Disclosed are a laser heterodyne interferometric apparatus based on plane mirror reflection and a corresponding method. The interferometric apparatus includes a dual-frequency laser, a first photoelectric receiver, a second photoelectric receiver, a first polarizing beamsplitter, a second polarizing beamsplitter, a third polarizing beamsplitter, a quarter-wave plate, a right angle mirror, an optical compensator, and a measured plane mirror. The method performs heterodyne interferometry with two spatially separated beams of different frequencies and balances the optical path lengths of the measurement beam and the reference beam with the optical compensator. In the method, the measured plane mirror moves back and forth along the propagation direction of the input beams. The disclosure suppresses optical non-linearity and optical thermal drift in laser heterodyne interferometry, simplifies the optical path structure, and improves accuracy of laser heterodyne interferometry.

A light interference unit includes a branching optical element, a multiplexing optical element, and at least one fiber device. The branching optical element branches a laser light with an emission wavelength temporally swept, into a measurement light and a reference light. The multiplexing optical element multiplexes the reference light and the measurement light reflected by a measured object, and causes them to interfere. The fiber device includes a reference light device. A transmission light path length is a light path length of the reference light transmitting the reference light device, from the reference light device to the multiplexing optical element. A reflection light path length is a light path length of the reference light reflected by a separation portion of the reference light device, from the reference light device to the multiplexing optical element. The transmission light path length is equal to or more than the reflection light path length.

A thickness measuring apparatus has a thickness measuring unit including a white light source, a diffracting mechanism that diffracts white light emitted from the white light source into diffracted light at time differences corresponding to the wavelengths of light components of the white light, a two-dimensional image sensor having a photodetection area that include a plurality of pixels for detecting return light reflected from upper and lower surfaces of a plate-shaped workpiece, a storage unit that stores, as a spectral interference waveform, intensities of the return light corresponding to the wavelengths of the light components successively received at the time differences by the pixels, and a waveform table recording therein a plurality of kinds of sample spectral interference waveforms corresponding to plate-shaped workpiece thicknesses.

Provided herein is technology relating to analysis of images and particularly, but not exclusively, to methods and systems for determining the area and/or volume of a region of interest using optical coherence tomography data. Some embodiments provide for determining the area and/or volume of a lesion in retinal tissue using three-dimensional optical coherence tomography data and a two-dimensional optical coherence tomography fundus image.

In certain embodiments methods of identifying T cell receptors that respond to specific target cell antigens are provided, where the methods comprise providing a substrate bearing a plurality of target cells (e.g., mammalian cells); contacting the target cells on the substrate with CD8+ T cells; and using label-free optical imaging to identify an increase in mass of a T-cell and/or a decrease in mass of a target cell, where an increase in mass of a T cell and/or a decrease in mass of a target cell is an indicator that said T cell bears a T cell receptor activated by antigens presented on said target cell.

Various optical systems equipped with diode laser light sources are discussed in the present application. One example system includes a diode laser light source for providing a beam of radiation. The diode laser has a spectral output bandwidth when driven under equilibrium conditions. The system further includes a driver circuit to apply a pulse of drive current to the diode laser. The pulse causes a variation in the output wavelength of the diode laser during the pulse such that the spectral output bandwidth is at least two times larger the spectral output bandwidth under the equilibrium conditions.

Disclosed are a laser heterodyne interferometric apparatus based on plane mirror reflection and a corresponding method. The interferometric apparatus includes a dual-frequency laser, a first photoelectric receiver, a second photoelectric receiver, a first polarizing beamsplitter, a second polarizing beamsplitter, a third polarizing beamsplitter, a quarter-wave plate, a right angle mirror, an optical compensator, and a measured plane mirror. The method performs heterodyne interferometry with two spatially separated beams of different frequencies and balances the optical path lengths of the measurement beam and the reference beam with the optical compensator. In the method, the measured plane mirror moves back and forth along the propagation direction of the input beams. The disclosure suppresses optical non-linearity and optical thermal drift in laser heterodyne interferometry, simplifies the optical path structure, and improves accuracy of laser heterodyne interferometry.

According to one embodiment, a three-dimensional (3D) measuring device is provided. The 3D measuring device includes a processor system that is configured to generate a point cloud representing multiple surfaces. The point cloud includes multiple scan points. Generating the point cloud includes receiving spherical coordinates for a scan point, the spherical coordinates comprising a distance (r), a polar angle (), and an azimuth angle (). Generating the point cloud further includes homogenizing a scan point density of the surfaces by filtering the scan points. The homogenizing includes computing a value (p) for the scan point based on the spherical coordinates. Based on the value exceeding a predetermined threshold, storing the scan point as part of the point cloud, and based on the value not exceeding the predetermined threshold, discarding the scan point.

A position measurement system including a first interferometer and a second interferometer arranged to determine a distance of the object in a first direction when the object is in a first measurement area by emitting beams onto a target surface of the object. The position measurement system further has a third interferometer and a fourth interferometer arranged to determine a distance of the object in the first direction when the object is in a second measurement area by emitting beams onto the target surface of the object. An arrangement of relative positions in a second direction of beams spots impinging on the target surface from the beams emitted by the first and second interferometers is different from an arrangement of relative positions in the second direction of beams spots impinging on the target surface from the beams emitted by the third and fourth interferometers.

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 element working by refraction or diffraction which is secured at the exit of the reference arm.