A truncated non-linear interferometer-based sensor system includes an input that receives an optical beam and a non-linear amplifier that generates a probe beam and a conjugate beam from the optical beam. The system's local oscillators are related to the probe beam and the conjugate beam. The system includes a sensor that transduces an input with the probe beam and the conjugate beam. The transduction detects changes in the phase of each of the probe beam and the conjugate beam. The system's phase sensitive detectors detect phase modulations between the respective local oscillators, the probe beam, and the conjugate beam and outputs phase signals based on detected phase modulations. The system measures phase signals indicative of the sensor's input resulting from a sum or difference of the phase signals. The measurement exhibits a quantum noise reduction in an intensity difference, a phase sum, or an amplitude difference quadrature.

A displacement detection device is capable of stably and accurately detecting an amount of displacement. A polarization maintaining fiber has a length not to be equal to a length obtained by dividing, a product of an integral multiple of twice a length of a resonator times a refractive index of the resonator and a beat length obtained from a difference between propagation constants of two polarization modes, by a wavelength of the light source, is selected from a range including a length equal to the above length. The polarization maintaining fiber includes multiple polarization maintaining fibers fitted to each other by removable connectors.

The invention discloses a four-quadrant interferometry system based on an integrated array wave plate. PBS splits an output laser light into two paths, the reflected light and the transmitted light are respectively transformed into reference light and measuring light, the reference light and the measuring light are converged in PBS, the converging light enters a signal receiving unit and is split into four beams, and the four beams irradiate on a four-quadrant interference signal detector with an integrated array wave plate. The invention solves the problems that the existing signal detection system occupies a large space, is not conducive to array integration, and cannot be used in scenes with high space and size requirements.

A truncated non-linear interferometer-based sensor system includes an input port that receives an optical beam and a non-linear amplifier that amplifies the optical beam with a pump beam and renders a probe beam and a conjugate beam. The system’s local oscillators have a relationship with the respective beams. The system includes a sensor that transduces an input with the probe beam and the conjugate beam or their respective local oscillators. It includes one or more phase-sensitive detectors that detect a phase modulation between the respective local oscillators and the probe beam and the conjugate beam. Output from the phase-sensitive-detectors is based on the detected phase modulation. The phase-sensor-detectors include measurement circuitry that measure the phase signals. The measurement is the sum or difference of the phase signals in which the measured combination exhibit a quantum noise reduction in an intensity difference or a phase sum or an amplitude difference quadrature.

Systems, devices and methods for measuring surface roughness and surface shape of an optical element using a dual-mode interferometer are disclosed. The devices implement optical filters, with a compact form, that allows measurement of both surface characteristics without rearranging the system components. One example interferometric system includes a laser light source and a low coherence light source that alternatively provide light to a collimator, followed by a polarizer, and a polarizing beam splitter. The system further includes two optical filters, a quarter waveplate, two objectives and a reference optical component. Each light source produces a set of interferograms, where one set of interferograms is used to measure the surface shape and another set of interferograms is used to measure the surface roughness of the optical component.

An optical device for characterizing a workpiece combines an interferometer with a polarization rotation pellicle, installed in a stand-alone fashion in a spatial gap between the mirrors of the interferometer, and a polarization based phase-shift sensor.

An atomic force microscope (“AFM”) based interferometer, uses a light source, and a splitting optical interface, splitting the light beam into a signal light beam and a reference light beam. Both the signal and reference light beams are focused in the vicinity of an AFM cantilever. A beam displacer introduces a lateral displacement between the signal light beam and reference light beam, the lateral displacement being such that, in at least one plane between the beam displacer and the focusing lens structure, the center of the signal light beam is separated from the center of the reference light beam by more than half a sum of their beam diameters on that plane. A detector operates to determine differences in optical path length between the signal light beam and reference light beam to determine information about movement of the cantilever.

Distance to a target is sensed using a common path interferometer, wherein a first fraction of light from a light source is collected after reflection by a partially reflective element together with reflection from a target of a second fraction of light from the light source that has been transmitted by the partially reflective element. The collected light is split in two parts, both containing a part of the first fraction and part of the reflection from the target. The parts are fed through a first and second optical branch path to an input side of a three-way optical coupler respectively. Light from at three terminals on a second side of the N way coupler is fed to respective light intensity detectors. Information representing an excess distance traveled by the first fraction from detection signals determined by the least three light intensity detectors.

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 multiple mirror for multiplying a single incident wavefront of electromagnetic radiation into a plurality of outgoing wavefronts, including at least one first mirror, onto which the incident wavefront first falls, and a second mirror, on which the wavefront is last reflected, wherein the mirror planes are superimposed in the direction of movement of the first wavefront. The first mirror is partially transparent to the electromagnetic radiation and the second mirror is fully reflective.