Inspecting a multilayer sample. In one example embodiment, a method may 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.

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.

In an optical device, an elastic support unit includes a pair of levers which face in a second direction perpendicular to a first direction, a pair of first torsion support portions which are connected between the levers and the base, a pair of second torsion support portions which are connected between the pair of levers and the movable unit, and a first link member that bridges the levers. The levers and the first link member define a light passage opening. Each of connection positions between the levers and the first torsion support portions is located on a side opposite to the movable unit with respect to the center of the light passage opening in a third direction perpendicular to the first direction and the second direction. A maximum width of the light passage opening in the second direction is defined by a gap between the levers in the second direction.

In an optical device, a base and a movable unit are constituted by a semiconductor substrate including a first semiconductor layer, an insulating layer, and a second semiconductor layer in this order from one side in a predetermined direction. The base is constituted by the first semiconductor layer, the insulating layer, and the second semiconductor layer. The movable unit includes an arrangement portion that is constituted by the second semiconductor layer. The optical function unit is disposed on a surface of the arrangement portion on the one side. The first semiconductor layer that constitutes the base is thicker than the second semiconductor layer that constitutes the base. A surface of the base on the one side is located more to the one side than the optical function unit.

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 optical function member 13 is provided with a light transmitting portion 14 that constitutes a part of an optical path between the beam splitter unit 3 and the fixed mirror 16. The light transmitting portion 14 is a portion that corrects an optical path difference that occurs between an optical path between the beam splitter unit 3 and the movable mirror 22 and the optical path between the beam splitter unit 3 and the fixed mirror 16. The second surface 21b of the base 21 and the 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 module 1 includes: a mirror unit 2 including a base 21, a movable mirror 22, and a fixed mirror 16; a beam splitter unit 3 that is disposed on one side of the mirror unit 2 in a Z-axis direction; a light incident unit 4 that causes measurement light L0 to be incident to the beam splitter unit 3; a first light detector 6 that is disposed on the one side of the beam splitter unit 3 in the Z-axis direction, and detects interference light L1 of measurement light which is emitted from the beam splitter unit 3; a support 9 to which the mirror unit 2 is attached; a first support structure 11 that supports the beam splitter unit 3; and a second support structure 12 that is attached to the support 9 and supports the first light detector 6.

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.

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.

A sensor is disclosed, wherein a transducer generates acoustic waves, which are received by a lens assembly. The lens assembly transmits and directs at least a part of the acoustic waves to a target. The lens assembly then receives at least a part of acoustic waves, after interaction with the target. The sensor further comprises an optical detector that comprises at least one optically reflective member located at a surface of the lens assembly, which surface is arranged opposite to a surface of the lens assembly which faces a focal plane of the lens assembly, wherein the at least one optically reflective member is mechanically displaced in response to the acoustic waves, which are received and transmitted by the lens assembly.