An apparatus comprising: a void; an interferometer detector; and light guide means for guiding a light signal along a light path to the interferometer detector wherein the light path comprises a cantilever light guide that is supported such that a free-end can move within the void and the interferometer detector is configured to detect a deflection of the free-end of the cantilever light guide; and a reflector, wherein the cantilever light guide comprises a light outcoupler configured to out-couple the light signal to extend the light path from the cantilever light guide to the reflector.

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 beam of light along a first optical path (11); a sensor (3) able to evaluate the effects of the electromagnetic interference of the first beam; an optical splitter (4) located upstream of the sensor (3), generating, from the first beam of light, a second beam of light along a second optical path (12); a focusing lens (5, 6) located on the first and/or the second optical path (11, 12), focusing the beam of light at a distance f and defining an upstream optical path (11′, 12′), and a means (7) for routing the second beam, comprising a mirror redirecting the second path such that the lengths of the first (11′) and second (12′) paths are different.

An Optical Coherence Tomography receiver may include prisms, polarizing beam splitters, reflectors, lenses, and a photodetector array arranged in a compact package. Sample and reference beams are combined into an interference beam and split in two. The two resulting interference beams are then split into two polarization sates each. The optical path lengths for both pairs of interference beams with the same polarization state are equal or nearly equal.

An Optical Coherence Tomography receiver may include prisms, polarizing beam splitters, reflectors, lenses, and a photodetector array arranged in a compact package. Sample and reference beams are combined into an interference beam and split in two. The two resulting interference beams are then split into two polarization sates each. The optical path lengths for both pairs of interference beams with the same polarization state are equal or nearly equal.

Interferometric speckle visibility spectroscopy methods, systems, and non-transitory computer readable media for recovering sample speckle field data or a speckle field pattern from an off-axis interferogram recorded by one or more sensors over an exposure time and determining sample dynamics of a sample being analyzed from speckle statistics of the speckle field data or the speckle field pattern.

A time-domain or frequency domain including a sample light path between a source interface and a detector interface, a reference light path between the source interface and the detector interface, and a photonic integrated circuit, wherein the reference light path is at least partially separate from the sample light path, wherein the sample light path comprises a forward sample light path between the source interface and a sample interface, and a backward sample light path between the sample interface and the detector interface, wherein the forward sample light path and the backward sample light path are at least partially provided by the photonic integrated circuit, and wherein the photonic integrated circuit comprises an integrated sample-side polarization beam splitter arranged in the forward sample light path and the backward sample light path.

The invention relates to a method for creating a two-dimensional interferogram with a Michelson-type free-beam interferometer, comprising an extended, partially spatially coherent light source and a two-dimensional light detector, wherein light from the light source is split by a beam splitter with a semitransparent beam splitter mirror into a sample light beam and a reference light beam and taken to a sample arm and a reference arm, wherein the sample light beam returning from a sample is directed by the beam splitter mirror onto the light detector, wherein the reference light beam emerging from the reference arm makes a predetermined angle greater than zero with the sample light beam on the light detector, and wherein the length of the reference arm is variable, where the reference light beam is directed by means of an odd number of reflections in each reflection plane in at least one reference arm section so that it is displaced laterally to itself and travels antiparallel through a light-deflecting element working by refraction or diffraction which is secured at the exit of the reference arm.

The invention relates to a method for creating a two-dimensional interferogram with a Michelson-type free-beam interferometer, comprising an extended, partially spatially coherent light source and a two-dimensional light detector, wherein light from the light source is split by a beam splitter with a semitransparent beam splitter mirror into a sample light beam and a reference light beam and taken to a sample arm and a reference arm, wherein the sample light beam returning from a sample is directed by the beam splitter mirror onto the light detector, wherein the reference light beam emerging from the reference arm makes a predetermined angle greater than zero with the sample light beam on the light detector, and wherein the length of the reference arm is variable, where the reference light beam is directed by means of an odd number of reflections in each reflection plane in at least one reference arm section so that it is displaced laterally to itself and travels antiparallel through a light-deflecting element working by refraction or diffraction which is secured at the exit of the reference arm.

The invention relates to a device for measuring a substrate for semiconductor lithography with a reference interferometer for ascertaining the change in the ambient conditions, wherein the reference interferometer comprises a means for changing the optical path length of a measurement section of the reference interferometer, wherein the means is configured to bring about a change in the refractive index.

Furthermore, the invention relates to a method for correcting cyclic error components of a reference interferometer, wherein the reference interferometer comprises a means for changing the optical path length of a measurement section of the reference interferometer, comprising the following method steps: starting up the reference interferometer, continuously detecting measurement values of the reference interferometer, changing the optical path length of the measurement section of the reference interferometer until a path length change of at least one quarter of the wavelength of the reference interferometer is detected, determining the cyclic errors on the basis of the continuously detected measurement values of the reference interferometer, and correcting the current measurement values ascertained by the reference interferometer on the basis of the cyclic errors ascertained.

The invention relates to a device for measuring a substrate for semiconductor lithography with a reference interferometer for ascertaining the change in the ambient conditions, wherein the reference interferometer comprises a means for changing the optical path length of a measurement section of the reference interferometer, wherein the means is configured to bring about a change in the refractive index.

Furthermore, the invention relates to a method for correcting cyclic error components of a reference interferometer, wherein the reference interferometer comprises a means for changing the optical path length of a measurement section of the reference interferometer, comprising the following method steps: starting up the reference interferometer, continuously detecting measurement values of the reference interferometer, changing the optical path length of the measurement section of the reference interferometer until a path length change of at least one quarter of the wavelength of the reference interferometer is detected, determining the cyclic errors on the basis of the continuously detected measurement values of the reference interferometer, and correcting the current measurement values ascertained by the reference interferometer on the basis of the cyclic errors ascertained.