Abstract: A position detecting element that enables a position to be detected at high speed and high precision, and a range sensor using the same. The position detecting element is provided with a PIN photodiode array 1 having n segments and a parallel arithmetic processing portion 2 that calculates the segment having maximum intensity by comparing n outputs from the segments of the PIN photodiode array 1. The range sensor includes a light source by which the object to be measured is irradiated by optical beam, a lens that gathers rays of the reflected light from the surface of the object to be measured and the position detecting element mentioned above that detects the position of the light gathered by the lens.

Abstract: A back light illuminator for liquid crystal display apparatus comprises a fluorescent lamp, a light guide member, and a reflection plate enclosing the fluorescent lamp and an incident portion of the light guide member so as to reflect light rays toward the incident portion of the light guide member. The reflection plate has at least a curved portion having a parabolic cross-section or a elliptical cross-section so as not to reflect the light rays in a direction to the fluorescent lamp. Thus, absorption of reflected light by the fluorophor of the fluorescent lamp is minimized, and the luminance of the back light illuminator is increased.

Abstract: An efficient, luminous and energy-saving panel-form illuminating system suitable for mass-production, comprising at least a photoconductor, a linear light source at one side of the photoconductor, and a reflector; wherein grooves or protrusions are formed on the bottom surface of the photoconductor.

Abstract: The present invention provides an optical encoder capable of using the recesses and convexes of a movable plate and a fixed plate to accurately generate a Z phase signal in synchronism with an A/B phase signal. Phase type diffraction gratings on the moving and fixed plates including a plurality of tracks with different grating pitches cause parallel coherent beams to interfere with one another, and a light receiving part detects the intensity of light to obtain a plurality of synchronous signals with different periods. On the other hand, the light receiving part detects light spots formed by condensing elements on the movable plate to generates a single pulse per rotation as a reference position. One of the plurality of synchronous signals that has the shortest period is selected as an A/B phase signal that depends on the movement of the movable plate.

Abstract: An array light source 1 with semiconductor laser sources disposed one-dimensionally and a projective lens 2 are used to illuminate an inspected object so that light beams projected from the array light source form a dotted line on the object. A line sensor is used to receive through an objective lens 3 light emitted from an imaging area 11 away from an illuminated area 12. An image signal, fed to an image processing unit 8 through a pre-processing unit 7 producing an image from signals from the line sensor 4 and a stage 5 is processed, while the stage 5 bearing the object 6 is being gradually moved, to inspect the object 6 for crack defects 9 and 10 by detecting an optically nonhomogeneous portion of the object. The method allows a crack defect of an object, such as a ceramic substrate or a sintered metal product, to be detected fast with high accuracy.

Abstract: A phase grating has a concave part of rectangular shape type substantially, of which grating depth is deeper in a specific range than depth d' calculated in a formula.vertline.n-n.sub.0 .vertline..times.(p-d'/e)/p.times.d'=(.lambda./2).times.(1+2m) (where m=0, .+-.1, .+-.2, . . . )in terms of center wavelength .lambda. of light having partial interference to be diffracted by the phase grating, pitch length p of the phase grating, refractive index n of base material of the phase grating, refractive index n.sub.0 of medium surrounding the phase grating, and shape ratio e as the ratio of grating depth to width of slope of the concave part.

Abstract: An optical encoder has a light source and a diffracted light interference device including at least first and second diffraction gratings confronting each other, producing diffracted light beams in specific orders by passing light emitted from the light source through the first and second diffraction gratings, and making the diffracted light beams in the specific orders, which have passed through the diffraction gratings, interfere with each other to produce on-axis interference light beams in which the sum of the orders of the diffraction at the diffraction gratings is zero and off-axis interference light beams in which the sum of the orders of the diffraction is not zero. A phase device is adjusting the phases of the on-axis interference light beams and the off-axis interference light beams emitted from plural portions of the diffracted light interference device. A plurality of light sensors receive and detect the on-axis interference light beams and the off-axis interference light beams device.