Abstract: A time resolved, nonlinear complex susceptibility measuring apparatus (1) that is capable of measurement unaffected by any distortion of the wave front of a probe light whereby a temporal change in the nonlinear complex susceptibility of a nonlinear optical material that occurs when it is irradiated with a light pulse in a femtosecond range is measured using a pair of polarized lights orthogonal to each other which are formed by splitting a single light pulse into a reference and a probe light (5) and (6) in a polarized light splitting Sagnac type interference light path (8). A direction of polarization converting mechanism for rotating a direction of polarization of the reference and probe lights by an angle of 90° in the polarized light splitting Sagnac type interference light path is included to align the directions of polarization on a test specimen (3).

Abstract: In one embodiment, a method determines the spectral content of an optical signal. Specifically, the optical signal and an optical local oscillator (LO) signal are provided to inputs of an optical hybrid (e.g., an N×N optical coupler where N is greater than two). The phase-diverse components from the optical hybrid are photodetected allowing for mixing of the optical signal and the optical local oscillator. Bandpass filtering is performed to eliminate or reduce relative intensity noise (RIN). The filtered signals are mixed with an electrical LO signal. A quadrature representation of a phase-diverse heterodyne signal is generated from signals from the mixing. The negative image and the positive image from the quadrature representation are separated. The spectral content of the optical signal is determined from the images.

Abstract: This invention provides a device or method for measuring vibration with high sensitivity and over a wide bandwidth. A curved section is formed in an optical fiber. The curved section is disposed on a place to be measured. Light is input in the optical fiber, and then variation of frequency between the input light and the output light is detected. Infinitesimal vibration applied to the curved section can be measured as variation of frequency between the input light and the output light. Further, it is possible to measure vibration over a wide bandwidth.

Abstract: A laser ultrasonic inspection apparatus and method which enables remote sensing of thickness, hardness, temperature and/or internal defect detection is disclosed. A laser generator impinges a workpiece with light for generating a thermo-elastic acoustic reaction in a workpiece. A probe laser impinges the workpiece with an annularly-shaped probe light for interaction with the acoustic signal in the workpiece resulting in a modulated return beam. A photodetector having a sensitive region for detecting an annularly-shaped fringe pattern generated by an interaction of a reference signal and with the modulated return beam at said sensitive region.

Abstract: A semiconductor fabricating apparatus for etching a semiconductor wafer, which is placed in a chamber and which has a multiple-layer film composed of a first film formed on a surface thereof and a second film formed on the first film, using plasma generated in the chamber. The semiconductor fabricating apparatus includes a light detector that detects a change in an amount of light with a plurality of wavelengths obtained from the surface of the wafer for a predetermined time during which the second film is etched, and a detection unit that detects a thickness of the first film based on a specific waveform obtained from an output of the detector.

Abstract: Process control monitors are disclosed that are produced using at least some of the same process steps used to manufacture a MEMS device. Analysis of the process control monitors can provide information regarding properties of the MEMS device and components or sub-components in the device. This information can be used to identify errors in processing or to optimize the MEMS device. In some embodiments, analysis of the process control monitors may utilize optical measurements.

Abstract: The invention is an apparatus and method for second harmonic optical coherence tomography of a sample comprising a laser coupled to an interferometer which has a reference arm and in a sample arm. A nonlinear crystal in the reference arm generates a second harmonic reference signal. The sample typically backscatters some second harmonic light into the sample arm. A broadband beam splitter optically coupled to the reference arm and sample arm combines the signals from the reference arm and sample arm into interference fringes and a dichroic beam splitter splits the interference fringes into a fundamental and second harmonic interference signal. A detector is optically coupled to the dichroic beam splitter detects interference fringes from which both an OCT and second harmonic OCT image can be constructed using a conventional data processor.

Abstract: An apparatus and method for controlling a laser system is disclosed which may comprise a spectrometer adapted to measure an unknown bandwidth of a spectrum of light emitted from the laser, which may comprise an optical bandwidth measuring unit adapted to provide as an output a measured parameter, which is indicative of a parameter of the unknown bandwidth of the spectrum being measured; a reported parameter computing unit adapted to compute a reported parameter of the unknown bandwidth of the spectrum being measured according to the formula: Reported Parameter(“RP”)=A*(Measured Parameter(“MP”))+C, wherein the RP and MP are a different type of parameter and the values of A and C are determined based upon calibration of the optical bandwidth measuring unit MP response for light of known valued of RP.

Abstract: A method for the rapid measurement of polarization dependent properties of an optical device under test uses a novel technique to generate light in four different polarization states in which each state is individually sensed at a different interference frequency. The device for executing this method includes a Mach-Zehnder interferometer (M-Z) having a reference arm and a signal arm. In the signal arm, a device called a “polarization state frequency multiplexer” (PSFM) splits the light into four ports, transforms each part into one of four predetermined polarization states and then combines the light in the different polarization states together. The combined light is then passed through the device under test and combined/interfered with the light propagating through the reference arm at the output of the M-Z interferometer.

Abstract: Provided is an optical image measuring apparatus capable of easily changing a scanning interval of an object to be measured in a depth direction with high precision.

