Abstract: Apparatus for measuring the absolute reflectance of a sample, which comprises an integrating sphere provided with four windows the centers of which lie in a plane including the center of the integrating sphere. A first one of the four windows has its center coinciding with a diametrical line of the integrating sphere included in the plane while a second and a third window are arranged symmetrically with respect to the diametrical line, with a sample set in the fourth window so as to face inwardly of the integrating sphere. A light source is so arranged as to introduce a beam of light into the integrating sphere and a light measuring device is so arranged as to receive the light emerging from the integrating sphere. The integrating sphere is rotatable for 180.degree.

Abstract: The disclosure is directed to an apparatus for eliminating background interference during fluorescence measurements in a multiple laser flow cytometer. A biological particle stained with fluorescent dyes is excited by a laser. A fluorescence detector detects the fluorescence. The particle scatters light and a gate signal is generated and delayed until the biological particle reaches the next laser. The delayed signal turns on this next laser, which excites a different stained component of the same biological particle.

Abstract: Surface coating films containing metallic flake pigment are characterized by (a) illuminating the film with a parallel beam of light which is inclined at a given angle to the film normal and (b) measuring the intensity of light reflected from a point on the film at a plurality of azimuthal viewing positions located in a circle which lies in a plane parallel to the film and through the center of which passes the film normal at the point. Apparatus suitable for carrying out the measurements is described. The invention enables the frequency distribution of the orientations of the metallic flake in the film to be determined.

Abstract: A method and apparatus for making decay time measurements of an optical cavity having at least two reflecting optical elements by directing a beam of light into the cavity, switching the beam of light off when the intensity in the cavity reaches a predetermined threshold level, monitoring the beam intensity decay of the optical cavity, and measuring the intensity decay time either with a storage oscilloscope or a digital counter.

Abstract: In a radiation pyrometer in a gas turbine engine, non-uniformly distributed changes in transparency of an optical element in the system, e.g. contamination of pyrometer objective lens L.sub.1 by combustion products from the turbine can be automatically detected. Lens L.sub.1 focusses radiation from target T onto an additional lens L.sub.2, which in turn focusses it onto the end E of the fibre-optic bundle F. Considered reciprocally, lens L.sub.2 images the end E of fibre-optic F into L.sub.1, so that although each optical fibre in end E receives radiation from all parts of target T, each fibre is imaged into a corresponding discrete area of L.sub.1. Fibre-optic bundle F comprises two (or more) sub-bundles F.sub.1 and F.sub.2 forming complementary sub-areas of end E and each sub-bundle is provided with its own photodetector P.sub.1, P.sub.2 and associated pre-amplifier A.sub.1,A.sub.2 adjusted so that their outputs A.sub.1 S.sub.1 and A.sub.2,S.sub.2 are matched at the non-contamination condition.

Abstract: Disclosed is an improved turbidimeter or instrument for measuring the concentration of a suspension using diffuser means for converting incident light into diffused light before passing through a suspension. The use of diffused light improves the linearity of the optical density vs. concentration characteristics over a relatively wide range.

Abstract: A target plate is provided in the operating field of view of a microscopic operating system having a plurality of target patterns thereon. These target patterns include scaled rulings, to which an operating element of the system is aligned, and reflective portions for calibrating the optical elements of the system to assure even illumination of the field of view and minimal distortion. Additional target patterns include centerline rulings which intersect at right angles for calibration of Theta alignment of an operating element, and at least one matte surface for examination of the pattern recognition capability to determine contrast and video information quality. At least one checkerboard pattern of alternating reflective and non-reflective surfaces and at least one continuously reflective surface may be provided to calibrate distortion, focus, illumination, and contrast.

Abstract: An apparatus for continuously measuring the degree of milling of rice grains wherein there is provided a grain passage unit, one wall of which is positioned angularly so that the grains in contact therewith slide down with their lengthwise axes generally parallel to this wall and another wall of which is positioned so that the grains introduced in the grain passage unit flow without a gap between this wall and the grains, and wherein there are provided integrated data take-up units, the inputs of which are connected to amplifiers and the outputs of which are coupled to a degree of milling meter through an arithmetic unit so that the integrated data obtained in a given period divided into a number of divisions is averaged to calculate the degree of milling sought.

Abstract: Apparatus and method for the analysis of a stream of molten polymer for the presence of unwanted voids, gels and particles of solids by observation of the stream, utilizing an observation probe and an illuminating probe placed at an illuminating angle to the observation probe so as to establish an image observable at an observation point remote from the stream.