A laser apparatus, a measurement apparatus, and a measurement method are provided in which the laser apparatus outputs a frequency-modulated laser beam with a plurality of modes and includes: an optical cavity that has a gain medium for amplifying a light to be input, and an optical SSB modulator for shifting a frequency of the light amplified by the gain medium: and a control part that controls the optical SSB modulator to shift a frequency of a light to be input to the optical SSB modulator.

An interferometric distance-measurement device includes a multi-wavelength light source which provides a beam having at least three different wavelengths. An interferometer unit splits the beam into measuring and reference beams. The measuring beam propagates in the direction of a measuring reflector movable along a measuring axis and undergoes a back-reflection, and the reference beam propagates in the direction of a stationary reference reflector and undergoes a back-reflection. The back-reflected measuring and reference beams interfere with each other in an interference beam. A detection unit splits the interference beam such that several phase-shifted partial interference signals result for each wavelength. A signal processing unit determines absolute position information regarding the measuring reflector from the partial interference signals of different wavelengths and an additional coarse position signal.

An interferometer having a fundamental beam generator, a first second harmonic generator, a waveplate, a second second harmonic generator, a harmonic separator, and a polarizing beam splitter, mounted uniaxially, (i.e., the components are aligned along one optical axis), wherein the interferometer is adapted to change a diameter of a beam to match a diameter of a sample, and to change the diameter of the beam back to its original diameter.

Defects are detected using data acquired from an interference channel and a polarization modification channel in an interferometer. The interference objective splits a polarized illumination beam into a reference illumination that is reflected by a reference surface without modification to the polarization, and a sample beam that is reflected by a sample surface, that may modify the polarization. Light from the sample beam with no change in polarization is combined with the reference illumination and directed to the interference channel, which may measure the reflectivity and/or topography of the sample. Light from the sample beam with modified polarization is directed to the polarization modification channel. The intensity of the light detected at the polarization modification channel may be used, along with the reflectivity and topography data to identify defects or other characteristics of the sample.

An interferometer movable mirror position measurement apparatus for determining a position of a movable mirror of an interferometer. The interferometer movable mirror position measurement apparatus including: a laser light source; a phase separation optical system configured to make first light and second light separately detected; a signal conversion unit configured to detect the first light and the second light in synchronization with a position of a movable mirror to generate a first sinusoidal wave signal and a second sinusoidal wave signal, respectively; a phase calculation unit configured to perform normalization and phase difference correction on each of the first sinusoidal wave signal and the second sinusoidal wave signal, and then calculate a phase of the first sinusoidal wave signal or the second sinusoidal wave signal at each time point; and a movable mirror position determination unit configured to determine a position of the movable mirror at a predetermined time point.

A truncated non-linear interferometer-based atomic force microscope (AFM) includes an input port and a non-linear amplifier that renders a probe beam and a conjugate beam. The AFM includes local oscillators having a relationship with the probe beam and the conjugate beam. The displacement of the AFM's cantilever is transduced by the probe beam, and/or the conjugate beam or their respective local oscillators. The AFM's phase-sensitive detectors detect a phase modulation between the respective local oscillators and the probe beam and the conjugate beam. The detected phase modulation corresponds to the change in phase. The AFM's circuitry measures phase signals that are indicative of the cantilever displacement. The resulting measurement signals exhibit a quantum noise reduction in either the intensity difference or phase sum quadrature.

Our high phase sensitivity wide-field phase cancellation interferometry system allows single-shot, label-free optical sensing of neural action potentials via imaging of optical path length changes. Single-shot sensing and monitoring of single neurons within a neural network should lead to a more comprehensive understanding neural network processing, which is beneficial for the advancement in the field of neuroscience as well as its biomedical applications and impact. Our system cancels the phase profile of the resting neuron from the phase profile of the spiking neuron, improving the sensitivity by two orders of magnitude. Using a detector with an extremely large well depth and an appropriately biased interferometer increases the sensitivity by another order of magnitude, yielding a measurement that is three orders of magnitude more sensitive than those possible with other microscopes.

A laser apparatus, a measurement apparatus, and a measurement method are provided in which the laser apparatus outputs a frequency-modulated laser beam with a plurality of modes and includes: an optical cavity that has a gain medium for amplifying a light to be input, and an optical SSB modulator for shifting a frequency of the light amplified by the gain medium: and a control part that controls the optical SSB modulator to shift a frequency of a light to be input to the optical SSB modulator.

An interferometer having a fundamental beam generator, a first second harmonic generator, a waveplate, a second second harmonic generator, a harmonic separator, and a polarizing beam splitter, mounted uniaxially, (i.e., the components are aligned along one optical axis), wherein the interferometer is adapted to change a diameter of a beam to match a diameter of a sample, and to change the diameter of the beam back to its original diameter.

A truncated non-linear interferometer-based atomic force microscope (AFM) includes an input port and a non-linear amplifier that renders a probe beam and a conjugate beam. The AFM includes local oscillators having a relationship with the probe beam and the conjugate beam. The displacement of the AFM's cantilever is transduced by the probe beam, and/or the conjugate beam or their respective local oscillators. The AFM's phase-sensitive detectors detect a phase modulation between the respective local oscillators and the probe beam and the conjugate beam. The detected phase modulation corresponds to the change in phase. The AFM's circuitry measures phase signals that are indicative of the cantilever displacement. The resulting measurement signals exhibit a quantum noise reduction in either the intensity difference or phase sum quadrature.