A method for measuring a spatial distortion of a target surface (110) of a workpiece (110A). Light is transmitted twice through a reference pattern-generator (104) and impinged upon a workpiece pattern-generator (108). Then, with an optical detector (116), first and second beams formed by the light as a result of interaction with two pattern- generators (104) (106) is acquired to produce a signal characterizing geometry of interference fringes formed at the detector (116) by the first and second beams. Indicia representing at least one of a type and a value of spatial distortion of the target surface (110) is generated and recorded. A system embodying the implementation of the method.

An optical position-measuring device includes a scale and a scanning reticle, whose relative position is determinable in three linearly independent spatial directions using interfering light beams. A splitter grating is disposed on the scanning reticle and adapted to split light into sub-beams of different diffraction orders. An optical grating is disposed on the scale and adapted to further split the sub-beams and to recombine them after they have been reflected back from the scanning reticle. Grating fields configured as phase gratings are disposed on a side of the scanning reticle that faces the scale. The grating fields act as diffractive optics that influence the further split sub-beams. The grating fields have different step heights. An output grating is disposed on the scanning reticle and adapted to output, as interfering sub-beams, light that has been multiply reflected between the scale and the scanning reticle.

A light detection device includes a light detector including first detectors and second detectors both disposed along a main surface; a light coupling layer disposed on or above the light detector; and a light shielding film disposed on the light coupling layer. The light coupling layer includes a first low-refractive-index layer, a first high-refractive-index layer that is disposed on the first low-refractive-index layer and includes a first grating, and a second low-refractive-index layer that is disposed on the first high-refractive-index layer. The light shielding film includes a light transmitting region and a light shielding region adjacent to the light transmitting region. The light transmitting region faces two or more first detectors included in the first detectors, and the light shielding region faces two or more second detectors included in the second detectors.

A system for measuring a target grating includes an illumination source, a reference transmission grating, a pupil filter, and a detector. The illumination source is disposed to generate an incident light beam that illuminates the reference transmission grating. The reference transmission grating splits the incident light beam into a plurality of diffraction orders. The plurality of diffraction orders interrogates a target grating. The reference transmission grating and the target grating are parallel. The pupil filter allows transmission of a subset of diffraction orders of light that has been diffracted and/or reflected from the target grating after being split again by passing through the reference transmission grating. The detector takes a measurement of the subset of diffraction orders of light after transmission through the pupil filter.

A displacement detection apparatus can reduce a measurement error even when a diffraction grating is displaced and/or tilted to a direction other than the measurement direction. A displacement detection apparatus includes a light source which emits light, a luminous flux-splitting section, a diffraction grating, a diffracted light-reflecting section, a correcting lens, a luminous flux-coupling section, and a light-receiving section. The diffracted light-reflecting section reflects a first luminous flux and a second luminous flux so as to be perpendicular to one of measuring planes of the diffraction grating and be parallel to each other. The correcting lens is arranged between the diffracted light-reflecting section and the diffraction grating.

According to one aspect, the invention relates to a device (100, 200, 300, 400, 500) for measuring the distance, with respect to a reference plane (P.sub.REF), from a point of light (P.sub.i) of an object (O). The device comprises a two-dimensional detector (30) comprising a detection plane (P.sub.DET) and an imaging system (10) adapted to form an image of a light spot (P.sub.i) situated on an object of interest plane (11) in an image plane (11) arranged in the vicinity of the detection plane (P.sub.DET) or a conjugate plane (P.sub.DET) of the detection plane. The device further comprises a separator element (20) for forming, from a beam emitted by a point of light of the object of interest plane (11), and emerging from the imaging system (10) at least two coherent beams, having a spatial superposition region in which the beams interfere and a signal processing means (50) for determining, from the interference pattern formed on the detection plane, and resulting from the optical interferences between said coherent beams, the distance from the point of light to a conjugate plane of the detection plane in the object space of the imaging system (10), said conjugate plane of the detection plane forming the reference plane (P.sub.REF).

Provided is a common-path optical fiber-based handheld parallel optical coherence tomography (OCT) apparatus, including a probe configured to receive the light from a broadband light source and illuminate a measurement target, wherein the probe may include an inner space through which the light passes, a collimator configured to collimate the light incident to the inner space, a diffraction grating configured to diffract the light having passed through the collimator, a galvanometer scanner configured to reflect the light having passed through the diffraction grating, an objective lens configured to concentrate the reflected light on a focal point, and an interferer configured to acquire an interfered light by reflecting at least a portion of the light having passed through the objective lens.

A photo-detection apparatus includes a light-shielding film, an optically-coupled layer, a photodetector, and an optical system. In the light-shielding film, light-transmitting regions and light-shielding regions are alternately arranged in at least a first direction within a plane. The optically-coupled layer faces the light-shielding film and includes a grating that propagates light in the first direction. The photodetector includes first photo-detection cells and second photo-detection cells arranged on an imaging area. The optical system is disposed between the optically-coupled layer and the photodetector. An image of light transmitted by parts of the optically-coupled layer that face each of the light-transmitting regions and light-shielding regions is enlarged or reduced by the optical system and formed on a corresponding one of the first and second photo-detection cells.

Provided is a common-path optical fiber-based handheld parallel optical coherence tomography (OCT) apparatus

The phase shift interferometer is configured to measure the shapes of measurement objects by acquiring a plurality of images of interference fringes while shifting the phases of the interference fringes. The interference fringes are provided with a phase difference of 90 relative to each other utilizing polarization of light. Images of the interference fringes are captured by two respective cameras while, in accordance with a conventional phase shift method, mechanically displacing a reference surface or a reference optical path to shift the phases. The phases of the interference fringes are calculated independently from the respective images acquired by the cameras and an average of the two phase calculation results is calculated.