Abstract: The invention relates to an interferometric method for measuring a height of a first region on a first surface, the first surface having first areas having first optical properties and second areas having second optical properties, the method comprising the steps of generating of first and second coherent light beams, reflecting at least the first coherent light beam from the first region into a first return beam and reflecting the second coherent light beam from a second region into a second return beam, measuring at least a first reflectivity of the first region, determining a topography-dependent phase shift of the first and second return beams for the height measurement based on the first reflectivity.

Abstract: A method for measuring a spectrum of a terahertz pulse includes generating a terahertz pulse using an ultrashort pulsed pumping light, generating a white light pulse using an ultrashort pulsed probe light, stretching and chirping the white light pulse modulating the chirped white light pulse such that the terahertz pulse and the chirped white light pulse irradiate into an electro-optic crystal synchronously, so that the chirped white light pulse is modulated by an electric field signal induced at the electro-optic crystal irradiated by the terahertz pulse, detecting a spectrum of chirped white light pulse modulated at the electro-optic modulating step by a multi-channeled detector, analyzing an electric field of the teraherz pulse irradiated to the electro-optic crystal from the spectrum of the chirped white light pulse detected by the multi-channeled spectrum detecting step, and transforming the analyzed electric field signal into a frequency spectrum of the terahertz pulse.

Abstract: A passive optical system substantially simultaneously separates light received at an optical input into three or more output light beams on optical outputs. The output light beams may have intensities that are proportional to intensities of optical projections of the received light onto three or more basis vectors of a tetrahedral basis set of a Stokes space. The system includes either multiple partial polarization splitters or multiple optical interferometers.

Abstract: A spectrometer for use with a desired wavelength range includes an array of filters. Each filter outputs at least two non-contiguous wavelength peaks within the desired wavelength range. The array of filters is spectrally diverse over the desired wavelength range, and each filter in the array of filters outputs a spectrum of a first resolution. An array of detectors has a detector for receiving an output of a corresponding filter. A processor receives signals from each detector, and outputs a reconstructed spectrum having a second resolution, the second resolution being higher than any of the first resolution of each filter.

Abstract: An interferometer spectrometer that has reduced alignment sensitivity is described herein. Parallelism of an output ray pair formed by a single input ray is not affected by variations in relative alignment of the components. In comparison to other compensated interferometer designs, lateral separation errors in the output ray pair due to optical component misalignment are reduced. The reduced alignment sensitivity may be accomplished by utilizing simple planar components that are common to both light paths. The reduced alignment sensitivity and simplicity in design provides a more compact and more robust interferometer, with reduced manufacturing costs associated therewith. An elliptical field of view light source that utilizes an array of collimator lenses is also described. The light source provides a more compact design than a single circular collimator lens of the same area, and is suitable for single channel or multi-channel use.

Abstract: An interferometry system including: a first imaging system that directs a measurement beam at an object to produce a return measurement beam from the object, that directs the return measurement beam onto an image plane, and that delivers a reference beam to the image plane; and a beam combining element in the image plane, said beam combining element comprising a first layer containing an array of sagittal slits and a second layer containing an array of tangential slits, wherein each slit of the array of sagittal slits is aligned with a corresponding different slit of the array of tangential slits, wherein the beam combining element combines the return measurement beam with the reference beam to produce an array of interference beams.

Abstract: A method and apparatus for performing optical microscopy in one to three dimensions employs a spectral self-interference fluorescent microscopy technique that includes providing at least one fluorescent microscopy sample, at least one objective lens, and at least one reflecting surface. The fluorescent sample is disposed between the objective lens and the reflecting surface, the distance from the sample to the reflecting surface being several to several tens times an excitation wavelength. Excitation light causes the fluorescent sample to emit light, at least a portion of which is reflected by the reflecting surface. The objective lens collects the reflected light and the light emitted directly by the fluorescent sample. The direct and reflected light interfere causing spectral oscillations in the emission spectrum. The periodicity and the peak wavelengths of the emission spectrum are spectroscopically analyzed to determine the optical path length between the fluorescent sample and the reflecting surface.

Abstract: For determining a signal response characteristic of a device, a first signal is varied with a first function of time and simultaneously a second signal is varied with a second function of time, wherein the first function is different from the second function. The first and second signals are coupled to the device, wherein the device is exposed to a time-dependent disturbance signal. A signal response is received from the device in response to the first and second signals and the time-dependent disturbance signal. The signal response characteristic is derived by analyzing the received signal response in conjunction with the first and second signals, or a signal derived therefrom, and at least partially removing the time-dependent disturbance signal using the received signal response and the first and second signals, or a signal derived therefrom.

Abstract: A surface inspection apparatus for inspecting a surface of an object to be inspected, includes: a projecting optical system which projects an inspection light to the object surface via a reference surface; a pick up unit which picks up surface interference fringes formed by reflected light from the reference surface and reflected light from the object surface; and an arithmetic unit which calculates a shape of the surface of the object based on the picked up interference fringes. The projecting optical system includes a laser light source that emits, as the inspection light, pulsed laser light having a pulse width and a pulse quiescent time capable of preventing formation of rear face interference fringes which are formed by the reflected light from the object surface and reflected light caused by the inspection light being reflected from its rear face, the object allowing the inspection light to pass therethrough.

