Abstract: A photo-electric conversion device is provided with an independent optical system having a lens making an image of the surface of an object to be inspected which is not flat as a flat spatial image at the front stage of the photo-electric conversion device. The photo-electric conversion device receiving the flat spatial image on its target screen produces a video signal. An inspection device for processing an output video signal is provided to judge whether the inspected surface is good or not.

Abstract: In a particle detector, a stream entraining particles to be measured is passed through a laser beam. Light scattered in two different directions from the laser beam by particles are detected by photodetectors and a coincidence circuit detects simultaneous pulses generated by both photodetectors to discriminate against noise and to disable the integration function in baseline control circuits for preamplifiers amplifying the output signals from the photodetectors. In an alternative embodiment arrays of photodetectors are arranged to detect light scattered in different directions from the sample stream. Optics are provided to focus light scattered from different positions in the sample stream upon different photodetectors in each array so that simultaneous particles in the sample stream can be detected.

Abstract: A distance between a mask and a wafer is set such that exposure light beams emerged from the mask are converged by the projection lens to be focused on the wafer. Two light beams with same wavelength of the alignment light beam emerge from a first point (b) which is located far away from the mask, and are focused on the wafer or neighborhood of it by the projection lens. Two mask marks of diffraction gratings are formed on the mask and spaced at a predetermined distance from each other. When the alignment light beams are applied to the mask marks, two diffracted light beams of predetermined order emerge individually from the mask marks in such a manner that the respective optical axes of the two diffracted light beams, which are directed oppositely to of the diffracted light beams, intersect each other on the first point. Thus, the diffracted light beams advance as if the diffracted light beams were the two light beams emerging from the first point.

Abstract: A positional measuring laser interferometer splits a laser beam into a measuring beam and a correcting beam. Each of these beams is further split into a measurement beam and a reference beam. The reference beams travel along a fixed length path of fixed optical properties. Each of the measurement beams travels along respective optical paths in air adjacent each other so that they travel in air having substantially the same changing optical properties, such as the fraction index, preferably with the paths differing in length by a fixed amount regardless of the movement of the object to be measured. The reference beam and measurement beam, for each of the measuring and correcting beams, form an interference pattern that is detected to produce respective outputs correlated to positional information of the object and subjected to positional error due to changing refraction index of air.

Abstract: A laser light scattering and spectroscopic detector is provided which includes a probe comprising an optical fiber coupled to a graded index microlens. The angular aperture and the divergence of the probe are designed specifically to satisfy the scattering volume and coherence requirements for laser light scattering and spectroscopic measurements. The detector includes a housing which defines an elongate cell therein and a selected number of detector ports extending at various angles with respect to the cell. A method is provided for detecting scattered light which includes the steps of positioning the probe inside or outside the scattering medium at a selected angle with respect to the laser beam.

Abstract: The invention relates to a method and a system for measuring the microstructure of technical surfaces on the principle of the interference microscope. In accordance with the invention, the virtual planes of reflection present in the object beam space and reference beam space are imaged in an optically conjugated manner by different offsets, while the point at which the beam is split and the point where it is recombined are separated in space and a correction is performed such that the object beam and reference beam propagate parallel to one another in a common beam space. In this manner it is possible, in interferometric measurement, to eliminate undesired circular interference structures and render unnecessary any physical reference surface.

Abstract: The present invention relates to a photo-counting Fourier spectroscopic apparatus which enables spectroscopic detection of extremely fine emission light seen in a living-body specimen or the like as bioluminescence, chemiluminescence, and fluoroescence from a living-body specimen. A light from a specimen which emits an extremely faint light is guided to an interferometer. A two-dimensional photon counter is used as an interference fringe detector. The two-dimensional photo counting device counts the number of incident photons to form an image. The obtained image is subjected to Fourier analysis to thereby obtain spectral information about the incident light. A double beam interferometer, a triangular common path interferometer, a Michelson interferometer and other interferometers are used.

Abstract: A calibration device is provided for in vitro calibration of a light guide. The calibration device has a surface defining a cavity having an open end and a closed end opposite the open end. The opening is sized to receive the end portion of a light guide and a stop is provided near the closed end to prevent the light guide from contacting the inner surface of the closed end and to define an air gap between the end face of the light guide and the inner surface of the closed end. The inner surface of the closed end is flat and perpendicular to the longitudinal axis of the light guide. The light guide directs light from the end face of the light guide across the gap and against the flat surface. The calibration device is formed of a suitable material, such as polyethylene, with a plurality of light scattering particles and a plurality of light absorbing particles having neutral density filter properties uniformly distributed therein.

Abstract: An averaged diffraction moire position detector has a pair of diffraction gratings. One of the gratings has two grating portions arranged with an offset of half a pitch of the transit portions and the non-transit portions for light. The intensities of light passing through respective grating portions are added to cancel any error component is displacement signals produced when two parts of, for example, a machine tool move. Another averaged diffraction moire position detector uses offset in phase of respective error components contained in the diffracted light of plus and minus of the same number-order. Thus, the intensities of respective diffracted light are added to cancel respective error components, resulting in correct displacement signals being produced.

Abstract: A system for a Mach-Zender interferometer which eliminates amplitude modulation of the input light and determines the frequency modulation. Two photodetectors in series are used to receive two outputs of two arms of a Mach-Zender interferometer. The outputs of the photodetectors are summed. The path length difference is controlled by a heater which itself is controlled by a controller. The controller selectively controls the heater based on how much non-zero components are present in the output of the photodetectors.

