An interferometer system including: an optical system arranged to split a radiation beam from a laser source into a first beam along a first optical path and a second beam along a second optical path, and recombine the first beam and the second beam to a recombined beam, a detector to receive the recombined beam and to provide a detector signal based on the received recombined beam, and a processing unit, wherein a first optical path length of the first optical path and a second optical path length of the second optical path have an optical path length difference, and wherein the processing unit is arranged to determine a mode hop of the laser source on the basis of a phase shift in the detector signal.

A laser interference device includes a measurement laser that outputs a laser beam, a beam splitter that divides the laser beam into a measurement laser beam and a frequency monitor laser beam, a reference laser that outputs a reference laser beam, a frequency detector that detects a beat frequency resulting from interference between the reference laser beam and the frequency monitor laser beam, a wavelength calculator that calculates a wavelength of the frequency monitor laser beam (a wavelength measurement value) on the basis of the beat frequency, a light detector that detects an interference light of the measurement light and the reference light of the measurement laser beam and outputs a light detection signal, and a displacement calculator that calculates a displacement of the measurement mirror by performing an arithmetic process based on the wavelength measurement value and the light detection signal.

Reference and test waves are directed in a common path mode in a fiber tip diffraction interferometer. A first fiber can be used to generate the reference wave and a second fiber can be used to generate the test wave. Each fiber can include a single mode fiber tip that defines a wedge at an end without a coating on end surface or a tapered fiber tip. The fiber tip diffraction interferometer can include an aplanatic pupil imaging lens or system disposed to receive both the test wave and the reference wave and a sensor configured to receive both the test wave and the reference wave.

An interferometer arrangement includes a beam splitter (8), two retroreflectors (15, 16), a drive (24) that moves at least one of the retroreflectors to alter an optical path difference between interferometer arms (13, 14), a converging element (18) for reference light, and a reference light detector (19) with at least three detector areas (19a-19d). First and second pairs of detector areas are aligned in respective first and second directions, wherein the first direction, the second direction and a central propagation direction of the reference light at the reference light detector are linearly independent. At least two actuators (9, 10) alter a lateral shear between two reference light partial beams (11, 12), which are reflected back from the interferometer arms and superimposed at the beam splitter, in at least two degrees of freedom. Control electronics (38) control the actuators depending on signals (Sa-Sc) at the detector areas, thereby minimizing the shear.

An interferometer system including: an optical system arranged to split a radiation beam from a laser source into a first beam along a first optical path and a second beam along a second optical path, and recombine the first beam and the second beam to a recombined beam, a detector to receive the recombined beam and to provide a detector signal based on the received recombined beam, and a processing unit, wherein a first optical path length of the first optical path and a second optical path length of the second optical path have an optical path length difference, and wherein the processing unit is arranged to determine a mode hop of the laser source on the basis of a phase shift in the detector signal.

The present invention relates to an arrangement and a method for single-shot interferometry which can be used for detecting distance, profile, shape, undulation, roughness or the optical path length in or on optically rough or smooth objects or else for optical coherence tomography (OCT). The arrangement comprises a light source, an interferometer, in which an end reflector is arranged in the reference beam path, and also a detector for detecting an interferogram. In the reference beam path of the interferometer, the end reflector can be embodied with three plane reflecting surfaces as a prism mirror or air mirror assembly in order to generate between reference and object beams a lateral shear of magnitude delta_q for obtaining a spatial interferogram. The embodiment of said assembly with regard to the angles and the arrangement of the reflecting surfaces makes possible a large aperture angle for a high numerical aperture. In the method, in the reference beam path it is possible to carry out a reduction of the aperture angle of the reference beam using beam-limiting means in order to achieve an optimum adaptation to the geometrically given aperture angle of the end reflector in the reference beam path, which is designed to be smaller than the aperture angle in the object beam path. The end reflector in the reference beam path can also be used as part of a second interferometer for high-resolution measurement of the displacement of the arrangement for single-shot interferometry, wherein said displacement serves for focusing. The end reflector is embodied as a triple reflection arrangement (e.g. a prism arrangement) having three reflecting surfaces. The triple reflection arrangement can have an M- or W-beam path, a non-intersecting zigzag beam path or an intersecting (zigzag) beam path.

A digital measuring device implemented on a photonic integrated circuit, the digital measuring device including a laser source implemented on the photonic integrated circuit configured to provide light, a first waveguide structure implemented on the photonic integrated circuit configured to direct a first portion of light from the laser source at a moving object and receive light reflected from the moving object, a second waveguide structure implemented on the photonic integrated circuit configured to combine a second portion of light from the laser source with the light reflected from the moving object to produce a measurement beam, a first multiplexer implemented on the photonic integrated circuit configured to split the measurement beam into a plurality of channels, and a plurality of detectors implemented on the photonic integrated circuit configured to detect an intensity value of each channel to measure a distance between the digital measuring device and the moving object.

Improved optical coherence tomography systems and methods to measure retinal data are presented. The systems may be compact, provide in-home monitoring, and have automation to allow the patient to measure himself or herself.

An interferometer system including: an optical system arranged to split a radiation beam from a laser source into a first beam along a first optical path and a second beam along a second optical path, and recombine the first beam and the second beam to a recombined beam, a detector to receive the recombined beam and to provide a detector signal based on the received recombined beam, and a processing unit, wherein a first optical path length of the first optical path and a second optical path length of the second optical path have an optical path length difference, and wherein the processing unit is arranged to determine a mode hop of the laser source on the basis of a phase shift in the detector signal.

A method of identifying the material and determining the physical thickness of each layer in a multilayer structure is disclosed. The method includes measuring the optical thickness of each of the layers of the multilayer object as a function of wavelength of a light source and calculating a normalized group index of refraction dispersion curve for each layer in the multilayer structure. The measured normalized group index of refraction dispersion curves for each of the layers is then compared to a reference database of known materials and the material of each layer is identified. The physical thickness of each layer is then determined from the group index of refraction dispersion curve for the material in each layer and the measured optical thickness data. A method for determining the group index of refraction dispersion curve of a known material, and an apparatus for performing the methods are also disclosed.