A method of determining residual intensity noise (RIN) of a sensor may comprise determining a first amplitude of a first harmonic of the sensor while a signal propagating through the sensor is modulated at a modulating frequency corresponding to twice an eigenfrequency of the sensor. The method may further comprise determining a second amplitude of a second harmonic of the sensor while the signal propagating through the sensor is modulated the modulating frequency, and determining the RIN of the sensor as a ratio of the first amplitude and the second amplitude.

Embodiments described herein provide for metrology tools and methods of obtaining a full-field optical field of an optical device to determine multiple metrology metrics of the optical device. A metrology tool is utilized to split a light beam into a first light path and a second light path. The first light path and the second light path are combined into a combined light beam and delivered to the detector. The detector measures the intensity of the combined light beam. A first equation and second equation are utilized in combination with the intensity measurements to determine an amplitude and phase Ψ at a reference point directly adjacent to a second surface of the at least one optical device.

An optical measurement system comprises a polarization beam splitter for dividing an incident beam into a reference beam and a measurement beam, a first beam splitter for reflecting the measurement beam to form a first reflected measurement beam, a spatial light modulator for modulating the first reflected measurement beam to form a modulated measurement beam, a condenser lens for focusing the modulated measurement beam to an object to form a penetrating measurement beam, an objective lens for converting the penetrating measurement beam into a parallel measurement beam, a mirror for reflecting the parallel measurement beam to form an object beam, a second beam splitter for reflecting the reference beam to a path coincident with that of the object beam, and a camera for receiving an interference signal generated by the reference beam and the object beam to generate an image of the object.

An acousto-optic modulator (AOM) laser frequency shifter system includes a laser configured to generate an incident beam, a first optical splitter optically coupled to the laser and configured to split the incident beam into at least one portion of the incident beam, at least one phase-shift channel optically coupled to the first optical splitter and configured to generate at least one frequency-shifted beam with an acousto-optic modulator (AOM) from the at least one portion of the incident beam received from the first optical splitter, and a second optical splitter configured to receive the at least one frequency-shifted beam from the at least one phase-shift channel and configured to direct the at least one frequency-shifted beam to an interferometer configured to acquire an interferogram of a sample with the at least one frequency-shifted beam.

In a method for determining optical properties by measuring intensities at a thin layer, light is directed into the thin layer and passes through a beam splitter, which directs a first part of the light onto the thin layer and a second part of the light onto a reference detector. Interference of the first part of the light in the thin layer is detected via a high-resolution detector and forwarded to an evaluating unit, which determines the reflection and/or transmission coefficients, which are correlated with the optical layer thickness through a comparison using at least one database stored in the evaluating unit. The optical layer thickness is obtained as a gray value modification by way of a gray scale value analysis and a conversion factor stored in the at least one data base. A corresponding device and intended uses of the method and device are also described.

A sample structure measuring device includes a light source, a path splitting portion configured to split light from the light source into light on a measurement path passing through a sample and light on a reference path, an optical path merging portion configured to merge the measurement path and the reference path, a photodetector having pixels and configured to detect incident light from the path merging portion and output phase data of the incident light, and a processor. A first region is a region where the sample is present and a second region is a region where the sample is not present. The processor divides the phase data into the first region and the second region, sets an initial estimated sample structure based on the first region, and optimizes the estimated sample structure using simulated light transmitted through the estimated sample structure and measurement light transmitted through the sample.

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 system can include a mirror that reflects incoming light to a sensor for detection. The position and/or orientation of the mirror can be controlled to reflect incoming light from different locations and/or directions. Position and/or orientation of the mirror may be tracked and/or detected by an optical position sensor. The position sensor can transmit a beam to a reflector on the mirror, and the reflected beam can be received by the position sensor. Characteristics of the reflected beam can be measured to determine the position and/or orientation of the mirror. For example, the beam can be used for interferometric and/or intensity measurements, which can then be correlated with a position and/or orientation of the mirror.

A three-dimensional measurement device includes: a light emitter; an optical system that splits an incident light, irradiates a measurement object with an object light and irradiates a reference plane with a reference light, and recombines the object and reference lights and emits a combined light; an imaging device that takes an image of a light emitted from the optical system; a storage device that stores transmission axis absolute angle data each obtained by a previous actual measurement of an absolute angle of a transmission axis of each polarizer; and a control device that calculates a phase difference between the reference and object lights based on luminance data of each pixel in luminance image data and the transmission axis absolute angle data of each polarizer corresponding to the pixel, and measures a height of the measurement object at the measurement position.

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.