摘要:
Bei einer optischen Abtastvorrichtung zur Abtastung eines magneto-optischen Aufzeichnungsträgers (6) wird nach der Dreistrahlmethode derjenige Hauptstrahl, dessen Polarisationsebene in die eine Richtung gedreht ist, vom magneto-optischen Aufzeichnungsträger auf einen ersten Photodetektor (11) reflektiert und derjenige Hauptstrahl, dessen Polarisationsebene in die andere Richtung gedreht ist, vom magneto-optischen Aufzeichnungsträger auf einen zweiten Photodetektor (12) reflektiert. Das Datensignal wird aus der Differenz der Photospannungen des ersten und zweiten Photodetektors gebildet. Um störendes Rauschen im Datensignal zu vermeiden, ist der zweite Photodetektor so genau zu justieren, daß auf ihn nur der Hauptstrahl, nicht aber die Beugungsprodukte höherer und niederer als 0. Ordnung fallen. Um das Rauschen im Datensignal S zu verringern, ohne daß hierzu der zweite Photodetektor (12) genau justiert zu werden braucht, werden auf den zweiten Photodetektor (12) vom magneto-optischen Aufzeichnungsträger (6) auch die Strahlen höherer als + 1. und niederer als - 1. Ordnung reflektiert. Zur Erzeugung des Datensignals (S) werden von der Photospannung des zweiten Photodetektors (12) mindestens die von den Strahlen + 1. und - 1. Ordnung erzeugten Photospannungen abgezogen. Deshalb kann der zweite Photodetektor relativ groß gewählt werden und braucht nicht genau justiert zu werden. Magneto-optische Geräte.
摘要:
An optical pick-up apparatus comprises a light beam generating source (2), an objective lens (5) for causing a light beam from the light beam generating source (2) to impinge upon a record medium (6) and receiving a reflected light beam from the record medium (6), a beam splitter (4) for separating the reflected light beam from the light beam impinging upon the record medium (6), an analyzer (21) constituted by first and second prisms (22, 23) each made of rock crystal and bonded together for producing at least three light beams based on the reflected light beam, and a photodetecting unit (26) for detecting the light beams emerging from the analyzer (21). The analyzer (21) is so disposed that the reflected light beam from the beam splitter (4) enters into the first prism (22) to reach the second prism (23), an optical axis of the first prism (22) resides in a plane perpendicular to an optical axis of the reflected light beam entering into the first prism (22) and is inclined in relation to a plane of polarization of the reflected light beam entering into the first prism (22), and an optical axis of the second prism (23) resides in a plane perpendicular to the optical axis of the reflected light beam entering into the first prism (22) and is inclined in relation to the optical axis of the first prism (22).
摘要:
A pickup apparatus (12) for a magneto-optical recording medium comprises an optical waveguide for receiving a light beam reflected by a magneto-optical recording medium (13), and first (39) and second (33) focusing grating couplers disposed side by side on the optical waveguide for introducing the reflected light beam into the optical waveguide by exciting the same guided mode, and converging the guided optical waves. A third focusing grating coupler (32) is disposed for introducing the reflected light beam into the optical waveguide in a different guided mode and converging the guided optical wave. First, second and third photodetectors (24, 25, 26) are secured to the optical waveguide for respectively detecting the optical waves converged by the first, second and third focusing grating couplers. Tracking error and focusing error are detected based on the outputs of the first and second photodetectors, and recorded signals are detected based on a difference between the output of the first and/or second photodetector and an output of the third photodetector.
摘要:
An optical pick-up apparatus comprises a light beam generating source (2), an objective lens (5) for causing a light beam from the light beam generating source (2) to impinge upon a record medium (6) and receiving a reflected light beam from the record medium (6), a composite prism (21) constituted by a glass prism element (22), a crystal prism element (23) and a multi-layer (21a) of dielectric material provided between the glass and crystal prism elements (22, 23) which are bonded together, and so disposed that the light beam from the beam generating source (2) and the reflected light beam from the objective lens (5) enter into the glass prism element (22) through respective different optical paths, the light beam from the beam generating source (2) is directed to the objective lens (5) after passing through the glass prism element (22) and at least two light beams obtained based on the reflected light beam from the objective lens (5) emerge from the crystal prism element(23), and a photodetecting unit (26) for detecting separately the light beams emerging from the crystal prism element (23) of the composite prism (21).
摘要:
Der Datenspeicher weist eine Speicherplatte (6) auf, auf der ein von einer Laserlichtquelle (1) durch einen Strahlteiler (4) hindurch ausgesandtes Lichtbündel mit Hilfe einer Abbildungsoptik (5) fokussiert wird. Ein von der Speicherplatte (6) reflektiertes Lichtbündel wird vom Strahlteiler (4) auf eine Detektoranordnung (11) ausgeblendet. Diese besteht aus parallelen streifenförmigen Detektorflächen (111, 112), deren Längsachsen (L) senkrecht zur Projektion (62) der Tangente einer Informationsspur (61) f der Speicherplatte (6) im Strahlengang des reflektierten Lichtbündels angeordnet sind. Ein Fokusfehlersignal (FE) wird als das Differenzsignal aus der Summe der Ausgangssignale der Randstreifen (112) einerseits und des Mittelstreifens (111) gebildet. Dieses Differenzsignal wird bei korrektem Fokusabstand (d = f) der Abbildungsoptik (5) zu Null, wenn die Breite (b) dieses Mittelstreifens derart gewählt ist, daß der Mittelstreifen nur die halbe Strahlungsleistung empfängt.
摘要:
A process for accessing disk tracks in an optical storage disk using a laser beam passed through an acousto-optic deflector which generates an undeflected beam and at least one deflected beam both of which are focussed on the surface of the disk. The deflected beam is used to read or write data and the undeflected beam is used to follow a servoing structure on the disk.
摘要:
A device for processing optical data comprising: an optical waveguide formed on a substrate, a light source for the laser beam to be admitted into the waveguide, lens means provided on the waveguide for causing the beam propagating through the waveguide to emerge obliquely upward and focusing the emergent beam two-dimensionally, means for receiving the beam reflected obliquely from above, a base provided with the laser light source, the substrate and the light receiving means, a focusing drive mechanism for adjusting the position of the base upward or downward, and a tracking drive mechanism for adjusting the position of the base laterally.
摘要:
An erasing beam B1 and a recording beam B2 emitted from a laser diode array (20) are focused on different tracks of an optical magnetic disk D, the erasing beam B1 being focused on a track located ahead of a track on which the recording beam B2 is focused. The reflected beams of the erasing beam B1 and the recording beam B2 are separated respectively into two polarized components by means of a polarized beam splitter (17) and the polarized components are received by photo sensor means (23) and (24). Based on outputs of the photo sensor means (23) and (24), an address signal, a focus error signal and a tracking error signal are obtained. At the time of reproduction, the laser diode array (20) emits a reproducing beam so that the photo sensor means provide a reproduced signal.
摘要:
An error signal detecting device is composed of means for irradiating an object with a concentrated light beam, a photosensor (41 having a photoreceptor face divided into plural portions (5a, 5b) and adapted to receive the light reflected or transmitted by the object, a device (8-17) for respectively dividing a first output and a second output ob. tained respectively from the first and second portions of the photoreceptor face of the photosensor, a first comparator (18-21) for respectively comparing the outputs divided from the first output with the second output, a second comparator (27-30) for respectively comparing the outputs divided from the second output with the first output, and a device (26, 35, 36) for deriving a positional error signal indicating the positional error of the light beam spot with respect to the surface of the object, at least in one of the direction of optical axis and a direction perpendicular to the optical axis.