Abstract: A light beam emitted from a semiconductor-laser light source is projected onto a diffraction-grating scale after passing through a collimator lens, a beam splitter and a central portion of an annular reflection grating. Two diffracted light beams reflected from the diffraction-grating scale are projected onto the annular reflection grating. The annular reflection grating diffracts the light beams projected onto all portions thereon to a substantially original direction to be projected onto and diffracted from the same position on the diffraction-grating scale. The diffracted light beams are superposed and the resultant light beam is returned to the beam splitter. The light beam is guided by the beam splitter in a direction different from the semiconductor-laser light source, and is detected by a photosensor as an interference light beam.

Abstract: A light beam emitted from a semiconductor-laser light source is projected onto a diffraction-grating scale after passing through a collimator lens, a beam splitter and a central portion of an annular reflection grating. Two diffracted light beams reflected from the diffraction-grating scale are projected onto the annular reflection grating. The annular reflection grating diffracts the light beams projected onto all portions thereon to a substantially original direction to be projected onto and diffracted from the same position on the diffraction-grating scale. The diffracted light beams are superposed and the resultant light beam is returned to the beam splitter. The light beam is guided by the beam splitter in a direction different from the semiconductor-laser light source, and is detected by a photosensor as an interference light beam.

Abstract: A light beam emitted from a semiconductor-laser light source is projected onto a diffraction-grating scale after passing through a collimator lens, a beam splitter and a central portion of an annular reflection grating. Two diffracted light beams reflected from the diffraction-grating scale are projected onto the annular reflection grating. The annular reflection grating diffracts the light beams projected onto all portions thereon to a substantially original direction to be projected onto and diffracted from the same position on the diffraction-grating scale. The diffracted light beams are superposed and the resultant light beam is returned to the beam splitter. The light beam is guided by the beam splitter in a direction different from the semiconductor-laser light source, and is detected by a photosensor as an interference light beam.

Abstract: An apparatus having a first system for forming a composite light beam of two light beams to be made to interfere with each other, a splitting member for amplitude-splitting the composite light beam into three or more split light beams in the same area, and a second system for obtaining interference light beams of different phases from the plurality of split light beams.

Abstract: This specification discloses an apparatus comprising a first system for forming a composite light beam of two light beams to be made to interfere with each other, a splitting member for amplitude-splitting the composite light beam into three or more splitted light beams in the same area, and a second system for obtaining interference light beams of different phases from the plurality of splitted light beams.

Abstract: A light beam emitted from a semiconductor-laser light source is projected onto a diffraction-grating scale after passing through a collimator lens, a beam splitter and a central portion of an annular reflection grating. Two diffracted light beams reflected from the diffraction-grating scale are projected onto the annular reflection grating. The annular reflection grating diffracts the light beams projected onto all portions thereon to a substantially original direction to be projected onto and diffracted from the same position on the diffraction-grating scale. The diffracted light beams are superposed and the resultant light beam is returned to the beam splitter. The light beam is guided by the beam splitter in a direction different from the semiconductor-laser light source, and is detected by a photosensor as an interference light beam.

Abstract: An apparatus for detecting the displacement information of an object has a light source, a diffraction grating for diffracting a light beam from the light source so that the light beam diffracted by the diffraction grating is incident on the object, and a photodetector for detecting the light from the object caused upon the incidence of the light beam thereon by the diffraction grating. Information regarding the relative displacement to the object along a predetermined direction is detected on the basis of a light detection signal from the photodetector. The diffraction grating is formed so that the light beam applied to the object may be condensed on the object in a direction in which the relative displacement to the object cannot be detected by the signal from the photodetector.

Abstract: An apparatus for detecting position change information of an object includes a contact member for contacting the object, and a detecting unit for obtaining position change information of the object by detecting a change in force applied from the object to the contact member.

Abstract: This invention relates to an apparatus for optically measuring the relative displacement of an object with a diffraction grating, and the apparatus has a light projection system for spot-projecting a light beam onto the diffraction grating and light detection means for receiving an interference light beam obtained by multiplexing diffracted light beams of different orders from the spot projection position on the diffraction grating in a state in which the wavefronts of the diffracted light beams are matched with each other. The relative displacement of the object is measured upon light reception of the light detection means.

