An ellipsometer includes a first separation unit configured to separate a first reflected light into two reflected lights, a first polarizing optical element configured to separate each of the two reflected lights into two linearly polarized lights, a first interference device configured to form an interference fringe by allowing components of the two linearly polarized lights to interfere with each other, a second separation unit configured to separate a second reflected light into two reflected lights, a second polarizing optical element configured to separate each of the two reflected lights into two linearly polarized lights, and a second interference device configured to form an interference fringe by allowing components of the two linearly polarized lights to interfere with each other.

An optical device for characterizing a workpiece combines an interferometer with a polarization rotation pellicle, installed in a stand-alone fashion in a spatial gap between the mirrors of the interferometer, and a polarization based phase-shift sensor.

A laser measurement system for measuring up to 21 geometric errors, in which a six-degree-of-freedom geometric error simultaneous measurement unit and a beam-turning unit are mounted on either the clamping workpiece or the clamping tool, while an error-sensitive unit is mounted on the remaining one, the beam-turning unit has several switchable working postures and multi-component combinations in its installation state, it can split or turn the laser beam from the six-degree-of-freedom geometric error simultaneous measurement unit to the X, Y, and Z directions in a proper order, or the beam-turning unit can split or turn a beam from the error-sensitive unit to the six-degree-of-freedom geometric error simultaneous measurement unit. The present invention is of simple configuration and convenient operation. Up to 21 geometric errors of three mutual perpendicular linear motion guides are obtained by a single installation and step-by-step measurement.

Optical coherence tomography (OCT) systems using a polarization switch and/or a polarization beam splitter are generally described. In an example, an OCT system includes a light source configured to emit a beam and an interferometer configured to receive the beam. The interferometer includes a reference path and an interferometer sample path. The OCT system further includes a polarization switch configured to selectively change a polarization state of the beam and a lens system that includes a first sample path and a second sample path. The polarization switch is further configured to direct the beam onto the first sample path upon selection of a first polarization state and to direct the beam onto the second sample path upon selection of a second polarization state that is different from the first polarization state.

An atomic interferometric accelerometer comprises a laser that emits a pulsed beam at a first frequency, an electro-optic modulator that receives the beam, and a vacuum cell in communication with the electro-optic modulator. The electro-optic modulator outputs a first optical signal corresponding to the beam at the first frequency and a second optical signal having a second frequency different from the first frequency. The vacuum cell has a chamber for laser cooled atoms. The vacuum cell receives the optical signals such that they propagate in a direction that passes through the atoms. A piezo mirror retro-reflects the optical signals back through the vacuum cell in a counter-propagating direction. The piezo mirror is driven with substantially constant velocity during a beam pulse, thereby imparting a Doppler shift to the retro-reflected optical signals to create two non-symmetric counter-propagating lightwave pairs. One of the lightwave pairs supports interferometry while the other is non-resonant.

An interferometer includes a light source, a beam splitter, a reference reflector, a measuring reflector, a detection unit, and at least two transparent plane-parallel plates. The beam splitter splits a beam of rays into at least one measuring beam and at least one reference beam. Until being recombined, the measuring beam propagates in a measuring arm, and the reference beam propagates in a reference arm. The reference beam falls at least three times on the reference reflector located in the reference arm. The measuring reflector is disposed in the measuring arm and is joined to an object to be measured, which is movable along a measuring direction relative to the reference reflector. The measuring beam falls at least three times on the measuring reflector. At least one distance signal with regard to the position of the object to be measured is ascertainable from the interfering measuring and reference beams via the detection unit. The plane-parallel plates are disposed parallel to each other in the beam path between the light source and the detection unit. At least the measuring reflector is movable relative to the plane-parallel plates along the measuring direction. The plane-parallel plates each include a plurality of optical elements that exert such an optical effect on the measuring beam and the reference beam that they propagate parallel to each other in the direction of the measuring reflector and reference reflector, respectively.

The invention relates to an optical coherence microscopy system for fast, phase resolved imaging by means of optical coherence microscopy with decoupled illumination and detection apertures, producing a dark-field effect with an enhanced optical contrast. The setup uses a light source with an appropriate temporal coherence, an interferometer and an array detector combined with a spectrometer. The dark-field effect is produced by optical filter means in the illumination and detection paths, positioned in conjugated planes of the sample microscope objective. These optical means comprise for example refractive or diffractive elements, amplitude or phase masks, or programmable spatial light modulators. The object is scanned via a scanning unit allowing a point scan of the object.

The disclosure discloses a differential sinusoidal phase modulation laser interferometric nanometer displacement measuring apparatus and method. The beam output from the single-frequency laser is converted into a 45° linearly polarized beam after passing through the polarizer, then projected onto two sets of sinusoidal phase modulation interferometers consisting of the beam splitter, the electro-optic phase modulator, the half wave plate, three pyramid prisms, two polarization beam splitters, thereby forming measurement and reference interference signals which are received by two photodetectors. A high-frequency sinusoidal voltage signal is applied to the electro-optic phase modulator placed in the common reference arm of the two interferometers, thereby modulating the interference signal into a high-frequency AC signal. By detecting the difference between the phase change amounts of the two interference signals when the measured object moves, the measured displacement can be obtained.

Polarization-based coherent gradient-sensing systems and methods for measuring at least one surface-shape property of a specularly reflective surface are disclosed. The method includes: reflecting a first circularly polarized laser beam from a sample surface to form a second circularly polarized laser beam that contains surface-shape information; converting the second circularly polarized laser beam to a linearly polarized reflected laser beam; directing respective first and second portions of the linearly polarized reflected laser beam to first and second relay assemblies that constitute first and second interferometer arms. The first and second relay assemblies each use a pair of axially spaced-apart gratings to generate respective first and second interference patterns at respective first and second image sensors. Respective first and second signals from the first and second image sensors are processed to determine the at least one surface-shape property.

A multiple mirror for multiplying a single incident wavefront of electromagnetic radiation into a plurality of outgoing wavefronts, including at least one first mirror, onto which the incident wavefront first falls, and a second mirror, on which the wavefront is last reflected, wherein the mirror planes are superimposed in the direction of movement of the first wavefront. The first mirror is partially transparent to the electromagnetic radiation and the second mirror is fully reflective.