Abstract: An improved optical information recording and reproducing apparatus which is capable of detecting recording errors simultaneously with recording function for reduction of recording time, without requiring particular high accuracy for an optical system, and avoiding complication in the construction and consequent large size of the optical system.

Abstract: An image input device of a portable type includes a light source for reading an original document, a photo-electric converting element for converting reflected light from the original document into an electrical signal, a memory function section having a solid state memory element for storing the output of the photo-electric converting element, an output port for allowing external connections, and operating keys for operating the image input device. Furthermore, the image input device may include a diffraction grating for diffracting the reflected light to form an image on the photo-electric converting element and interchangeable lenses having different focal lengths for achieving various magnifications.

Abstract: An optical pickup device includes a light source, an optical lens system that converges light beams from the light source onto a recording medium, a photodetector with three divided regions that detects light beams reflected from the recording medium, and a hologram optical element that introduces the reflected light beams from the recording medium into the photodetector. The hologram optical element is divided into two regions, a part of the reflected light beams from the recording medium is diffracted by the first region of the hologram optical element and focused on a division line in the direction of the diffraction of the hologram optical element. The division line divides the photodetector into two regions, the first region and the second region. The other part of the reflected light beams is diffracted by the second region of the hologram optical element and focused on the third region of the photodetector.

Abstract: A pick-up device which includes a light source and a condenser lens for effecting recording and reproduction of information by projecting a light beam as collected by the condenser lens onto a recording medium. A diffraction grating is provided between the light source and the condenser lens for dividing light returning from the recording medium by a diffraction grating so as to be directed to a photo-detector, to thereby obtain an optical detection signal.

Abstract: A focusing error detector comprises a light source, a collimator lens for making parallel the pencil of rays emitted by the light source, an objective lens which focuses the parallel pencil of rays to form a beam spot on a data-recording disc with data tracks and guide tracks formed thereon and which receives the pencil of rays reflected from the data-recording disc, an optical system for forming a beam spot from the reflected pencil of rays incident to the objective lens, and an optical detector having a plurality of divided optical sensor blocks for receiving the formed beam spot so as to detect the focusing error of the beam spot formed on the data-recording disc on the basis of the configuration of the received beam spot.