A three-dimensional measurement device includes: an optical system including an optical device that splits an incident light, irradiates a measurement object with a measurement light, irradiates a reference plane with a reference light, and combines at least part of the reflected measurement light with at least part of the reflected reference light to emit a combined light; a first light emitter that emits a first light that has a first wavelength; a second light emitter that emits a second light that has a second wavelength; a first imaging device that takes an image of an output light output from the optical device in which the first light enters; a second imaging device that takes an image of an output light output from the optical device in which the second light enters; and a control device that executes three-dimensional measurement of the measurement object.

An interferometric measurement system includes ports configured to receive an optical signal from an optical source and an optical signal from a target. A photonic integrated circuit includes a variable delay configured to select between at least two optical paths from the input to an output such that the optical signal from the optical source passes to the output while experiencing an optical delay based on a selected one of the at least two optical paths where a loss of the optical signal from the optical source provided to the input that passes to the output is nominally the same for each of the at least two optical paths. An optical receiver is configured to receive the optical signal from the target and to receive the optical signal from the optical source that experiences the optical delay based on the selected one of the at least two optical paths and generates a corresponding electrical receive signal at an electrical output. A processor is configured to generate an interferometric measurement signal based on the receive signal.

An interferometric measurement system includes ports configured to receive an optical signal from an optical source and an optical signal from a target. A photonic integrated circuit includes a variable delay configured to select between at least two optical paths from the input to an output such that the optical signal from the optical source passes to the output while experiencing an optical delay based on a selected one of the at least two optical paths where a loss of the optical signal from the optical source provided to the input that passes to the output is nominally the same for each of the at least two optical paths. An optical receiver is configured to receive the optical signal from the target and to receive the optical signal from the optical source that experiences the optical delay based on the selected one of the at least two optical paths and generates a corresponding electrical receive signal at an electrical output. A processor is configured to generate an interferometric measurement signal based on the receive signal.

Present disclosure relates to a heterodyne grating interferometric method and system for two-degree-of-freedom with high tolerance. The system comprises a separately modulated heterodyne laser (1), an optical prism (23) and a photoelectric detection and signal processing unit (4). The separately modulated heterodyne laser (1) simultaneously outputs two laser beams at different frequencies, which are incident in parallel to a first beamsplitting surface so as to be split, and then a part thereof is incident to a retro-reflector (233) to produce reference beams (53a, 53b), which are incident to a third beamsplitting surface, and the other part traverses a double-diffraction structure formed by a measured grating (3) and retro-reflectors (234a, 234b) to obtain two measured beams (59a, 59b), which are incident to a second beamsplitting surface and then are divided into two parts. Wherein one part is converged to form a first interference beam (61), and the other part is incident to the third beamsplitting surface and is converged with the corresponding reference beams (53a, 53b) to form second and third interference beams (62, 63). Photoelectric detection and signal processing is performed on the interference signals of the three interference beams (61, 62, 63), so as to calculate horizontal and vertical displacement of the grating (3). The present measurement method and system improve the angular tolerance of tip and tilt of the optical grating (3) while increasing the fold factors.

Present disclosure relates to a heterodyne grating interferometric method and system for two-degree-of-freedom with high tolerance. The system comprises a separately modulated heterodyne laser (1), an optical prism (23) and a photoelectric detection and signal processing unit (4). The separately modulated heterodyne laser (1) simultaneously outputs two laser beams at different frequencies, which are incident in parallel to a first beamsplitting surface so as to be split, and then a part thereof is incident to a retro-reflector (233) to produce reference beams (53a, 53b), which are incident to a third beamsplitting surface, and the other part traverses a double-diffraction structure formed by a measured grating (3) and retro-reflectors (234a, 234b) to obtain two measured beams (59a, 59b), which are incident to a second beamsplitting surface and then are divided into two parts. Wherein one part is converged to form a first interference beam (61), and the other part is incident to the third beamsplitting surface and is converged with the corresponding reference beams (53a, 53b) to form second and third interference beams (62, 63). Photoelectric detection and signal processing is performed on the interference signals of the three interference beams (61, 62, 63), so as to calculate horizontal and vertical displacement of the grating (3). The present measurement method and system improve the angular tolerance of tip and tilt of the optical grating (3) while increasing the fold factors.

Systems, methods, and media for multiple beam optical coherence tomography are provided which, in some embodiments, include: a light source; a splitter that outputs a fraction of light to various waveguides; optical components that receive light from the waveguides and direct the light as beams that simultaneously impinge a sample at different lateral positions, and collect backscattered light from the lateral positons; another splitter that outputs a fraction of light to waveguides of a reference arm as reference light samples; a mixer that receives the backscattered light samples and the reference light samples, and combines each backscattered sample with a corresponding reference sample such that the mixer outputs fringes; and a detector that receives the fringes, and outputs OCT signals, each indicative of a structure of the sample at a respective lateral position.

A method for characterising structures etched in a substrate, such as a wafer is disclosed. The method includes, for at least one structure, at least one interferometric measurement step, carried out with a low-coherence interferometer positioned on the top side of the substrate, for measuring with a measurement beam, at least one depth data relating to a depth of said HAR structure, wherein the method also includes a first adjusting step for adjusting a diameter, at the top surface, of the measurement beam according to at least one top-CD data relating to a width of said HAR structure. The invention further relates to a system implementing such a method.

A method for characterising structures etched in a substrate, such as a wafer is disclosed. The method includes at least one structure etched in the substrate, at least one imaging step including the following steps: capturing, with an imaging device positioned on a top side of said substrate, at least one image of a top surface of the substrate, and measuring a first data relating to the structure from at least one captured image, at least one interferometric measurement step, carried out with a low-coherence interferometer positioned on the top side, for measuring with a measurement beam positioned on the structure, at least one depth data relating to a depth of said structure; wherein the method also comprises a first adjusting step for adjusting said measurement beam according to the first data. A system implementing such a method is also disclosed.

The invention relates to the fields of optical technologies and telecommunication technologies, and is dedicated to determination of the direction of optical beam in free-space optical communication systems. The invention is based on the property of interference optical filters (IOF), that transmittance and reflectance of such filters, for a beam with given optical spectrum, depends on the angle of the beam with respect to IOF surface normal. According to the proposed method, at least one IOF is used, which is rotated by defined angle with respect to the optical axis of the detection device. In the implementation of the detection device with one IOF (4), two optical power detectors (6, 7) are used, which measure optical power of the beam reflected from the IOF (1′) and transmitted through the IOF (1″). Based on these measurements, the angle of the beam, with respect to the optical axis (5) of the device, is determined in one plane. To determine beam angle in another (perpendicular) plane, second beam angle detection device is used, which has IOF rotated in the perpendicular plane. After determining beam angles in both mutually perpendicular planes, full information regarding beam direction with respect of the optical axis of the system is acquired.

In some embodiments, systems, methods, and media for multiple reference arm spectral domain optical coherence tomography are provided which, in some embodiments, includes: a sample arm coupled to a light source; a first reference arm having a first path length; a second reference arm having a longer second path length; a first optical coupler that combines light from the sample arm and the first reference arm; a second coupler that combines light from the sample arm and the second reference arm; and an optical switch comprising: a first input port coupled to the first optical coupler; a second input coupled to the second coupler via an optical waveguide that induces a delay at least equal to an acquisition time of an image sensor; and an output coupled to the image sensor.