Abstract: A method and apparatus are provided that indicate the amount of gas such as air in a clear liquid such as water. The apparatus includes a transparent pipe (60), an input coupling (16) at a first end of the transparent pipe, and a shutoff valve (20) at the second end of the pipe. The first end of the pipe is connected to a source of water (12) under pressure, whose air content is to be determined. With the valve (20) open, water is allowed to pass through the pipe and valve to purge the pipe of air and any previous water. The shutoff valve is then closed, to contain the water under pressure. The dissolved air in the static, pressurized water, immediately forms microscopic air bubbles, which result in the water having a "milky" appearance. The presence of the milky appearance indicates the presence of a considerable amount of dissolved water (when the water is not under high pressure). The reflectivity of the water indicates the amount of dissolved air per unit volume of water (when not under high pressure).

Abstract: An apparatus for detecting a target substance in a pixel array is provided. The apparatus has a light source to emit a light suitable for exciting the target substance in the array, a total internal reflection (TIR) member, and a light detector. The TIR member has a TIR surface on which the array is located. The light from the light source passes into the TIR member and is reflected by the TIR surface. The array is within an evanescent field region at the TIR surface. The light detector is adapted to detect light emitted from the array as a result of evanescent excitation of the target substance.

Abstract: A system for evaluating a distribution of an absorption light amount in a resist comprises a diffractive light intensity distribution calculating unit for calculating a diffractive light intensity distribution on a plane of a pupil of a projection exposing apparatus, a light absorption rate calculating unit for calculating, on the basis of an incidence angle and a thin-film interference effect of each of diffractive light intensity components of the diffractive light intensity distribution passing through the pupil and being incident on a wafer surface of the projection exposing apparatus, a light absorption rate of each of the diffractive light intensity components in a resist of the projection exposing apparatus, a weight calculating unit for calculating a weight of each diffractive light intensity component, on the basis of the light absorption rate of each diffractive light intensity component calculated by the light absorption rate calculating unit, a multiplying unit for multiplying each diffractive lig

Abstract: The apparatus measure the radius of curvature of a reflective or partially reflective surface 18, and comprises first and second lasers 2, 4 which generate two parallel beams a known distance apart. A lens 12 focuses the beams, which are passed via a beam splitter 14 and transform lens 16 to the surface 18. The beams are reflected back via the transform lens 16 and the beam splitter 14 onto a detector 20. A processor 22 calculates the radius of curvature of the surface in dependence of the known distance X separating the beams and the positions of the beams on the detector 20.

Abstract: A broad-bandwidth interferometric system that produces irradiance signals at multiple vertical-scanning positions as a function of optical path differences between a test and a reference surface. The effective peak of the envelope defined by the modulation component of the irradiance signal is estimated by finding the scanning position corresponding to the centroid of a function substantially equal to the square of the first-order derivative of the measured irradiance. The surface height at each pixel is determined directly from digital irradiance signals, thereby greatly reducing the data-processing steps and associated costs taught by the prior art and correspondingly simplifying the hardware requirements of the system for rapid on-line display of height measurements. The approach is free of the ambiguities inherent in multi-peak modulation functions, thereby producing surface maps with reduced artifacts.

Abstract: A distance measurement system employs a monochromatic coherent light source which produces an outgoing ray which impinges upon a target reflector which reflects the beam back as a reflected beam to an interferometry detector. A portion of the outgoing ray also is delivered to the interferometry detector. As the target reflector position is changed, the interferometry detector continuously calculates changes in distance of the target reflector. The orientation angles of the target reflector are constantly and automatically adjusted so that the reflected light beam accurately strikes the interferometry detector. A misalignment detector senses the elevation offset and the azimuth offset of the target reflector and creates corresponding signals.

