Abstract: Raman spectroscopy data is collected using a Spatial Heterodyne Spectrometer and processed in order to reduce signal noise. The processing of the Raman spectroscopy data includes segmenting generating an interferogram from the Raman spectroscopy data, segmenting the interferogram, determining an estimate of power spectrum density, and averaging the estimates of power spectrum density for each segment to provide an output spectrum. The output spectrum has greatly reduced variance of the individual power measurements, and allows the length of segments to be optimized to balance noise reduction operations and the loss of frequency resolution.

Abstract: A measuring apparatus includes: a light source device that projects light or light of which intensity is periodically modulated onto a measurement object; a light receiver that receives backscattered light of light projected by the light source device from the measurement object; and a processor comprising hardware, the processor being configured to: measure TOF information of the light projected by the light source device and the backscattered light received by the light receiver; acquire distances from a surface of the measurement object to the light source device and the light receiver; and calculate an internal propagation distance in the measurement object according to the measured TOF information and the acquired distances.

Abstract: There is provided a test method and system for characterizing an optical fiber link. At least one OTDR acquisition or at least one OLTS acquisition is performed on the optical fiber link. From the acquisition, a value of an excess insertion loss and/or an excess optical return loss associated with the optical fiber link under test is derived, i.e. in excess of a nominal value associated with a hypothetical optical fiber link having a length corresponding to the total length of the optical fiber link under test. A rating value (e.g., as a five-star rating) or a binary pass/fail value associated with the optical fiber link under test can then be derived and displayed.

Abstract: A measurement method for a vertical cavity surface emitting laser diode (VCSEL) and an epitaxial wafer test fixture are provided, especially the Fabry-Perot Etalon of the bottom-emitting VCSEL can be measured. When the Fabry-Perot Etalon of the bottom-emitting VCSEL is measured by a measurement apparatus, a light of the test light source of the measurement apparatus is incident from the substrate surface of the VCSEL epitaxial wafer such that the Fabry-Perot Etalon of the bottom-emitting VCSEL is acquired. Through the VCSEL epitaxial wafer test fixture, the bottom-emitting VCSEL can be directly measured by the existing measurement apparatus such that there is no need to change the optical design of the measurement apparatus, and it can prevent the VCSEL epitaxial wafer from being scratched or contaminated.

Abstract: A method for determining a retardance of a layer of a sample. The method includes: transmitting a first portion of a polarized light to a sample arm of an optical system and a second portion of the polarized light to a reference arm of the optical system; combining first return light returned from the sample arm and second return light from the reference arm; detecting, using a detector, the combined light along a first polarization state and a second polarization state to produce polarization data, the second polarization state being different from the first polarization state; determining, using a processor coupled to the detector, polarization states of light returning from upper and lower surfaces of a layer of the sample based on detecting the combined light; and determining, using the processor, a retardance of the layer of the sample based on the determined polarization states.

Abstract: A position encoder for monitoring relative movement between a first object and a second object includes a grating that is coupled to the first object, and an image sensor assembly that is coupled to the second object. The image sensor includes a first image sensor; a second image sensor that is spaced apart from the first image sensor; an optical element that includes a first optical surface and a second optical surface that is spaced apart from the first optical surface; and an illumination system.

Abstract: An acousto-optic modulator (AOM) laser frequency shifter system includes a laser configured to generate an incident beam, a first optical splitter optically coupled to the laser and configured to split the incident beam into at least one portion of the incident beam, at least one phase-shift channel optically coupled to the first optical splitter and configured to generate at least one frequency-shifted beam with an acousto-optic modulator (AOM) from the at least one portion of the incident beam received from the first optical splitter, and a second optical splitter configured to receive the at least one frequency-shifted beam from the at least one phase-shift channel and configured to direct the at least one frequency-shifted beam to an interferometer configured to acquire an interferogram of a sample with the at least one frequency-shifted beam.

Abstract: A concentration measurement method is performed using a concentration measurement device comprising: a measurement cell for flowing a fluid to be measured; a light source for generating light incident on the measurement cell; a photodetector for detecting light emitted from the measurement cell; an arithmetic unit for calculating the absorbance and concentration of the fluid to be measured based on an output of the photodetector; and a temperature sensor for measuring the temperature of the fluid to be measured.

Abstract: A system and method is provided for imaging and/or spectroscopy involving generation of a first signal field and a first idler field, illumination of the object with the first idler field, generation of second signal field and a second idler field, combination of the first and second idler fields, such that the two fields are indistinguishable, combination of the first and second signal fields, such that the two fields interfere, first measurement of the interfered signal field by a detection means, one or more additional measurements of the interfered signal field, wherein for each additional measurement a different phase shift is generated in the setup, and wherein all measurements are carried out within the stability time of the setup, and calculation of a phase function.

Abstract: Source light having a range of optical wavelengths is generated. The source light is split into sample light and reference light. The sample light is delivered into a sample, such that the sample light is scattered by the sample, resulting in signal light that exits the sample. The signal light and the reference light are combined into an interference light pattern having optical modes, each having a direct current (DC) component and at least one alternating current (AC) component. Different subsets of the optical modes of the interference light pattern are respectively detected, and analog signals representative of the optical modes of the interference light pattern are output. Pair of the analog signals are subtracted from each other, and differential analog signals are output. The sample is analyzed based on the differential analog signals.

Abstract: The present invention discloses a biodetector based on an interference effect of a thin film with ordered porous nanostructures. The biodetector includes a detection cell, a sensing unit disposed in the detection cell, and an optical fiber spectrometer for detecting reflectometric interference spectra of the sensing unit, wherein the sensing unit is an ordered porous thin film provided with three-dimensional ordered nanopores, and diameters of the nanopores are 20 nm-500 nm. The present invention further discloses a method for using the biodetector to detect biomolecules.

