Abstract: An interferometric gas component measurement apparatus has a light source (27), a measurement path (30) which contains the gas components to be measured, a polarizer (11), a double refracting plate arranged with its optical axis at 45.degree. to the polarization direction, two doubly refracting plates (14, 20) arranged with their optical axes at 45.degree. to one another and an analyzer (13). The light which passes through the measurement path is concentrated into an output gap (32) and reflected via a holographic concave grid (33) onto a diode row (22). The thickness of the individual plates is so selected that specific linear combinations of the thicknesses result in phase displacements between the beams polarized perpendicular to one another in the plates, with these phase displacements corresponding to the reciprocal of the quasi-periodic line splitting of selected vibration and/or rotation bands of the gas molecules of the gas components to be measured.

Abstract: A polarimeter for measuring the rotation of optically active samples comprises a light source which generates a measuring light beam, a polarizer mounted for rotation about the beam axis of the measuring light beam, a driving mechanism for reciprocating rotational movement of the polarizer, a sample vessel, an analyzer behind the sample vessel, a photoelectric detector, and balancing means which are controlled by the signal of the photoelectric detector and by which a position can be achieved in which the polarizer and analyzer are arranged substantially crosswise. The balancing means comprises a steeper motor for rotating the polarizer with an adjusting movement superimposed by the reciprocatingly rotational movement by which adjusting movement a quick coarse balancing of the polarizer plane of the measuring light beam relative to a zero position of the analyzer is achieved.

Abstract: A method of determining physical characteristics of a surface. Light or other electromagnetic radiation is directed onto a first portion of a surface and the reflected radiation is received such as by a photodiode. The radiation is also directed onto at least two further portions of the surface and located on either side of the proximate to the first portion. The radiation reflected by the further portions is also received. The radiation reflected from the first portion is compared with the radiation reflected from the two further portions. The radiation and comparison steps are repeated and the comparisons are used to determine a physical characteristic of the surface, such as the presence of one or more flaws. In another embodiment, light or other electromagnetic radiation is used to determine object dimension, such as bore dimension.

Abstract: The invention is directed to a method for testing optical components and tests can be made on aspherical surfaces or, more specifically, on aspherical wavefronts. For this purpose, the collimator of an interferometer which generates the test wave is displaced relative to the test component and interferograms are electronically registered by means of an image sensor in different positions of the collimator and are stored as light path length differences between the test beam and the comparison beam for the individual image points of each interferogram. The relative position between the collimator and the test component is additionally measured with high precision. Thereafter, the light path length differences which were measured interferometrically are compared with desired light path length differences computed for the different positions of the collimator or determined by calibration. From this comparison, the aspheric form of the wavefront of the test component is computed.

Abstract: A device for measuring a moving distance of two relatively moving objects includes a first diffraction grating provided on one of the two objects and disposed along the relatively moving direction of the two objects, and a measuring portion provided on the other object. The measuring portion includes a second diffraction grating, a light source and a photodetecting system, wherein the light source provides lights which are projected upon two points on the second diffraction grating so that they emanate from the two points in the form of diffraction lights having different diffraction orders. The diffraction lights are directed to the same point on the first diffraction grating and are diffracted again by the first diffraction grating so that they are emitted in the same direction, and the photodetecting system is operable to detect a change in the light intensity caused due to the interference of the two lights emanating from the first diffraction grating.

Abstract: A light-reflection defect detection apparatus and method for sensing the presence of food products or other articles and detecting defects therein is described using pulsed light-emitting semiconductor devices, such as light-emitting diodes (LEDs). The LEDs emit at least three different wavelengths of light including two of visible light (i.e., red and green light) and one of infrared light. Viewers each including photosensor, such as a photoelectric detector, are employed to sense the light reflected from the article and to produce sensor output signals which are sampled and stored before being transmitted to a digital computer for signal processing. The groups of LEDs are pulsed ON and OFF by a capacitor discharge pulse generator circuit which causes a substantially constant current to flow through the LEDs so that they emit light of uniform intensity. The defect detection apparatus and method is especially useful in detecting defects in elongated food products such as French-fry potato strips.

