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 spectrophotometer includes: an infrared light source; an interferometer; a first detector; and a monitor unit. The monitor unit includes: a second detector; and a light amount control unit. The light amount control unit is operable to control the infrared light source such that the amount comes closer to a target light amount, based on the signal. The infrared light source emits light having a first wavelength range and light having a second wavelength range different from the first wavelength range. The second detector includes: a first light detection element; and a second light detection element. The first light detection element outputs to the light amount control unit a first voltage corresponding to the light having the first wavelength range. The second light detection element outputs to the light amount control unit a second voltage corresponding to the light having the second wavelength range.

A beam splitter assembly includes a beam splitter, a holder that holds the beam splitter, and a first spacer group arranged between the beam splitter and the holder. The first spacer group includes three first spacer pieces. Each of the three first spacer pieces includes a first optical element holder and a first positioning portion. The holder includes three first spacer piece acceptance recesses. Each of the first spacer piece acceptance recesses is in a shape corresponding to the first positioning portion. The three first spacer pieces are accommodated in the three first spacer piece acceptance recesses, respectively. The first optical element holder of each of the three first spacer pieces abuts on the beam splitter.

The present disclosure relates to a common-path cube-corner retroreflector interferometer with a large optical path difference and high stability, and an interference technique thereof. The interferometer adopts an asymmetric common-path beam splitting structure using right-angled cube-corner retroreflectors, comprising a semi-transmissive and semi-reflective beam splitter, a plane mirror, a first right-angled cube-corner retroreflector, a second right-angled cube-corner retroreflector and an optical path difference element. The incident light is divided into a first transmitted beam and a second reflected beam, which are respectively reflected by the plane mirror and the right-angled cube-corner retroreflectors several times and then split again, two beams of which become interference outputs along directions perpendicular to an incident direction of the incident light, and the other two beams become interference outputs along directions parallel to the incident light. The present disclosure also provides an interference technique based on the interferometer described above.

Systems and methods for remote sensing in a plurality of dimensions simultaneously are provided. The plurality of dimensions include imaging, spectral sensing, and ranging at a range resolution that is orders of magnitude finer than the native time resolution of a detector used in the system.

A Fourier transform infrared spectrophotometer includes a main interferometer, a control interferometer, an infrared detector, a control light detector, a waveplate, and a support member. The waveplate is disposed on an optical path of a control light beam and between a fixed mirror or a moving mirror and a beam splitter. The support member supports the waveplate. An outer perimeter of the waveplate includes a supported region supported by the support member and a released region spaced apart from the support member.

An interferometer apparatus includes a beam splitter arranged for splitting an input beam into a first beam propagating along a first interferometer arm including a deflection mirror and a second beam propagating along a second interferometer arm including a deflection mirror. The first and second interferometer arms have an identical optical path length. A beam combiner is arranged for recombining the first and second beams into a constructive output and a destructive output. In the first interferometer arm compared with the second interferometer arm, one additional Fresnel reflection at an optically dense medium is provided and a propagation of the electromagnetic fields of the first and second beams, when recombined by the beam combiner, results in a wavelength-independent phase difference of π between the contributions of the two interferometer arms to the destructive output. Furthermore, an interferometric measurement apparatus and an interferometric measurement method are described.

A spectropolarimetric apparatus according to an embodiment of the present invention includes a light source attachment/detachment unit to which a light source is detachably coupled, a polarization interferometer configured to split light emitted from the light source coupled to the light source attachment/detachment unit into a plurality of polarized light beams using a polarization beam splitter and irradiate at least some of the split polarized light beams to a reflective sample to output the reflected light, and a spectrometer configured to measure physical properties of the reflective sample by analyzing the output light, wherein a wavelength of the light source coupled to the light source attachment/detachment unit varies depending on the reflective sample.

An otoscope uses differential reflected response of optical energy at an absorption range and an adjacent wavelength range to determine the presence of water (where the wavelengths are water absorption wavelength and adjacent non-absorption excitation wavelengths). In another example of the invention, the otoscope utilizes OCT in combination with absorption and non-absorption range for bacteria and water.

A wavelength-swept light source is configured to generate light to be measured that is wavelength-swept coherent light with a wavelength periodically changed. The light to be measured is separated into a measurement section and a reference section that have different optical path lengths, and is then coupled in an interference section to generate interfering light. An analyzer performs a Fourier transform of interference signals of the interfering light, and acquires an actual measured noise floor value for each of the optical path length differences based on a point spread function. An estimated coherence time is determined so that an actual measured amplitude value of the noise floor value and a calculated amplitude value coincide with each other. Linewidth of the light emitted from the coherent light source is measured based on the estimated coherence time.