Abstract: A propagation delay time measuring device has a test signal generating circuit, a time measuring circuit, a data table and a calculation circuit. The test signal generating circuit generates a test signal and supplies the test signal to a measuring point which is connected to one of the terminals of a signal transmission line. The time measuring circuit receives a signal waveform at the measuring point. The signal waveforms indicates an waveform of the test signal supplied to one of the terminals of the signal transmission line and a waveform reflected by another terminal of the signal transmission line and returned to the measuring point. The time measuring circuit measures a time when the test signal is supplied to the measuring point and a time when the reflected waveform is returned to the measuring point based on the signal waveform at the measuring point.

Abstract: When a stage moves, the position of the stage is detected by an interferometer, and a control unit controls the position of the stage while monitoring the output of the interferometer. Thus, the control unit effects positioning of the stage. In addition, the control unit calculates the square root of an arithmetic mean of the square of an error between target and present positions of the stage on the basis of the output of the interferometer, and estimates an amount of vibration of the stage on the basis of the result of the calculation, thereby enabling vibration characteristics to be quantitatively evaluated to a certain extent when the damping of vibration is rapid immediately after positioning, or when the damping is gentle or almost zero.

Abstract: A method and resulting system for directing generally collimated illumination from a source at an oblique angle to a surface under inspection (SUS) to produce scattered nonspecular energy substantially normal to the SUS and for observing the scattered nonspecular energy in one of a plurality of fractional windows of a viewed image of the SUS via a plurality of focussing elements. Such arrangement results in simultaneous and significant throughput and sensitivity enhancement over existing art. The method can be enhanced further wherein the observing step is performed through suitable relative motion of the scattering image over the imaging plane to permit over sampling. Furthermore, the DMT is significantly simplified because imaging is utilized to electronically scan the wafer instead of using opto-mechanical scanning means. Imaging sensors with an aggregate 2000.times.2000 pixel resolution could image a 200 mm wafer to 100 microns pitch.

Abstract: An absolute measuring interferometer having a measuring interferometer, a tunable laser emitting a laser beam and a control interferometer for adjusting the air wavelength of the laser beam. The control interferometer adjusts the air wavelength of the laser beam to a specific wavelength value at the ends of each measuring cycle. The wavelength of the tunable laser is continually tuned within the specific wavelength interval where the phase change of the interference signal is continually detected during the wavelength modulation process. An absolute measurement is determined by a simple mathematical relationship between the measured wavelength and phase changes.

Abstract: This invention is a method for remotely obtaining roadway crown point elevation and horizontal location based on projecting a horizontal laser beam configured vertically in either a continuous or discrete manner across the roadway surface at a predetermined elevation substantially coincident with the crown point of the roadway. The highest elevation of the roadway partially occludes the vertically configured laser beam. The lowest elevation of the laser beam which contacts an array of vertically configured laser receivers positioned on the opposite side of the roadway is by necessity the elevation of the roadway crown. By using an optical detector at a known vertical offset from the laser beam emitter, the angle and hence the distance can be determined to the furthest laser impact with the roadway. This distance information can be combined with the known line between the laser emitter and laser receivers to resolve the horizontal coordinates of that point.

Abstract: A laser strainmeter has a plurality of sensor resonators, each comprising a multiple reflection interferometer having a pair of concave mirrors (8) which are secured to the inner wall of a container (1) to face each other in the diametrical direction of the container so that the optical axes of the sensor resonators extend in different directions. The laser strainmeter further has a reference resonator comprising a multiple reflection interferometer having a pair of concave mirrors (12) which are disposed in the vicinity of the sensor resonators, and which are held at a fixed distance. Laser light having the same resonance frequencies as those of the associated resonators are transmitted from laser oscillators to the resonators through optical fibers (3).