Abstract: Methods and systems for static multimode multiplex spectroscopy are disclosed. According to a method for static multimode multiplex spectroscopy, spectral energy emanating from different points of a diffuse source is simultaneously received. Different multi-peak filter functions are applied to the spectral energy emanating from the different points to produce a multi-channel spectral measurement for each point. The multi-channel spectral measurements are combined to estimate a property of the diffuse source.

Abstract: A method and apparatus for correction of laser gyro dither pickoff signals. Dither pickoff signals are sampled during the dither input signal cycle at points where error is more prevalent in the dither pickoff signal. The samples are then used to modify correction factors used in the calculation of a corrected dither pickoff signal.

Abstract: Methods and devices are provided for determining the presence and/or concentration of at least one analyte in a sample of low transmissivity. In the subject methods, a forward beam and a backward beam are produced by or introduced into an interferometer from at least one infrared radiation source. The forward beam is passed into the sample and then collected to produce a sample beam while the backward beam is passed into a reference and then collected to provide a reference beam. The sample and reference beams are recombined either optically into a null beam which is detected at a single detector or electronically nulled after detection on two separate detectors. The presence, and often amount, of at least one analyte in the sample is then derived from the detected null beam. Also provided are devices for practicing the above methods.

Abstract: A fiber optic gyroscope includes a light source and a phase modulator coupled to an optical fiber coil. Light from the source is divided into a pair of first light signals that are directed into opposite ends of the coil to counter propagate through the coil and produce corresponding second light signals the relative phases of which are shifted by the modulator. In one embodiment, a waveform generator defines a modulation waveform so that a determined sequence of five or more phase shifts are set between the second light signals, including shifts of zero degrees, +90 degrees, ?90 degrees, +180 degrees and ?180 degrees. The second light signals interfere with one another to define a recombined light signal, and measurement signals corresponding to the intensity of the recombined light signal are obtained for each phase shift in the sequence. A rate of rotation of the coil is determined continuously in accordance with the measurement signals and a given interference function.

Abstract: In optical coherence tomography (OCT), Axial and lateral resolutions are determined by the source coherence length and numerical aperture of the sampling lens, respectively. While axial resolution can be improved using a broadband light source, there is a trade-off between lateral resolution and focusing depth when conventional optical elements are used. The incorporation of an axicon lens into the sample arm of the interferometer overcomes this limitation. Using an axicon lens with a top angle of 160 degrees, 10 ?m or better-lateral resolution is maintained over a focusing depth of at least 6 mm. In addition to high lateral resolution, the focusing spot intensity is approximately constant over a greater depth range.

Abstract: A phase-diverse coherent optical spectrum analyzer is presented. An optical receiver receives a first input signal and a second input signal, and produces at least a first output signal, a second output signal, and a third output signal based on mixing the first input signal and the second input signal. A processing unit isolates heterodyne components from the first output signal, the second output signal and the third output signal, wherein the heterodyne components comprise a first signal and a second signal that represent the phase-diverse nature of the optical mixing process. Phase diversity of the heterodyning between the first input signal and the second input signal is achieved by the coherent optical spectrum analyzer.

Abstract: The present invention relates to microinterferometers and the application of such to profile surface geometries. A representative method for profiling a target surface of an object includes: illuminating the target surface with an incident light beam through a phase-sensitive, reflective diffraction grating, such that a first portion of the incident light beam is reflected and a second portion of the incident light beam is diffracted upon being transmitted through the diffraction grating; receiving interference patterns produced from the first portion of he incident light beam reflected from the diffraction grating interfering with the second portion of the incident light beam reflected from the target surface; measuring the intensity of the interference patterns to determine the distance to determine the distance between a reference point and the surface; varying the position of the object relative to the diffraction grating; and processing the measured distances to profile the surface of the object.

Abstract: A method including: generating a sequence of phase-shifted interferometry images of an object surface relative to a reference surface; and calculating an unequally weighted average of the phase-shifted interferometry images to produce a final image. The final image can be useful as a lateral metrology image. The method may further include calculating a surface topography image from the sequence of phase-shifted interferometry images. Embodiments further include apparatus related to the method.

Abstract: An optical phase standard includes a coupler dividing an applied optical signal between a measurement interferometer and a frequency reference branch. Resulting signals at the outputs of the measurement interferometer and the frequency reference branch are sampled. The samples acquired at the output of the frequency reference branch are mapped to optical frequencies that are traceable to a frequency standard provided by an absorption cell. This mapping determines the optical frequencies at which the samples acquired are at the output of the measurement interferometer. From the acquired samples at the output of the measurement interferometer, phase characteristics of a device under test (DUT) are extracted. Aspects of the optical phase standard are alternatively implemented according to an optical phase standardization method.

Abstract: A fundamental concept of the invention consists thus in the fact that temporally variable reference and object light bundles are generated for object detection, the bundles are superimposed at a light receiver and detected beam by beam and the penetration of the object by selected beams is determined in response to the temporal variability of the superimposed beams.

Abstract: An interference spectroscopy instrument provides simultaneous measurement of specular scattering over multiple wavelengths and angles. The spectroscopy instrument includes an interference microscope illuminated by Koehler illumination and a video camera located to image the back focal plane of the microscope's objective lens while the path-length difference is varied between the reference and object paths. Multichannel Fourier analysis transforms the resultant intensity information into specular reflectivity data as a function of wavelength. This multitude of measured data provides a more sensitive scatterometry tool having superior performance in the measurement of small patterns on semiconductor devices and in measuring overlay on such devices.