Abstract: A device for detecting the position of an information recording or reproducing head relative to a recording medium; the head is relatively rotatable around a first axis with respect to the recording medium, and rotatable around a second axis parallel to the first axis. The device includes an autocollimator for measuring a relative positional relationship of the head substantially along the direction of the rotation around the second axis, a rotating table on which either the combination of the recording medium and the head or the autocollimator is mounted to activate the rotational movement substantially around the second axis, and a control unit. The control unit rotates the rotating table in response to the obtained position of the head with respect to the recording medium. According to the measurement result by the autocollimator, the control unit accomplishes a relative positional controlling in which a relative positional relationship between the autocollimator and the head is kept constant.

Abstract: A rotary detector has a diffraction grating arranged circumferentially and a center at substantially the center of rotation. The rotary detector measures rotational information of a rotating object. The rotary detector is provided with a light source, an irradiating optical system for irradiating luminous flux from the light source to a first point on the diffraction grating, and an optical system for guiding two diffracted luminous fluxes emerging from the first point at an emerging angle and diffracted to have a same order but different signs to be incident at a second point on the diffraction grating at an incident angle relative to a rotational direction of the grating, with the second point positioned substantially opposite to the first point on the diffraction grating with respect to the center of the rotation, and the incident angle is the same angle as the emerging angle.

Abstract: This invention relates to a light-emitting apparatus, a photosemiconductor apparatus and a method for producing a photosemiconductor wherein the light-emitting apparatus for emitting light on an object comprises a substrate; a light-emitting element provided on the substrate; an optical member provided on a predetermined position to the substrate; a light-receiving element provided on the substrate, the light-receiving element receiving a part of light beam emitted from the light-emitting element on the object via the optical member; and means for controlling a quantity of the beam projected from the light-emitting element on the object, based on an output signal from the light-receiving element.

Abstract: An apparatus for measuring relative movement by the use of a diffraction grating includes a light beam generating portion generating a light beam including light wave components having planes of polarization orthogonal to each other, an interference optical system for directing the light beam from the light beam generating portion to the diffraction grating, the light beam directed by the interference optical system being diffracted by the diffraction grating to thereby at least create two diffracted light beams of different orders having planes of polarization orthogonal to each other, the interference optical system being disposed so as to superpose the two diffracted lights one upon the other or upon other light and cause them to interfere with each other, and a detecting system for detecting the interfering light beams from the interference optical system. The relative movement of the diffraction grating and the interference optical system is measured by the detection by the detecting system.

Abstract: A method and an apparatus for measuring a very small displacement of an object. The first and second beat signals are produced by light beams of different frequencies diffracted by a diffraction grating. The phase difference between the first and second beat signals is detected, thereby measuring the relative displacement of the diffraction grating.

Abstract: A displacement information detection apparatus for detecting relative displacement information regarding the apparatus and an object to be detected includes an illumination system for radiating coherent light. A first diffraction grating splits the coherent light from the illumination system into first and second light beams, which are radiated onto the object. A second diffraction grating synthesizes the first and second light beams emerging from the object to generate an interference light beam. A light-receiving element detects the interference light beam and detects the relative displacement information regarding the object and the apparatus upon reception of the interference light beam. The illumination system is configured to focus the first and second light beams at a location along an optical path between the first diffraction grating and the second diffraction grating, so that the interference light beam incident on the light-receiving element is a divergent light beam.

Abstract: Disclosed is a displacement detecting device for measuring displacement or velocity of an object. The device is provided with a casing having an optical window, a light-emitting element and a light-receiving element incorporated in the casing, a transparent plate member provided in the vicinity of the window, a first optical function element provided on the transparent plate member for splitting the light generated by the light-emitting element into plural light beams emitted therefrom, and a second optical function element provided on the transparent plate member for guiding the lights to the light-receiving element, the lights being modulated when the emitted light beams are irradiated onto a relatively displacing object.

Abstract: An interferometer for measuring the displacement of a diffraction grating includes a multi-mode semiconductor laser for generating a laser beam; a device for supplying a predetermined current to the laser so that at least five vertical modes occur in an oscillation spectrum of the laser beam generated by the laser at an intensity ratio of at least 0.05; and an optical system for splitting the laser beam generated by the laser into first and second beams. The optical system also directs the first and second beams to the diffraction grating and effects interference between a first diffracted light beam generated by the diffraction of the first beam at the diffraction grating and a second diffracted light beam generated by the diffraction of the second beam at the diffraction grating to produce an interference light beam. Also provided is a photoelectric convertor for converting the interference light beam into an electrical signal.

