radiation is used to determine whether the optical system is in focus. Good quality signals can be obtained from targets of different structure.

Abstract: Recording, manipulating, distributing and creating sound pressure waves in one or more media by employing an apparatus that transfers the energy between photons and particles of the media is disclosed. An exemplary apparatus comprises one or more lasers and an isotropic or anisotropic medium for photon processing and distribution. An exemplary method comprises determining the target locations for sound pressure wave recording, manipulating or creation; transmitting photons to the target locations; transferring photon energy to media particles to create or manipulate a sound pressure wave; or transferring energy of media particles to photons for recording or manipulating a sound pressure wave.

Abstract: Systems and methods for measuring the isotope ratio of one or more trace gases and/or components of gas mixtures such as different gas species present in a gas mixture. The system includes a resonant optical cavity having two or more mirrors and containing a gas, the cavity having a free spectral range that equals the difference between frequencies of two measured absorption lines of different gas species in the gas, or of two different isotopes, divided onto an integer number. The system also includes a continuous-wave tunable laser optically coupled with the resonant optical cavity, and a detector system for measuring an absorption of laser light by the gas in the cavity. The detector system includes one of a photo-detector configured to measure an intensity of the intra-cavity light or both a photo-acoustic sensor configured to measure photo-acoustic waves generated in the cavity and a photo-detector configured to measure an intensity of the intra-cavity light.

Abstract: Illustrative embodiments of determining geometric characteristics of reflective surfaces are disclosed. In at least one illustrative embodiment, a method of determining geometric characteristics of reflective surfaces includes sensing electromagnetic waves with a sensor, where the electromagnetic waves have been reflected off a reflective surface of a specimen from a target structure including a feature point. The method further includes determining a displacement of the feature point of the target structure indicated by the sensed electromagnetic waves relative to reference data indicating a reference location for the feature point and determining a surface slope of a point of the reflective surface based on the determined displacement of the feature point of the target structure.

Abstract: Apparatus, systems, and methods of operating a fiber laser having polarization-preserving fibers can be applied as a sensor to detect a physical quantity. In various embodiments, polarization-preserving fibers can provide a laser cavity having an interferometer disposed in the laser cavity. In various embodiments, a fiber optical parametric oscillator can include an interferometer disposed in the cavity of the optical parametric oscillator. Additional apparatus, systems, and methods are disclosed.

Abstract: A reconfigurable photonic integrated circuit focal plane array (RPIC-FPA) includes detectors and photonic integrated circuit coupled to the detectors that are configured to mix a return signal beam with local oscillator (LO) beams to produce a combined beam and direct the combined beam to the detectors. The LO beams have reconfigurable optical properties enabled by the RTIC-FPA. The LO beams are individually addressed to switch the detectors between a direct detection mode and various coherent detection modes based on adjustments to the optical properties of the LO beams. In the coherent detection mode, the controller is configured to mix the return signal beam with the LO beam having adjusted optical properties to produce the combined beam, and, in the direct detection mode, the controller is configured to disable the LO beams based on adjustments to the optical properties and to direct the return signal beam to the detectors without mixing.

Abstract: Systems and methods for measuring the isotope ratio of one or more trace gases and/or components of gas mixtures such as different gas species present in a gas mixture. The system includes a resonant optical cavity having two or more mirrors and containing a gas, the cavity having a free spectral range that equals the difference between frequencies of two measured absorption lines of different gas species in the gas, or of two different isotopes, divided onto an integer number. The system also includes a continuous-wave tunable laser optically coupled with the resonant optical cavity, and a detector system for measuring an absorption of laser light by the gas in the cavity. The detector system includes one of a photo-detector configured to measure an intensity of the intra-cavity light or both a photo-acoustic sensor configured to measure photo-acoustic waves generated in the cavity and a photo-detector configured to measure an intensity of the intra-cavity light.

Abstract: A dynamic phase acquisition device includes a light collecting opening, a semi-reflecting and semi-transmitting mirror, a phase shifter, a polarizer, a plane reflector, a photosensing element and a phase processor. In the dynamic phase acquisition device, light passes through the light collecting opening to the semi-reflecting and semi-transmitting mirror, and then is divided into two channels. One channel of the light sequentially passes through the phase shifter, the polarizer to the photosensing element, to form a first image; the other channel of the light, after being reflected by the plane reflector, directly passes through the polarizer to the photosensing element, to form a second image. The photosensing element sends the first image and the second image to the phase processor, and the phase processor obtains phase data; and a leading or lagging phase shift range of the phase shifter is 1 degree to 20 degrees.

Abstract: A refractive index distribution measuring method includes dividing light emitted from a light source into reference light and test light, causing the reference light to interfere with the test light, which test light has passed through a test object, measuring a phase difference between the reference light and the test light for each of first and second wavelengths, and measuring a wavefront aberration of the test light for each of the first and second wavelengths. The refractive index distribution measuring method further includes calculating a phase-difference difference amount, which is a difference between the phase differences for the first wavelength and the second wavelength, calculating a wavefront aberration difference amount, which is a difference between the wavefront aberrations for the first wavelength and the second wavelength, and calculating a refractive index distribution of the test object based on the phase-difference difference amount and the wavefront aberration difference amount.

Abstract: A gyroscope including a dielectric resonator, a laser vibrometer on a first side of the dielectric resonator, and a laser dump for redirecting or absorbing light received at the laser dump from the laser vibrometer, the laser dump on a second side of the dielectric resonator. A first distance between the dielectric resonator and the laser vibrometer ranges from 10 nm to 20 ?m, and a second distance between the dielectric resonator and the laser dump ranges from 10 nm to 20 ?m.