An optical module includes a mirror unit and a beam splitter unit. The mirror unit includes a base with a main surface, a movable mirror, a first fixed mirror, and a drive unit. The beam splitter unit constitutes a first interference optical system for measurement light along with the movable mirror and the first fixed mirror. A mirror surface of the movable mirror and a mirror surface of the first fixed mirror follow a plane parallel to the main surface and face one side in a first direction perpendicular to the main surface. The movable mirror, the drive unit, and at least a part of an optical path between the beam splitter unit and the first fixed mirror are disposed in an airtight space.

A fiber-optic sensors for measuring deformation, intended to operate in a harsh environment is provided. The sensor comprises a Fabry-Perot-cavity-based optical measurement head, a linking optical fiber and an expansion reserve case, the case comprising a segment of the linking optical fiber. The inside thickness of the case is comprised between one and several millimeters, the case being flat and of shape referred to as bicorne shape, the shape comprising a convex central portion and two concave symmetric ends, the optical fiber forming, inside the bicorne, one and only one arch, the segment of the optical fiber being, in addition, tangent to the internal surfaces of the reserve case, whatever the temperature conditions.

An optical module includes a mirror unit and a beam splitter unit. The mirror unit includes a base with a main surface, a movable mirror, a first fixed mirror, and a drive unit. The beam splitter unit constitutes a first interference optical system for measurement light along with the movable mirror and the first fixed mirror. A mirror surface of the movable mirror and a mirror surface of the first fixed mirror follow a plane parallel to the main surface and face one side in a first direction perpendicular to the main surface. The movable mirror, the drive unit, and at least a part of an optical path between the beam splitter unit and the first fixed mirror are disposed in an airtight space.

A mirror unit 2 includes a mirror device 20 including a base 21 and a movable mirror 22, an optical function member 13, and a fixed mirror 16 that is disposed on a side opposite to the mirror device 20 with respect to the optical function member 13. The mirror device 20 is provided with a light passage portion 24 that constitutes a first portion of an optical path between the beam splitter unit 3 and the fixed mirror 16. The optical function member 13 is provided with a light transmitting portion 14 that constitutes a second portion of the optical path between the beam splitter unit 3 and the fixed mirror 16. A second surface 21b of the base 21 and a third surface 13a of the optical function member 13 are joined to each other.

An optical module 1A includes a mirror unit 2 including a movable mirror 22 and a fixed mirror 16, a beam splitter unit 3, a light incident unit 4, a first light detector 6, a second light source 7, a second light detector 8, a holding unit 130, a first mirror 51, a second mirror 52, and a third mirror 53. The holding unit 130 holds the first light detector 6, the second light detector 8, and the second light source 7 so as to face that same side, and to be aligned in this order. A length of an optical path between the unit 3 and the detector 6 is shorter than a length of an optical path between the unit 3 and the detector 8, and a length of an optical path between the unit 3 and the source 7.

An optical metrology device produces beams of light with varying wavelengths in a spectral range for measurement of a sample that is at least partially transparent to the spectral range. The light is obliquely incident on the sample, where a portion of the light is reflected off the top surface and a portion is transmitted through the sample and is reflected off the bottom surface. The incident light and/or reflected light is polarized and a phase modulator, such as a photoelastic modulator or electrooptic modulator, is adjusted based on the wavelengths in each beam of light to produce a same retardation of polarization for each beam of light. The reflected light that is received by a detector does not include light reflected from the bottom surface of the sample. A characteristic of a buried structure below the top surface of the sample is determined using the detected reflected light.

A filtering device comprising first and second interference filters each comprising a Fabry-Perot cavity formed by semi-reflective layers between which a structured layer is arranged, wherein the structured layer belongs conjointly to the two filters, has a substantially constant thickness, is substantially planar and comprises two materials with different refractive indices arranged in each of the cavities, forming vertical structurings, the cavity of the second filter comprises a spacer arranged between one of the semi-reflective layers and the structured layer so that a distance between the semi-reflective layers of the cavity of the second filter is greater than a distance between the semi-reflective layers of the cavity of the first filter, and the filters comprise a second structured layer arranged in the cavities of the filters, and/or each filter comprises a second Fabry-Perot cavity comprising a third structured layer.

Inspecting a multilayer sample may include receiving, at a beam splitter, light and splitting the light into first and second portions; combining, at the beam splitter, the first portion of the light after being reflected from a multilayer sample and the second portion of the light after being reflected from a reflector; receiving, at a computer-controlled system for analyzing Fabry-Perot fringes, the combined light and spectrally analyzing the combined light to determine a value of a total power impinging a slit of the system for analyzing Fabry-Perot fringes; determining an optical path difference (OPD); recording an interferogram that plots the value versus the OPD for the OPD; performing the previous acts of the method one or more additional times with a different OPD; and using the interferogram for each of the different OPDs to determine the thicknesses and order of the layers of the multilayer sample.

An optomechanical inertial reference mirror combines an optomechanical resonator with a reflector that serves as an inertial reference for an atom interferometer. The optomechanical resonator is optically monitored to obtain a first inertial measurement of the reflector that features high bandwidth and high dynamic range. The atom interferometer generates a second inertial measurement of the reflector that features high accuracy and stability. The second inertial measurement corrects for drift of the first inertial measurement, thereby resulting in a single inertial measurement of the reflector having high bandwidth, high dynamic range, excellent long-term stability, and high accuracy. The reflector may be bonded to the resonator, or formed directly onto a test mass of the resonator. With a volume of less than one cubic centimeter, the optomechanical inertial reference mirror is particularly advantageous for portable atomic-based sensors and systems.

An optical metrology device produces light in a spectral range for measurement of a sample using a tunable Quantum Cascade Laser (QCL). The optical metrology device includes a second channel that is used to diagnose when the tunable QCL is in failure mode, e.g., when it is not producing all wavelengths in the plurality of different wavelength ranges. The second channel includes at least one optical flat that is transmissive to the light produced by the QCL and is separate from the tunable QCL. The optical flat is switchably placed in a beam path of the light produced by the tunable QCL and light transmitted through the optical flat is received by a detector. Using output signals from the detector, a failure mode of the tunable QCL may be determined.