Abstract: The present disclosure relates to a common-path cube-corner retroreflector interferometer with a large optical path difference and high stability, and an interference technique thereof. The interferometer adopts an asymmetric common-path beam splitting structure using right-angled cube-corner retroreflectors, comprising a semi-transmissive and semi-reflective beam splitter, a plane mirror, a first right-angled cube-corner retroreflector, a second right-angled cube-corner retroreflector and an optical path difference element. The incident light is divided into a first transmitted beam and a second reflected beam, which are respectively reflected by the plane mirror and the right-angled cube-corner retroreflectors several times and then split again, two beams of which become interference outputs along directions perpendicular to an incident direction of the incident light, and the other two beams become interference outputs along directions parallel to the incident light.

Abstract: According to another embodiment, a method of detecting the occurrence of a condition using a detection system located within a predetermined area includes transmitting light from at least one node of a plurality of nodes into an ambient atmosphere adjacent the at least one node, receiving scattered light from the ambient atmosphere at the at least one node, communicating the received scattered light to a control system operably coupled to the at least one node, analyzing the scattered light at the control system to determine a condition of the ambient atmosphere adjacent each at least one node, and adjusting a sensitivity of the at least one node of the plurality of nodes.

Abstract: A method, apparatus, and system are provided to monitor and characterize the dynamics of a phase change region (PCR) created during laser welding, specifically keyhole welding, and other material modification processes, using low-coherence interferometry. By directing a measurement beam to multiple locations within and overlapping with the PCR, the system, apparatus, and method are used to determine, in real time, spatial and temporal characteristics of the weld such as keyhole depth, length, width, shape and whether the keyhole is unstable, closes or collapses. This information is important in determining the quality and material properties of a completed finished weld. It can also be used with feedback to modify the material modification process in real time.

Abstract: A light emitting structure for a photo-acoustic spectroscopy sensing device for sensing a target gas comprises a light source configured for emitting light of an input wavelength. The light emitting structure further comprises a conversion structure that is configured for absorbing light of the input wavelength, and that is further configured for emitting light of an output wavelength. The output wavelength of the conversion structure is adapted to an absorption wavelength of the target gas. The conversion structure comprises an output conversion layer that comprises a plurality of nanoparticles. The nanoparticles of the output conversion layer are configured for emitting light of the output wavelength.

Abstract: The invention relates to a method for creating a two-dimensional interferogram with a Michelson-type free-beam interferometer, comprising an extended, partially spatially coherent light source and a two-dimensional light detector, wherein light from the light source is split by a beam splitter with a semitransparent beam splitter mirror into a sample light beam and a reference light beam and taken to a sample arm and a reference arm, wherein the sample light beam returning from a sample is directed by the beam splitter mirror onto the light detector, wherein the reference light beam emerging from the reference arm makes a predetermined angle greater than zero with the sample light beam on the light detector, and wherein the length of the reference arm is variable, where the reference light beam is directed by means of an odd number of reflections in each reflection plane in at least one reference arm section so that it is displaced laterally to itself and travels antiparallel through a light-deflecting elemen

Abstract: Disclosed herein are a method for diagnosing a disease of a body tissue by using LIBS (Laser-Induced Breakdown Spectroscopy) comprising: preparing a laser device including: a laser projection module, outputting the laser to a suspicious region of the body tissue, a light receiving module, receiving a plurality of light, a spectrum measurement module, and a guide unit; and projecting the laser to generate plasma by inducing tissue ablation in the suspicious region; wherein the laser projected to the suspicious region has a target area, and wherein the target area has smaller size than the suspicious region such that the target area is located inside the suspicious region.

Abstract: The present invention relates to a method for the non-invasive optical characterization of a heterogeneous medium, comprising: a step of illuminating, by means of a series of incident light waves, a given field of view of the heterogeneous medium, positioned in a focal plane of a microscope objective (30); a step of determining a first distortion matrix (Dur, Drr) in an observation basis defined between a conjugate plane of the focal plane (FP) and an observation plane, said first distortion matrix corresponding, in a correction basis defined between a conjugate plane of the focal plane and an aberration correction plane, to the term-by-term matrix product of a first reflection matrix (Rur) of the field of view, determined in the correction basis, with the phase conjugate matrix of a reference reflection matrix, defined for a model medium, in said correction basis; and a step of determining, from the first distortion matrix, at least one mapping of a physical parameter of the heterogeneous medium.

Abstract: A method for measuring a thickness of a dielectric layer in a circuit board is provided. The method for measuring the thickness of the dielectric layer includes the following steps. First, a circuit board including at least one dielectric layer and at least two circuit layers is provided. The dielectric layer is between the circuit layers, and the circuit board further includes a test area including a test pattern and a through hole. The test pattern includes at least two metal layers. Next, a measuring device including a main body, at least one light source and a lens module is provided. When the main body is moved into the through hole, the light source emits light to the dielectric layer and the metal layer, and the lens module shoots the dielectric layer and the metal layer to form a captured image. The thickness of the dielectric layer is obtained via the captured image.

Abstract: In an observation method, measurement values of an object of measurement at a plurality of different positions in a plane that intersects a depth direction are acquired from an optical coherence tomography instrument (S100). In the observation method, measurement values are integrated in the depth direction at each of the plurality of positions (S104). In the observation method, a shrinkage parameter of the object of measurement is calculated on the basis of the integrated values at each of the plurality of positions (S105).