Abstract: A method of visually aligning an optical instrument (10, 26, 28) that simultaneously operates at two different wavelengths where the first wavelength is in the visible photopic electromagnetic spectral region and the second wavelength is outside the visible photopic electromagnetic spectral region. The method for visually aligning the optical instrument (10, 26, 28) includes employing an aiming reticle (12) located at the eyepiece (18) of the optical instrument (10, 26, 28), this first reticle (12) having a reticle pattern (64) which is in focus when viewed through the eyepiece (18), and a plate (44) with a second reticle pattern (62) on one side. The second reticle pattern (62) is positioned in the optical system such that when this second reticle pattern (62) is illuminated (58) with light of the first wavelength, then this second reticle pattern (62) will be in focus and superimposed on the first reticle pattern (64) when viewed through the eyepiece (18).

Abstract: There is provided a method and an apparatus for testing an optical component for cosmetic defects, the component having optical surfaces, a peripheral surface and a bulk defined by the optical and peripheral surfaces, a range of inspection of the component including at least one optical surface and the bulk of the component at least in the vicinity of the one optical surface. The method includes producing at least one beam of inspection radiation and directing rays of the at least one beam onto the peripheral surface at such angles as to enable the rays to travel in the bulk of the component by multiple total internal reflections from the at least one optical surface, providing illumination of each point in the inspection range by set of rays at different angles, and to emerge from the component through the peripheral surface, and monitoring a radiation scattered by the defects and emerging from the component through the at least one optical surface, thereby identifying the defects.

Abstract: A system and method of passive detection of a luminous target employs a prior knowledge and a present measurement of its electromagnetic spectrum during a target acquisition procedure and, subsequently, during analysis of the spectrum to determine the presence of Doppler shift and broadening of lines of the spectrum. The prior known reference spectrum is adjusted for the Doppler shift so as to enable identification of the corresponding spectral lines of the received target spectrum. A history of the spectral data enables an identification of the type of target, as in the case of a rocket, and a determination of characteristics of a flight of the rocket.

Abstract: An apparatus for performing non-contact measurement of relative displacement includes a microscope having one objective lens and two fields of view in which two points of measurement on a test piece can be located separately, a pair of cameras for taking images obtained with the microscope, and an apparatus for measuring the relative displacement of the images of the two points of measurement obtained by the cameras.

Abstract: A method for imaging objects in turbid media. According to one embodiment of the invention, the method comprises the steps of (a) illuminating the object through the turbid medium with a pulse of light, the light emergent from the turbid medium consisting of a ballistic component, a snake-like component and a diffusive component, the diffusive component including Fermat photons and non-Fermat photons; (b) gating the light emergent from the turbid medium to preferentially select Fermat photons; and (c) forming an image of the object using the gated light. Preferably, a spatial gate is used to preferentially select Fermat photons from the emergent light. This may be done by orienting the source of the illuminating light and a light detector to lie along a most favorable path travelled predominately by Fermat photons. A time gate, such as a streak camera or the like, may be used in addition to the spatial gate to more carefully select Fermat photons from the emergent light.

Abstract: A diffuse reflectance probe is disclosed which employs in an exemplary embodiment, fiberoptic light transmitting elements and a light pipe for collecting light. The fiberoptic light transmitting elements surround the light pipe and a window having a beveled surface communicates with the light transmitting fiberoptics to direct illuminating radiation in a relatively large field of view in a close working distance with the probe.

Abstract: A substrate having a photonic device mounted thereon with a working portion that is operably connected to at least one electrical lead. A molded optical portion having a surface for light signal to enter and to exit is formed that encapsulates the substrate, the photonic device, and a portion of the first and second electrical lead. An optical connector is formed to plug into the molded optical portion to connect a fiber bundle thereto and the optical portion is electrically connected to an interconnect module.

Abstract: A small package voltage reduction system which is especially adapted for easy installation into a conventional high intensity discharge light, such as a street light having a receptacle for receiving a standard ambient light sensor. The invention permits extremely easy and thus inexpensive installation and maintenance and yet provides a significant reduction in energy use which may save significant expenditure for energy by a municipality or other user of high intensity discharge lights.