Abstract: An apparatus for optically measuring the roughness of a surface of a subject in a non-contacting manner, based on a heterodyne interference wherein a phase of a beat beam produced by a reference laser beam, and a measuring laser beam reflected by the surface of the subject and having a wavelength different from that of the reference laser beam is changed with a change in the length of an optical path of the measuring laser beam, which occurs due to a change in the surface roughness of the subject. The apparatus includes a laser source for producing the reference and measuring laser beams, a lens device having an object lens for converging the measuring laser beam on the subject surface, and a deflector for deflecting the measuring laser beam before the measuring laser beam is incident upon the subject surface, whereby the point of convergence of the measuring laser beam is moved on the subject surface in a direction parallel to the surface, while the subject is held stationary.

Abstract: An interferometer with a cylindrical lens which produces an interferogram imaging the field of view in the redundant coordinate onto a photon noise limited detector comprising a charge-coupled device or CCD having pixels aligned along two dimensions to provide spatial resolution in that dimension of the light source as well as spectral resolution. The CCD is also characterized by greater dynamic range, lower pixel response variation, and is photon noise limited, all of which enhances its use as a detector for a spectrometer.

Abstract: Optical fiber measuring systems using an interferometer are disclosed. The measuring range of the system are extended by the use two wavelengths of radiation during the measurement. The phases of the light at each wavelength may be compared, or the radiation of one wavelength may be used to calibrate the radiation of the other wavelength.

Abstract: An opto-electronic scale-reading apparatus comprising a read head and a scale supported for displacement relative to each other for the incremental reading of marks provided on the scale. The read head includes a light source for producing light rays incident on the scale, an index grating for diffracting readable rays into fringes in at least one order of diffracton, and an analyzer grating for converting the fringes into light modulations at a rate which is a function of the rate of displacement between the read head and the scale. The scale comprises an elongate member having marks spaced in the direction of its length and spaces defined between the marks. The marks and spaces are defined by respective first and second surfaces of surface portions of the members, the first surfaces laying at an angle to adjacent second surfaces so that incident rays are reflected by the first surfaces in a first direction to be readable by the read head in the first direction.

Abstract: A dynamic light scattering apparatus (10) comprises a laser (12) optically coupled to a light scattering sample (26) via a first monomode optical fibre (18) and a first lens (22). The lens (22) produces a beam waist (24) in the sample (26), and scattered light is collected by a receive lens (30) and a second monomode optical fibre (34). The second fibre (34) has an end face in the Fourier plane (84) of the receive lens (30, 70), and defines an aperture matched to a single Airy disc (82) of the lens (30, 70). The receive fibre (34) accordingly receives a single spatial mode of light scattered from the sample (26), this mode corresponding to a single plane wave to which many scatterers contribute. The receive fibre (34) also attenuates unwanted spatial modes because of its monomode character. A photodetector (36) detects light transmitted by the receive fibre (34).

Abstract: An SHG autocorrelator for use in measuring the duration of an ultrashort pulse of light includes in one embodiment a thin pellicle beamsplitter for splitting the pulse of light into first and second beams, a stationary optical delay disposed along the path of the first beam, a movable optical delay disposed along the path of the second beam, a thin SHG crystal, a concave mirror for bringing the first and second beams to focus into the SHG crystal, a photodetector for detecting light emitted from the SHG crystal, and a narrow bandpass filter in front of the photodetector for filtering out non second harmonic light. The device reduces time broadening and delay of ultrashort pulses in the femtosecond time domain.

Abstract: A range finder for finding a distance to an object comprising an outgoing light guiding wave path, a reference light guiding wave path, and an incoming light guiding wave path. The finder further comprises wavelength changing means for changing the wavelength of the beam of light emitted from the light source, wavelength detecting means for detecting the wavelength of the beam of light emitted from the light source, and calculating means for detecting at least two peaks of the signal coming from the light receiving element when the wavelength of the light source is changed by the wavelength changing means, finding the wavelengths of the light source, respectively, from the wavelength detecting means at the time when the signal exhibits the two peaks, and calculating the distance to the object according to an operation expression memorized beforehand with reference to such obtained two wavelengths.

Abstract: A three-dimensional object is imaged by providing a coherent beam of light with a periodic variation in frequency and dividing the beam into a probe beam and a pump beam. The probe beam is directed toward the object, such that the frequency profile of the probe beam after reflection from the object is determined by the depth profile of the object. The pump beam and the reflected probe beam are directed into a nonlinear medium, such that two-wave mixing between the beams occurs in the medium, the two-wave mixing process causing the frequency profile of the probe beam to be converted to an intensity profile. The method may be further refined by adjusting the optical path length of the pump beam in order to adjust the accuracy range of the depth profile which is imaged.

Abstract: The invention relates to a method and apparatus for determining the concentration of a substance which is bonded to particles in a flowing medium, where said substance can be present in varying concentrations, a light beam (I.sub.0) being transmitted in the medium and light (I.sub.r) directly reflected from the particles being detected for obtaining a signal which is proportional to the intensity of the reflected light, said signal being used as a measure of the concentration of the substance conditional on particle concentration and opticle properties of the particles being kept constant. Detection is carried out without light passing straight through the medium, by the particle concentration of the sample taken being selected sufficiently great so that the quantity of directly reflected light will be maximum.

Abstract: The present invention provides a carrier band which is movable stepwise in its longitudinal direction past an optical measurement device and on its side facing the measurement device carries test strips to be impregnated with a test liquid running transversely to its longitudinal direction, wherein the test strips are fixed on the carrier band at equal distances to one another at least next to the edges of the carrier band. The present invention also provides a device for fixing test strips on to a carrier band.