Abstract: A rotary encoder and a scanning system using the same for detecting rotation of a galvano scanner which comprises a rotary scale coupled to a rotating driver, a scale with slits formed at a non-uniform pitch circumferentially on the rotary scale within a limited rotation angle and detection means for detecting a rotation status by reading the slits.

Abstract: A light beam is incident on a first position on a scale at such an angle that diffracted lights substantially coincide with an incident optical path, and two diffracted lights are directed along a substantially common optical path and are incident on a second position symmetrical with the first position. An interference light formed by rediffracted lights reflected from the second position is detected to thereby detect the displaced state of the scale.

Abstract: A method of and apparatus for optically detecting the position or amount of movement of a movable object, in which a plurality of position data element arrays are provided on a scale attached to the object such that the arrays are arranged in the direction of movement of the object. A string of light beam such as a laser beam, which extends in the same direction as the position data element array, is made to illuminate one of the arrays, and the light reflected by or transmitted through the position data element array is received by a sensor array such as CCD sensor which produces a signal representing the pattern of arrangement of the data elements in the illuminated position data element array and indicating absolute position of the object, whereby the instant absolute position of the object is detected.

Abstract: An encoder includes a first polarizing beam splitter for splitting a beam into first and second beams, and a first .lambda./4 plate arranged in respective first and second optical paths. A first optical device causes the beams to be incident on a diffraction grating so that positive first and negative second mode diffracted beams travel along the first and second optical paths, respectively, and superposes the diffracted beams on each other. A second polarizing beam splitter splits the diffracted beams from each other, and a second .lambda./4 plate is arranged in third and fourth optical paths for the diffracted beams, respectively. A second optical device causes the diffracted beams to be incident on the diffraction grating so that positive and negative first mode rediffracted beams travel along the third and fourth optical paths, respectively, and superposes the rediffracted beams on each other.

Abstract: A rotary encoder wherein coherent beams are caused to be incident at different positions of a diffraction grating mounted on a rotary object, different beams diffracted from the diffraction grating are caused to overlap and form interference fringes, the fringes are detected by a light receiving detector to detect a rotational state of the rotary object, and the parallelism a of the rotary object satisfies the following inequality:a.ltoreq.tan.sup.-1 [{.pi.(m-n).lambda./360n.sub.0 P}.theta.k].

Abstract: Disclosed is an optical apparatus which can be used for measuring displacement of an object. The apparatus includes an optical system for forming a linearly polarized beam whose polarization direction changes, a reflecting surface for reflecting the beam and for directing the beam in a predetermined direction, a photoelectric converter for photoelectrically converting a reflected beam directed in the predetermined direction, a polarizing device, arranged in an optical path of the reflected beam, for directing only a P-polarized beam or an S-polarized beam of the reflected beam toward the photoelectric converter.

Abstract: A displacement measuring apparatus comprises a scale relatively displaced to an irradiating beam, a reading head to read the scale by the irradiating beam, and control device to control the apparatus for avoiding substantially the leakage of the irradiating beam out of the apparatus in response to the positional error of the scale and the irradiating beam.

Abstract: A device comprises output device for receiving signals having predetermined phases and outputting first and second signals having different phase angles and amplitudes, conversion device for converting the first signal into a first binary signal and the second signal into a second binary signal, the conversion device being arranged so that widths of the first and second binary signals are substantially equal to each other regardless of a difference in amplitude of the first and second signals, and generating device for generating first and second pulses according to phase angles on the basis of the first and second binary signals.

Abstract: A reference position detecting device comprises an optical device for directing a light beam to a pattern indicating the reference position and plural photoreceptor elements for receiving the light beam obtained through the pattern. A reference position signal is obtained from signals from the photoreceptor elements.

Abstract: An encoder for measuring movement of an optical scale by photoelectrically converting light from the optical scale obtained by applying light from a light source to the optical scale, by means of light receiving element, includes detector for detecting a variation in intensity of the light received by the light receiving element and a comparator for comparing a signal from the detector with a predetermined reference signal. Consequently, a predetermined alarm signal is generated on the basis of the result of comparison obtained from the comparator.

Abstract: A scale, for measuring the displacement of an object to be examined, has a division and a mark for alignment of the division, and a displacement measuring apparatus, for measuring the displacement of a scale, has a device for reading the division of the scale and a detector for detecting the positional error of the division relative to the direction of the displacement.

Abstract: An encoder in which a light beam emitted from a semiconductor laser or the like is applied to a diffraction grating from a predetermined direction which is not contained in a reference plane defined by direction of relative movement of the diffraction grating and a direction normal to the diffraction grating. A diffracted light created from the diffraction grating by the application of the light beam by the light applying means is reflected by re-entering means and the reflected light is caused to re-enter the diffraction grating at substantially the same position as the position at which the diffracted light is created.