Abstract: A semiconductor laser apparatus comprises a semiconductor substrate, a semiconductor laser which is fixed on the semiconductor substrate and a prism having a slanted plane. The prism is placed such that its slanted plane faces a side across from the semiconductor laser. The apparatus also includes an optical detector for monitoring which is formed on the surface of the semiconductor substrate. The surface is covered by the prism. The following are formed on the slanted plane of the prism: a reflection region on which the surface is processed for reflecting a part of an emitted light beam from the semiconductor laser and a transmissive refraction region on which the surface is processed such that the remaining part of the emitted light beam is transmitted and refracted to be guided to a light receiving plane of the optical detector for monitoring.

Abstract: In accordance with the invention, an optical head assembly comprises a laser light source, an objective lens for converging light emitted from the laser light source onto an recording surface of an optical recording medium, an optical detector device for detecting the light reflected upon the recording surface, a modulating diffraction grating for splitting the light emitted from the laser light source into 0th-order beam, +1st-order beam and -1st-order beam in a track direction of the recording surface, emitting the three beams toward the center of the track of the recording surface, and causing, with respect to the +1st-order beam and -1st-order beam, astigmatisms of different focal points in a direction orthogonal to the track direction, and a light-guiding device for guiding three returning beams reflected from the recording surface to the optical detector device.

Abstract: An automatic focusing apparatus to be used for an optical system comprises an image pickup device for picking up an image of the subject supported on a support by way of the optical system and transmitting video signals for the subject, an extracting device for extracting only the video signals corresponding to the pitch of movement of focus adjustment from the signals transmitted from the image pickup device and an in-focus state detecting device for determining the in-focus position of the subject with the area for in-focus detection determined by the pitch setting device and a drive for moving either the support or the optical system for focus adjustment depending on the result of detection of the in-focus state detecting device.

Abstract: An optical pickup device includes a light source irradiating a record medium with plural light spots of light emitted therefrom, a plurality of light detecting elelments to which reflected light of the light spots are guided, respectively, to adequately synthesize and compare outputs of said light detecting elements, thereby reading information recorded in tracks of the record medium, and detecting an tracking error and a focusing error, and a hologram element which splits light emitted from the light source into plural beams is disposed in an optical path between the light source and the record medium, said hologram element is split by a split line, said split line elongating in a direction perpendicular to a track of the medium on an optical axis, and a hologram pattern having a diffraction function which is substantially directed in the track direction is disposed on at least one side of said split line, thereby differentiating diffraction conditions on both sides of said split line from each other.

Abstract: An automatic focusing apparatus comprises an image pickup device for obtaining an image of a subject by way of an optical system and transmitting a video signal of the image, a device for specifying an in-focus position detection area within the field of the optical system and a CPU for storing in-focus signals transmitted from the in-focus device and detecting the in-focus position of the subject within the area predetermined by the in-focus device on the basis of the stored in-focus signals.