optical head device

Abstract

Abstract PURPOSE:To obtain the optical head of high reliability and to obtain the hologram element of high accuracy and high refracting efficiency by using two wave surfaces, which are generated from a refracting element, for optical beam control and differentially detecting the pattern on a condenser spot with an optical detector. CONSTITUTION:A beam from a light source 1 is made parallel by a lens 2 and condensed on a disk 4 through a lens 3. At such a time, a hologram element 6, which records the wave surface to include astigmatism, exists between the lens 2 and 3 and 0-th order transmitting light is condensed by the disk 4 in an outgoing path. A reflected beam is made parallel again by the lens 3 in an incoming path and incoming to the element 6. Then, in addition to the 0-th order transmitting light, the astigmatism reproducing image and wave surfaces 61 and 62, which are sharing images, are generated. One of the incoming beams in the photoelectric converting surfaces of an optical detector 5 goes to be the wave surface 62 and it is arranged on a straight line X-X', which goes through a light emitting point, together width the sharing image 61. Accordingly, by executing the differential detection of the beam 62 by detectors 51 and 52, the optical head of the high reliability can be obtained.

Inventors

• 👤 Makoto Kato
• 👤 誠 加藤

Bibliographic Details