Abstract: A two-dimensional position detecting method detects a two-dimensional position of an object which has a diffraction grating provided thereon, and this diffraction grating comprises a first grating portion which extends in a first direction and a second grating portion which extends in a second direction which is perpendicular to the first direction.

Abstract: Interferometric equipment for detecting a substance having a structure preferably a periodic or quasiperiodic absorption spectrum; the equipment includes a source of radiation, a path for that radiation that includes a sample cell with the substance to be detected, an interference filter and a detector, and is improved in that the interference filter is constructed as an electrically tunable filter, including a plate or cell element with semitransparent reflective boundaries serving as electrodes; an electrical voltage is applied to said electrodes such that the transmission characteristics of the filter is varied and the amplitude of the voltage as applied to these electrodes is an indication of that variation; and the thickness of the plate or cell is selected to meet one of the following criteria (i) a distance between the interference lines produced equals a distance of absorption lines within a periodic absorption spectrum of said substance; (ii) the equipment causes a line to be separated from the radia

Abstract: The surface profile measuring device utilizing optical heterodyne interference comprising a laser source for emitting a laser beam, an object lens for converging the laser beam on the surface of an object to be measured, the laser beam being reflected from the surface of the object while provided with information on a surface profile of the object, an optical heterodyne interference device for allowing the reflected beam to interfere with a reference beam having a frequency different from that of the reflected beam to generate beat signals having the information on the surface profile of the object, a circuit for measuring the surface profile of the object on the basis of phase variation of the beat signals, a driving device including a piezoelectric element for relatively moving one of the object lens and the object to be measured in the direction of the optical axis of the laser beam incident on the surface, and a control device for controlling the driving device on the basis of the phase difference or ampl

Abstract: This invention discloses a high-precision alignment system for aligning a mask with a wafer in a high-resolution microlithography system. This alignment system has a high-sensitivity mask-wafer displacement detection system characterized by an optical heterodyne technique that uses two laser frequencies to generate by diffraction and interference a displacement signal at a different frequency, and has a high-precision mask-wafer positioning system that uses a laser modulation spectroscopic technique characterized by controlling the cavity spacing of a highly stable optical resonator with a modulated frequency-stabilized laser, making it possible to align a wafer pattern with a mask pattern with a precision on the order of a few nanometers.

Abstract: An interferometer modulator (10) has a housing (12) that encloses a moving mirror (14) attached to a mirror arm (18) which is suspended by links (34, 36) from the housing (12). The links (34, 36) are attached to the mirror arm (18) at swinging pivots (42, 44) and are attached to the housing (12) at fixed pivots (46, 48). One of the fixed pivots (46) is mounted within an adjustable block (68) the position of which may be adjusted by the turning of adjust screws (82, 76). Turning of one of the adjust screws (82) adjusts the distance between the fixed pivots (46, 48) to match the distance of the swinging pivots (42, 44), thus correcting for vertical tilt. Turning of the second of the adjust screws (76) compensates for any angular differences that would prevent the links (34, 36) from moving in the same plane of motion, thus correcting for horizontal tilt.

Abstract: In semiconductor processing, it is desirable to protectively cover the wafer (40) prior to sawing the wafer (40) into individual chips. The compressive nitride protective cover tends to bow the normally flat surface of the wafer (40). If the compressive stress is too great, the wafer (40) and the circuits thereon may be damaged. The laser stress measurement apparatus (10) provides a method for checking the wafer (40) for excess stress without destroying the wafer (40). A light source (12) emits a beam of light onto a reflector (22) which reflects the light onto wafer (40). The light is deflected by wafer (40) back to the reflector (22) and thence to a light detector (52). The light detector (52) is positioned to receive the light in an exact center such that subsequent readings may be taken to determine a change in deflection. The change in deflection is then used in a formula to determine the compressive stress on wafer (40).