Abstract: A sample inclination measuring method rotates, by a predetermined angle with respect to an interferometer apparatus, a columnar member having a leading end face in a planar form while the columnar member is held by a clamping apparatus, detects a relative angle between a reference surface of the interferometer apparatus and the leading end face at each of two rotational positions, and measures the inclination of the axis of the columnar member by using a predetermined arithmetic expression according to thus detected two angles.

Abstract: An optical detection system according to the present invention includes: a spatial light modulator for modulating the phase of incoming light; a photodetector having a plurality of photosensitive areas to receive the light of which the phase has been modulated by the spatial light modulator; a photosensor selecting section for selecting at least one of the photosensitive areas and activating the selected photosensitive area effectively; and a modulation control section for providing a modulation pattern, associated with the photosensitive area that has been selected by the photosensor selecting section, for the spatial light modulator.

Abstract: An apparatus for measuring at least one parameter associated with a fluid flowing within a pipe comprises an optical measurement device and a signal processor. The optical measurement device provides output signals indicative of unsteady pressures within the fluid at two or more axial locations along the pipe in response to light reflected from an outer surface of the pipe. The signal processor provides an output signal indicative of at least one parameter associated with the fluid in response to the output signals. The optical measurement device may include, for example, an electronic speckle pattern interferometer, a Fabry-Perot device, and/or a laser vibrometer. The at least one parameter may include at least one of: density of the fluid, volumetric flow rate of the fluid, mass flow rate of the fluid, composition of the fluid, entrained air in the fluid, consistency of the fluid, size of particles in the fluid, and health of a device causing the unsteady pressures to be generated in the pipe.

Abstract: A method of detecting contaminants on a window surface of a viewing system comprises the steps of: reflecting light off of contaminants on the window surface; capturing the reflected light in an image; converting the image into image data; and processing the image data to detect the contaminants on the window surface. Also, apparatus for detecting contaminants on an external surface of a window of a viewing system comprises: at least one light source for reflecting light from contaminants on the external surface; an imager for capturing an image of the reflected light and converting the image into image data; and a processor for processing the image data to detect the contaminants on the external surface.

Abstract: Characterization of an optical system is quickly and easily obtained in a single acquisition step by obtaining image data within a volume of image space. A reticle and image plane are positioned obliquely with respect to each other such that a reticle having a plurality of feature sets thereon, including periodic patterns or gratings, is imaged in a volume of space, including the depth of focus. Metrology tools are used to analyze the detected or recorded image in the volume of space through the depth of focus in a single step or exposure to determine the imaging characteristics of an optical system. Focus, field curvature, astigmatism, spherical, coma, and/or focal plane deviations can be determined. The present invention is particularly applicable to semiconductor manufacturing and photolithographic techniques used therein, and is able to quickly characterize an optical system in a single exposure with dramatically increased data quality and continuous coverage of the full parameter space.

Abstract: Thermal expansion characteristics of test materials of ultra-low thermal expansion material are measured with a test beam that is split into a test material-measuring portion and an instrument-measuring portion. Both measuring portions propagate through common portions of a test arm. The test material-measuring portion encounters a test material, but the instrument-measuring portion does not. Thermal expansion characteristics of the test material are measured to high accuracy by manipulating the measures to distinguish displacements associated with the test material from displacements associated with the instrument structure.

Abstract: Apparatus for measuring polarization mode dispersion (PMD) of a device, e.g. a waveguide, comprises a broadband light source (10,12) for passing polarized broadband light through the device (14), an interferometer (20) for dividing and recombining light that has passed through the device to form interferograms, a polarization separator (30) for receiving the light from the interferometer and separating such received light along first and second orthogonal Feb. 25, 2003 Feb.

Abstract: Methods and apparatus for en-face imaging using multiple wavelengths are described. In general, an imaging system receives light reflected from a sample under test and distinguishes between reflected light at a first wavelength and reflected light at a second wavelength. Images at both wavelengths are collected simultaneously. En-face images are output using en-face image data corresponding to the first wavelength and en-face image data corresponding to the second wavelength.

Abstract: A system for aligning of optical components includes an interferometer and a first diffractive alignment element. A housing is used for positioning a first optical element being aligned. A detector is used for detecting fringes produced by reflections off surfaces of the first optical element. A grating pattern on the first diffractive alignment element is designed to produce a retro-reflected wavefront or a wavefront transmitted or reflected in a predetermined direction when the first optical element is in alignment. The first diffractive alignment element includes a first region for alignment of the interferometer, a second region for alignment of one surface of the first optical element, and a third region for alignment of another surface of the first optical element. The first, second and third regions can be of any shape such as circular, rectangular, triangular, or the like.

Abstract: A multi-axis plane mirror interferometer uses shared measurement and reference beams that respectively reflect from measurement and reference reflectors before that shared beams are split into individual beams corresponding to the measurement axes of the interferometer. An N-axis interferometer thus requires only N+1 measurement beam paths, one for the shared measurement beam and N for individual measurement beams, to provide for each measurement axis the two reflections that cancel angular misalignment between the measurement and reference reflectors.