An interference observation apparatus includes a light source, a splitting beam splitter, a combining beam splitter, a beam splitter, a mirror, a beam splitter, a mirror, a piezo element, a stage, an imaging unit, an image acquisition unit, and a control unit. An interference optical system from the splitting beam splitter to the combining beam splitter forms a Mach-Zehnder interferometer. The mirror freely moves in a direction perpendicular to a reflecting surface of the mirror. The total number of times of respective reflections of first split light and second split light in the interference optical system is an even number.

A system for providing optical actuation and optical sensing can include an optical coherence tomography (OCT) device that performs optical imaging of a sample based on optical interferometry from an optical sampling beam interacting with an optical sample and an optical reference beam; an OCT light source to provide an OCT imaging beam into the OCT device which splits the OCT imaging beam into the optical sampling beam and the optical reference beam; and a light source that produces an optical actuation beam comprising a plurality of wavelengths that is coupled along with the optical sampling beam to be directed to the sample to actuate particles or structures in the sample so that the optical imaging captures information of the sample under the optical actuation.

An optical sensing device for a wheel set is provided. The optical sensing device comprises a first grating, a second grating, an elastic object and two optical sensors. The first grating is set in a first wheel of the wheel set. The second grating is set in a second wheel of the wheel set. The elastic object is connected between the first wheel and the second wheel, and is adapted to sustain a force applied when an angle difference is formed by a rotation of the second wheel with respect to the first wheel. The two optical sensors are set in a power module of the wheel set and provided respectively in correspondence to the first and the second gratings. The two optical sensors receive two optical signals reflected by the first and the second gratings, and the two optical sensors are used to calculate the angle difference.

A low coherence interferometry imaging system comprising a common-path interferometer that is at least partially integrated as part of a planar lightwave circuit is disclosed. Imaging systems in accordance with the present invention are implemented in integrated optics without the inclusion of highly wavelength-sensitive components. As a result, they exhibit less wavelength dependence than PLC-based interferometers of the prior art. Further, the common-path interferometer arrangement of the present invention avoids polarization and wavelength dispersion effects that plague prior-art PLC-based interferometers. Still further, an integrated common-path interferometer is smaller and less complex than other integrated interferometers, which makes it possible to integrate multiple interferometers on a single chip, thereby enabling multi-signal systems, such as plane-wave parallel OCT systems.

A photonic integrated circuit including a beam launching waveguide, a local oscillator waveguide, a target interferometer, and a reference interferometer all integrated on a chip. The beam launching waveguide transmits target electromagnetic radiation off the chip and receives a retroreflection of the target electromagnetic radiation from a target off the chip. The target interferometer interferes the retroreflection with a local oscillator field transmitted from the local oscillator waveguide so as to form a target interference signal. The reference interferometer interferes a portion of the target electromagnetic radiation that does not leave the chip with the local oscillator field transmitted from the local oscillator waveguide to form a reference interference signal. The difference between the reference interference signal and the target interference signal is used to measure a distance to the target from the chip.

An apparatus comprising: a double path interferometer comprising a sample path for an object and a reference path; a source of linearly polarized light for the double path interferometer, a phase plate positioned in the sample path; means for superposing the sample path and reference path to create a beam of light for detection; means for spatially modulating the beam of light to produce a modulated beam of light; means for dispersing the modulated beam of light to produce a spatially modulated and dispersed beam of light; a first detector; a second detector, and means for splitting the spatially modulated and dispersed beam of light, wherein light of a first linear polarization is directed to the first detector and light of a second linear polarization, orthogonal to the first linear polarization, is directed to the second detector.

A three-dimensional profiler includes a broadband radiation source. An interferometric system receives the radiation and includes first and second beam splitters, a moving time delay-inducing reflector, and a stationary reflector. The interferometric system creates a time-delayed optical sample radiation source and an optical reference incident radiation source with the first beam splitter. A stationary sample holder receives the optical sample incident radiation. A reference plane receives the optical reference incident radiation. A detector receives an interference signal from reflected or scattered optical sample radiation and reflected or scattered optical reference radiation. A processor extracts an optical path difference between the reference plane and the sample and reconstructs a three-dimensional morphology of the sample.

A three-dimensional profiler includes a broadband radiation source. An interferometric system receives the radiation and includes first and second beam splitters, a moving time delay-inducing reflector, and a stationary reflector. The interferometric system creates a time-delayed optical sample radiation source and an optical reference incident radiation source with the first beam splitter. A stationary sample holder receives the optical sample incident radiation. A reference plane receives the optical reference incident radiation. A detector receives an interference signal from reflected or scattered optical sample radiation and reflected or scattered optical reference radiation. A processor extracts an optical path difference between the reference plane and the sample and reconstructs a three-dimensional morphology of the sample.

An optical measurement apparatus (100) combines confocal measurement and low coherence interferometric measurement. The apparatus (100) comprises an interferometric measurement subsystem (102) and a confocal measurement subsystem (104) disposed within a housing (101). An optical combiner (136) is configured to provide the interferometric measurement subsystem (102) and the confocal measurement subsystem (104) with irradiative access to a region to be measured located at a substantially static target location. The interferometric measurement subsystem (102) and the confocal measurement subsystem (104) are respectively configured to image longitudinally in respect of a first subregion (162) and a second subregion (164) in the region to be measured. the second subregion (164) being axially spaced from the first subregion (162). A processing resource (152. 154) is operably coupled to the interferometric measurement subsystem (102) and the confocal measurement subsystem (104), and configured to calculate a first range in respect of the first subregion (162) and a second range in respect of the second subregion (164).

A method and a system for determining a displacement of an object are provided. The method includes: providing a predetermined modal power distribution characteristic; directing a light onto the object resulting in a reflected light; propagating the reflected light through different propagation modes, receiving a resulting modal power distribution characteristic; and comparing the resulting modal power distribution characteristic with the predetermined modal power distribution characteristic to determine the displacement of the object.