Abstract: An apparatus for obtaining displacement information relative to a member includes a light source for illuminating a phase type diffraction grating on the member, an amplitude grating arranged at the position where interference fringes are generated immediately after emerging of diffracted light from the phase type diffraction grating illuminated by the light source, and a light-receiving element for receiving light emerging from the amplitude grating. The light-receiving element generates a periodic signal as displacement information upon relative movement of the member.

Abstract: An apparatus records information on a hard disk with a magnetic head arm provided in a hard disk drive. The apparatus comprises an interference measuring system, containing an outgoing portion for a measuring light beam to the arm and a reference light forming portion, for obtaining relative displacement information with respect to the arm by interfering the reference light with reflected light of the measuring light from the arm or a slider belonging to the arm, the interference measuring system having a light beam deflecting member for deflecting the measuring light and thus guiding the measuring light to a lateral surface of the arm or of the slider, a control system for generating a signal for positioning the arm with respect to the hard disk on the basis of the relative displacement information obtained by the interference measuring system, and a signal system for transmitting a signal for recording information on the hard disk to the magnetic head.

Abstract: In an apparatus for detecting information on the rotation of an object using a grating interference system, the present invention provides a rotation detecting apparatus, which can be sufficiently miniaturized even when using another rotation information detecting section at the same time, and an apparatus for controlling the rotation using the same. The apparatus has a first detecting device for detecting by making the diffracted light from the diffraction grating interfere to detect rotation information of the object, a second detecting device for detecting the light from the predetermined data recording section to detect rotation information of the object, and a light beam illuminating device common to the first and second detecting means for illuminating the diffraction grating and the predetermined data recording section together.

Abstract: This invention relates to an apparatus for detecting rotational information, and includes a disk attachable to a spindle, with relative rotational information of the disk to be detected. The apparatus also includes a a rotation detection grating on the disk, a main body unit independent from the disk, an optical detection unit fixed in the main body unit, a light source, a reference grating, and a light-receiving element fixed to the optical detection unit. The rotational information of the disk relative to the optical detection unit is detected by the light-receiving element by detecting a light beam which is emitted by the light source and goes via the rotation detection grating and the reference grating. A positioning block for positioning the spindle attachable to the disk is also included.

Abstract: An optical displacement detecting apparatus is provided for detecting information on a relative displacement with respect to an object having a diffraction grating. The apparatus includes a light-emitting element for emitting a diverging light beam, a ball lens for converting the diverging light beam from the light-emitting element into a nearly collimated beam, a grating interference optical system for using the light beam from the ball lens to finally form interference light in such a form that two diffracted light beams from the diffraction grating are coupled, and a light detecting element for detecting the interference light from the grating interference optical system, wherein the relative displacement information with respect to the object is attained from a periodic signal from the light detecting element.

Abstract: An optical type sensor has a light emitting element, a light receiving element, at least one optical element acting on a light beam emitted from the light emitting element, in an optical path till the light beam enters the light receiving element, and a spacer member disposed to define a spacing between the light emitting element and/or the light receiving element and the at least one optical element, the spacer member having a structure for being mounted to other member.

Abstract: An apparatus for detecting displacement information is disclosed. The apparatus is provided with a scale arranged on the side of an object of which relative displacement information is to be detected, a periodic signal generation diffraction grating formed at a predetermined pitch, and a predetermined data recording portion formed independently of the periodic signal generation and diffraction grating for detecting displacement information, a first detection system for irradiating a light beam onto the periodic signal generation diffraction grating to generate diffracted light, the first detection system forming a periodic signal corresponding to a displacement relative to the scale by detecting interference light of the diffracted light generated by the periodic signal generation diffraction grating, and a second detection system for optically detecting the predetermined data recording portion. The predetermined data recording portion also has a diffraction grating.

Abstract: In an optical displacement sensor for measuring a moving state of a moving object by projecting a light beam onto a diffraction grating provided on a surface of a scale connected to the moving object and utilizing diffracted light beams of specific orders from among diffracted light beams diffracted by the diffraction grating, a portion of the light beams incident upon the diffraction grating is reflected at a reflecting region provided on the back of the scale a plurality of times. A photosensor detects a change in the amount of light emanating from a transparent or a light-blocking reference position, formed on a region on the surface of the scale other than the region where the diffraction grating is formed. An output signal from the photosensor is utilized as a reference signal, which provides information relating to the moving state of the moving object.

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.