Improvements to atom interferometers. An improved atom interferometer has a single polarization-preserving fiber, coupled for propagation of beams of two Raman frequencies, and a parallel displacement beamsplitter for separating the laser beams into respective free-space-propagating parallel beams traversing at least one ensemble of atoms. A reflector generates one or more beams counterpropagating through the ensemble of atoms. Other improvements include interposing a beam-splitting surface common to a plurality of parallel pairs of beams counterpropagating through the ensemble of atoms, generating interference fringes between reflections of the beams to generate a detector signal; and processing the detector signal to derive at least one of relative phase and relative alignment between respective pairs of the counterpropagating beams.

A compact, low cost FTIR spectrometer with no moving parts includes an interferometer having optical paths through silicon waveguides. The optical path lengths are varied by changing the temperature and/or carrier density of at least one of the waveguides. In embodiments, the interferometer is a Mach-Zehnder interferometer. Embodiments vary both optical path lengths in opposite directions. In embodiments, a germanium or InGaAs IR detector is grown on the same wafer as the waveguides. Embodiments include a laser pump, such as a COT CW diode laser, and wavelength mixer, such as an OPGaAs or OPGaP converter, for up and/or down converting measured IR wavelengths into a range compatible with the waveguide and detector materials. The wavelength mixer can be a waveguide. Embodiments include a sample compartment and an IR source such as a glowbar. In embodiments, the sample compartment can be exposed to ambient atmosphere for analysis of gases contained therein.

The object of the present invention is a measurement method and a system for measurement of an amplitudes ratio of two first harmonics of a signal obtained from the Sagnac fibre-optic inter-ferometer system as well as the Sagnac fibre-optic system, and an application of the said system to measure the amplitude ratio of two first harmonics obtained from the Sagnac fibre-optic system and the Sagnac fibre-optic interferometer system for detection of rotational movements, in particular seismic rotational movements and rotational movements of structures.

The invention relates to a control system (100) for a fiber optic gryoscope, comprising a phase modulator (110) for modulating a phase of a light signal (115) and a control unit (120) for producing a control signal (125), by the value of which the phase is modulated and which is fed to the phase modulator (110). The control signal changes statistically and does not have an average value.

An interferometric displacement measurement apparatus (100) includes at least one measurement interferometer (103) for measuring a change in optical path difference between a measurement beam (150) and a reference beam. A light source module (118) is arranged to generate a modulated light beam, having a particular optical spectrum, from which the measurement beam and reference beam are derived. A data acquisition and analysis module (105) can determine a measure representative of the displacement using interference intensity data received from a photodetector (111) which detects the interference of the measurement beam with the reference beam.

A system for measuring a target grating includes an illumination source, a reference transmission grating, a pupil filter, and a detector. The illumination source is disposed to generate an incident light beam that illuminates the reference transmission grating. The reference transmission grating splits the incident light beam into a plurality of diffraction orders. The plurality of diffraction orders interrogates a target grating. The reference transmission grating and the target grating are parallel. The pupil filter allows transmission of a subset of diffraction orders of light that has been diffracted and/or reflected from the target grating after being split again by passing through the reference transmission grating. The detector takes a measurement of the subset of diffraction orders of light after transmission through the pupil filter.

Provided is a snapshot spectral domain optical coherence tomographer comprising a light source providing a plurality of beamlets; a beam splitter, splitting the plurality of beamlets into a reference arm and a sample arm; a first optical system that projects the sample arm onto multiple locations of a sample; a second optical system for collection of a plurality of reflected sample beamlets; a third optical system projecting the reference arm to a reflecting surface and receiving a plurality of reflected reference beamlets; a parallel interferometer that provides a plurality of interferograms from each of the plurality of sample beamlets with each of the plurality of reference beamlets; an optical image mapper configured to spatially separate the plurality of interferograms; a spectrometer configured to disperse each of the interferograms into its respective spectral components and project each interferogram in parallel; and a photodetector providing photon quantification.

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.

An optical coherence tomography scanning system traverses its respective scan pattern quickly, typically completing an entire two-dimensional frame faster than a conventional raster scanner completes one raster line segment. To traverse the scan pattern quickly, the system takes fewer A-scans per length of scan pattern than a conventional OCT scanner. To compensate for the sparsity of the sample points along the respective scan line segments, and for gaps between respective line segments of the trajectory, the system acquires and combines several partially overlapping frames for each study.

Various optical systems equipped with diode laser light sources are discussed in the present application. One example system includes a diode laser light source for providing a beam of radiation. The diode laser has a spectral output bandwidth when driven under equilibrium conditions. The system further includes a driver circuit to apply a pulse of drive current to the diode laser. The pulse causes a variation in the output wavelength of the diode laser during the pulse such that the spectral output bandwidth is at least two times larger the spectral output bandwidth under the equilibrium conditions.