A digital holography metrology system is provided including a heterodyne light source, an interferometric optical arrangement and a sensor arrangement. The heterodyne light source provides combined laser beams of different corresponding frequencies and wavelengths (e.g., for which each combined beam may include a corresponding wavelength laser beam and a corresponding frequency shifted laser beam, which may be orthogonally polarized). The interferometric optical arrangement utilizes the combined beams for providing an output for imaging a workpiece, for which the output includes interference beams. The sensor arrangement includes dichroic components which separate the interference beams to be directed to respective time of flight sensors. The outputs from the time of flight sensors are utilized to determine measurements (e.g., the outputs of the time of flight sensors may be utilized to determine a measurement distance to a surface point on a workpiece, etc.).

A metrology system including a heterodyne light source is provided. The heterodyne light source includes a first light source, an acousto-optic modulator and a source optical arrangement. The acousto-optic modulator receives at least one wavelength laser beam from the first light source and generates at least one corresponding frequency shifted laser beam (e.g., with orthogonal polarization). The source optical arrangement includes a receiving optical element portion and a birefringent optical element portion. The receiving optical element portion receives the wavelength laser beam(s) and the corresponding frequency shifted laser beam(s) and directs the beams along an optical path toward the birefringent optical element portion. The birefringent optical element portion combines the beams to output a combined beam (e.g., which may be utilized as part of a measurement process to determine at least one measurement distance to at least one surface point on a workpiece, etc.).

Improved optical coherence tomography systems and methods to measure thickness of the retina are presented. The systems may be compact, handheld, provide in-home monitoring, allow the patient to measure himself or herself, and be robust enough to be dropped while still measuring the retina reliably.

Disclosed are devices and techniques based on optical coherence tomography (OCT) technology in combination with optical actuation. 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 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.

A method for measuring the surface topography of an object including the following steps: a) providing source radiation and dividing the source radiation into illumination radiation and reference radiation, b) illuminating the surface of the object with illumination radiation in a planar illumination field, the surface of the object being illuminated simultaneously with more than one spatial radiation mode and the radiation modes of the illumination being spatially and temporally coherent, but with a fixed phase difference from one another, and c) overlaying the reference radiation on illumination radiation back-scattered at the surface of the object, and detecting an interference signal of the overlaid radiation with a detector. Steps a) to c) are carried out for at least two different, fixed wavelengths. The surface topography of the object is determined by means of digital holography.

An opto-electronic dual-comb interferometric distance measuring method and device wherein a signal comb is chromatically divided into a target signal comb and a non-target signal comb at a emission position, preferably by an optical interleaver in a measurement probe of the device. Only the target signal comb serves as a free beam emitted to the target. The non-target signal comb serves for generation of additional or compensation internal phase differences. Thus, the distance to the target is based on first, target related phase differences and on the second, internal compensation phase differences.

Apparatus for detecting a 3D structure of an object, comprising at least three laser emitters and a beam splitter that splits the laser radiation of the laser emitters into a reference radiation and an illumination radiation. The illumination radiation strikes the object to be measured, is reflected by the object as object radiation and interferes with the reference radiation. A detector receives the interference patterns formed from the interference of the reference and object radiation and an analysis unit analyzes the interference patterns. At least two of the laser emitters emit laser radiation in the invisible range and the analysis unit detects the object in three dimensions based on the interference patterns of the invisible laser radiation. At least one of the laser emitters emits colored laser radiation and the analysis unit deduces the object's color based on the intensity of the colored object radiation reflected by the object.

A device for absolute distance measurement includes a first tunable light source for emitting a first wavelength light of a first tunable frequency modulated by a first modulating frequency and a second light source for emitting a second wavelength light of a second frequency modulated by a second modulating frequency. An optical coupler couples the first wavelength light and the second wavelength light into an interferometer cavity. An interferometer detector provides an interference measurement signal based on a detected interference pattern. A demodulator unit generates a first demodulation signal based on the interference measurement signal by demodulation with the first modulating frequency and a second demodulation signal based on the interference measurement signal by demodulation with the second modulating frequency. A computation unit computes an absolute distance by evaluating the first demodulation signal acquired during a sweep of the first tunable frequency and the second demodulation signal.

The invention provides a method for calibration of an optical measurement system, which may be a heterodyne interferometer system, wherein a first optical axis and a second optical axis have a different optical path length, the method comprises: .sup.∘measuring a first measurement value along the first optical axis using a first measurement beam, .sup.∘measuring a second measurement value along the second optical axis using a second measurement beam, .sup.∘changing a wavelength of the first measurement beam and the second measurement beam, .sup.∘measuring a further first measurement value along the first optical axis using the first measurement beam with changed wavelength, measuring a further second measurement value along the second optical axis using the second measurement beam with changed wavelength, .sup.∘determining a cyclic error of the optical measurement system on the basis of the measured values, and .sup.∘storing a corrective value based on the cyclic error.

A system (1) for generating a signal from a surface (22) having a speed V in a direction U, comprising: a light source (2) emitting a Gaussian light beam along a first optical path (11); a sensor (3) able to evaluate the effects of the electromagnetic interference of the first beam; a means (2′, 4) for generating a second Gaussian light beam along a second optical path (12); a second sensor (3′) able to evaluate the effects of electromagnetic interference of the second beam; a focusing lens (5, 6) located on the first and/or the second optical path (11, 12), focusing the light beam at a distance f and defining an upstream optical path (11′, 12′); and a means (4′, 7) for routing the second beam able to redirect the second path (12′) in the direction of the first path (11′).