A laser interference device includes: a measurement mirror being movable in an X direction; a reference mirror disposed at a position different from a position of the measurement mirror in a Y direction; a beam splitter having a splitting surface that divides a laser beam into a measurement light and a reference light; a first light guide configured to guide the measurement light incident from the beam splitter and emit the measurement light toward the measurement mirror; and a second light guide configured to guide the reference light incident from the beam splitter and emit the reference light toward the reference mirror, in which a first distribution path formed by the first light guide and a second distribution path formed by the second light guide are mutually equal in a mechanical path length and an optical path length.

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.

A probe with optimized focal depth, working distance and axial light intensity uniformity, including a single-mode fiber for guiding light, a first gradient index fiber for improving light propagation efficiency and regulating mode energy, a large core fiber for generating mode interference field (MIF) and regulating an mode phase difference, a second gradient index fiber and a no-core fiber for magnifying the MIF, and a third gradient index fiber for focusing.

A processer of an optical module is configured to control a voltage signal having a frequency for causing a movable mirror to resonate, and perform an intensity acquisition process. The intensity acquisition process is a process of acquiring a measurement light intensity of the interference light of the measurement light M times at a first time interval based on the frequency in each of a plurality of cycles among P cycles continuous in the voltage signal, acquiring an addition value of a plurality of the measurement light intensities mutually corresponding for the same number of times, acquiring a laser light intensity of the interference light of the laser light N times at a second time interval based on the frequency in each of the plurality of cycles, and acquiring an addition value of a plurality of the laser light intensities mutually corresponding for the same number of times.

A processer of an optical module is configured to control a voltage signal having a frequency for causing a movable mirror to resonate, and perform an intensity acquisition process. The intensity acquisition process is a process of acquiring a measurement light intensity of the interference light of the measurement light M times at a first time interval based on the frequency in each of a plurality of cycles among P cycles continuous in the voltage signal, acquiring an addition value of a plurality of the measurement light intensities mutually corresponding for the same number of times, acquiring a laser light intensity of the interference light of the laser light N times at a second time interval based on the frequency in each of the plurality of cycles, and acquiring an addition value of a plurality of the laser light intensities mutually corresponding for the same number of times.

An OCT system includes an OCT optical system and a reference attachment. The OCT optical system has a beam splitter for splitting light into a measurement optical path and a reference optical path, a photodetector, a first waveguide, a second waveguide, and first connectors provided at end portions of the first waveguide and the second waveguide respectively for indirectly or directly connecting the first waveguide and the second waveguide. The reference attachment has a third waveguide, and second connectors formed at both ends of the third wave guide and configured to be attachable to and detachable from the first connector, and is attached to and detached from the OCT optical system h attaching and detaching each of the second connectors to and from the first connector to change an optical path length of the reference optical path.

An overlay metrology system may include, an illumination sub-system, a collection sub-system and a controller. The illumination sub-system may include one or more illumination optics configured to direct an illumination beam to an overlay target on a sample as the sample is scanned along a stage-scan direction by a translation stage, where the overlay target includes one or more cells having a grating-over-grating structure with periodicity along the stage-scan direction. The collection sub-system may include an objective lens, a first photodetector located in a pupil plane at a location of overlap between 0-order diffraction and +1-order diffraction, and a second photodetector located in a pupil plane at a location of overlap between 0-order diffraction and −1-order diffraction. The controller may receive time-varying interference signals from the first and second photodetectors and determine an overlay error between the first and second layers of the sample along the stage-scan direction.

An adjustable beam directing optical system for a focused laser differential interferometer (FLDI) instrument according to various aspects of the present technology may include an optical half waveplate to achieve an incident linear polarization orientation with equal components of laser intensity aligned to the vertical and horizontal axis of the optical system, and an optical prism for splitting these components of an incident laser beam into two orthogonally-polarized beams equally about an optical axis of the FLDI instrument. A series of beam realignment devices positioned downstream of the optical prism are configured to selectively direct each beam to a predetermined location.

A detection device adapted to detect lens surface and a stitching interferometer including the same are disclosed. The detection device includes: a cylindrical detection frame comprising support bosses arranged on an inner wall of the detection frame in a circumferential direction of the detection frame, the lens to be detected being placed on the support bosses; and a plurality of support units mounted at a bottom of the detection frame in the circumferential direction of the detection frame, each of the support units comprising: a support mechanism configured to be movable in an axial direction of the detection frame and cooperate with the support bosses so as to support the lens to be detected together; and a balance mechanism configured to provide a balancing force for balancing with force of the support mechanism for supporting the lens to be detected, so that axial support force of each supporting unit for the lens to be detected is equal to axial support force of each support boss for the lens to be detected in both cases where the axial direction of the detection frame is parallel to a gravity direction of the lens to be detected and inclined with respect to the gravity direction of the lens to be detected.

Systems and methods of producing unclonable devices are disclosed. Robust optical physical unclonable function devices use disordered photonic integrated circuits. Optical physical unclonable functions based on speckle patterns, chaos, or ‘strong’ disorder are so far notoriously sensitive to probing and/or environmental variations. A presently disclosed optical physical unclonable function is designed for robustness against fluctuations in optical angular/spatial alignment, polarization, and temperature using an integrated quasicrystal interferometer which sensitively probes disorder. All modes are engineered to exhibit approximately the same confinement factor in the predominant thermo-optic medium (e.g., silicon) and for constraining the transverse spatial-mode and polarization degrees of freedom. Silicon photonic quasicrystal interferometry is used for secure hardware applications.