Abstract: A wavelength-independent-interferometer comprises means to receive light (10) from a field of view, means (BS1) to separate the light into two beams (11, 12), means (BS2) to combine the two beams, and dispersive means (30) interposed in the path (12) of one of the two beams to produce a wavelength-dependent shear. The dispersive means may be a transmission diffraction grating or a reflection grating. In the arrangement shown the optical elements are combined in a modified Mach-Zehnder interferometer. When the conventional Mach-Zehnder interferometer is illuminated with coherent light the separation of interference fringes produced in the interference plane is inversely proportional to the wavelength. By introducing a dispersive element in the invention the detector is sensitized to a pre-determined fringe separation. A moveable reticle is placed in front of a detector to sensitize the detector to the fringe pattern.

Abstract: A borescope apparatus having a borescope and a pressurized fluid supply device. The borescope has an operation unit and an insertion unit. The insertion unit comprises a bending tube portion, a jet port member coupled to a proximal end of the bending tube portion, and a flexible tube portion. The bending tube portion can be bent by operating the operation unit. The jet port member has a jet port. A pressuring fluid is supplied from the fluid supply unit to the jet port member, and is ejected through the jet port. The flexible tube portion can be bent by a jet of the fluid from through the jet port independently of the bending tube portion.

Abstract: In an opto-electronic sight, including several optical devices, the separate optical axes are combined by means of mirrors and beam splitters so that all the beam paths amay be directed exactly at the same sight point, either directly or via a directing and stabilizating mirror. Axis alignment errors and the need for axis adjustment are eliminated.

Abstract: An adaptor for holding a micropipette in a spectrophotometer includes a base member for holding the micropipette and an optical system for linearly focusing visible or ultraviolet light onto the micropipette. Specifically, the optical system includes a cylindrical lens which focuses collimated light from a light source into a line along the axis of the micropipette. The optical system also includes a cylindrical quartz lens which recollimates the light that has passed through the micropipette sample holder. A detector is provided to receive the recollimated light for measuring the absorptivity of the sample material held in the micropipette.

Abstract: A micro-flow cell for chromatographic, spectrometric or scintillation measurements comprises a capillary tube, preferably made of glass or silica glass, through which flows the medium to be examined, and a holding device for said capillary tube. The holding device is separably composed of at least two parts which can be separated in their longitudinal direction. The capillary tube is fixed in the holding device by suitably formed connectors so as to be stress-free and tension-free to the greatest possible extent.

Abstract: A first diffraction grating is formed on a mask, and a second diffraction grating is formed on a wafer. Two light beams having slightly different frequencies interfere with each other and are diffracted as they travel through the first diffraction grating, are reflected by the second diffraction grating, and again pass through the first diffraction grating. As a result, they change into thrice diffracted light beams. The diffracted light beams are combined into a detection light beam which has a phase shift .phi..sub.A representing the displacement between the wafer and the mask, or a phase shift .phi..sub.G representing the gap between the wafer and the mask. The detection light beam is converted into a detection signal. The phase difference between the detection signal and a reference signal having no phase shifts are calculated, thus determining phase shift .phi..sub.A or .phi..sub.G. The displacement or the gap is determined from the phase shift.

Abstract: The concentration of optically active substances is determined by measuring the polarization of light passed through the substance using a light source, a polarizer and a modulator operated at a predetermined modulation frequency f.sub.F, as well as a measuring cell, an analyzer and a detector. The output signal from the detector 16 is alternately integrated during each half period of the modulation frequency to form voltage values U.sub.I+ and U.sub.I-. These voltage values are stored and the quotient Q of these stored voltage values is formed. Subsequently, an adjustable constant voltage is subtracted from the quotient. The measuring arrangement can have a miniature design for implantation. No mechanically moving parts and only a single detector are used. The measurement is accomplished by a simple, miniature linear ray path having high resolution.

Abstract: An apparatus for measuring a very small difference comprises a stage for receiving a sample to be measured, a light source illuminating the sample, an optical system for condensing light reflected from the sample, structure for intercepting a portion of the reflected light, a spectroscope for analyzing the condensed reflected light and a detector for detecting spectrum of the analyzed light. Light reflected only from a main surface of the sample is intercepted by the intercepting structure. Thus, the signal to noise ratio of the reflected light is reduced to enhance measurement capability.