Tokyo Shibaura Electric Co., Ltd.

Tokyo Shibaura Denki Kabushiki Kaisha

Tokyo Kogaku Kikai Kabushiki Kaisha

Tokyo Kagaku Kikai K.k.

Masana Minami

Hidekazu Sekizawa

Kazuaki Kimura

Tsuneo Sasaki

Teruo Murakami

Kiyoshi Yamada

Hiroshi Tamaki

Tomohide Watanabe

Masayuki Kondo

An encoder for measuring devices having a code plate including binary grating patterns arranged in a given regular fashion and forming a first scale, a linear sensor including photodiode elements arranged with fixed intervals and forming a second scale disposed in parallel with the code plate, and processor means for absolute-interpolating one pitch of the first or second scale on the basis of reading data or information obtained from the linear sensor corresponding to a relative position of the patterns to the elements. When the number of the scale divisions of the first scale within a fixed range is N, the number of the scale divisions of the second scale is N+1. Accordingly, when the first scale is a main scale, the second scale is a vernier scale. The processor means detects a phase inverting point corresponding to the interpolation point on the basis of the reading data. The processor means performs the absolute interpolation by detecting the phase inverting point.

Encoder for length or angle measuring device with high accuracy

An encoder having an optical measuring part establishing a vernier relationship between a code plate and a line sensor, and counters for obtaining a course reading from time serial output signals of the line sensor and a fine reading from the vernier relationship. Correction data including a change component in a magnification of a lens system are obtained from a counter. The correction data and the fine reading are supplied to a converting circuit to provide a corrected fine reading.

Encoder

In an optical apparatus for inspecting optical defects, a laser beam generated from a laser unit is converted by a collimator lens into a light beam having a suitable diameter. An X-Y scanner for two-dimensionally scanning the light beam is situated at a forward focal point of a scanning lens. The light beam passed through the scanning lens is converged substantially in parallel with an optical axis of the scanning lens and is reflected by a semi-transparent mirror and is vertically projected onto a flat surface to be inspected of an article situated substantially at a backward focal point of the scanning lens. Thus, on the surface to be inspected of the article there is given a projected beam spot having a larger diameter than that of the relevant circle of least confusion. The light rays reflected by the article surface to be inspected are converged by a converging lens the forward focal point of which is located on the said article surface. The light rays regularly reflected by that article surface are converged by the converging lens to a spatial filter and one cut off by the same. Only light rays irregularly reflected by the article surface enters a photo-detecting unit through the spatial filter.

Optical apparatus for measuring the size and location of optical in an

An apparatus for detecting the defects composed of non-linear components of a subject pattern, includes a laser source for illuminating the subject pattern by a laser beam, a Fourier-transform lens for projecting an information light from the pattern through a spatial filter onto a screen. The filter is placed on the Fourier-transform plane of the Fourier-transformed information light for intercepting the coherent light having information on linear components, the filter having arm sections extending correspondingly to the linear components of said normal pattern, the outer periphery of said arm sections including curved sections of a circular or elliptical shape protruding toward the intersecting point of the arms.

Apparatus for detecting the defects of a pattern with directional

An automatic focusing apparatus includes a lens for leading a laser beam onto a sample surface at a predetermined incident angle, a beam splitter to divide the reflected beam from the sample surface in accordance with the vertical shift thereof, a pair of photo diodes to respectively receive the divided beams and produce electric signals, a differential amplifier to produce a differential signal between the electric signals and a mechanism to vertically shift the stage by means of the differential signal to automatically focus a lens system on said sample surface.

Automatic focusing apparatus

An apparatus for detecting the defects composed of non-linear components of a subject pattern, includes a laser source for illuminating the subject pattern by a laser beam, a Fourier-transform lens for projecting an information light from the pattern through a spatial filter onto a screen. The filter is placed on the Fourier-transform plane of the Fourier-transformed information light for intercepting the coherent light having information of the linear components, the filter having arm sections extending correspondingly to the linear components of said normal pattern, the outer periphery of said arm sections including curved sections protruding toward the intersecting point of the arms.

Optimized spatial filter for defect detection

An optical system for a object illuminating light source includes a phase plate for giving '0'-relative phases or '.pi.'-relative phases to the incident light fluxes to cancel with respect to one another all the interference fringes except for those two light fluxes incident to define a maximum angle.

Optical system for a coherent light illuminating source

Two kinds of light sources, one of which emits a coherent light and the other of which emits incoherent light, are provided. The coherent light and incoherent light respectively emitted from the two different kinds of light sources, proceed on the same optical axis. A photomask, such as for an integrated-circuit, or other objects, which have linear straight line features and nonlinear defects, are simultaneously illuminated by the coherent light and incoherent light. The two kinds of light which pass through the photomask or other objects are transformed into a Fourier-transform pattern by a transform lens. A spatial filter, having a plurality of arms which extend in predetermined directions from the center thereof, is provided on the focal plane of the transform lens. The spatial filter suppresses the passing of coherent light having information of the linear straight line features. The coherent light which has information of the defects of the photomask is not suppressed by the spatial filter. The coherent light and incoherent light passing through the spatial filter are directed to an image plane. As a result thereof, an image of the photomask or other object, obtained by the incoherent light and an image of the defects of the photomask or other objects obtained by the coherent light, are simultaneously projected on each other on the image plane.

Apparatus for detecting the defects of the mask pattern using spatial

An optical readout device including a gas discharge display panel with spot light sources each selectively energizable to illuminate the corresponding character pattern, a memory plate which stores the character patterns, and also including an image pickup device which detects the light distribution of the character pattern illuminated with the spot light of the said gas discharge display panel.

Growing community of inventors

Kawasaki, Japan

Masana Minami