| 摘要 |
PURPOSE:To miniaturize an optical disk memory device and to shorten the access time by using a hologram in the principal part of an optical pickup to miniaturize the optical pick-up and reduce the weight. CONSTITUTION:A light source 11 which emits a coherent light, a collimating hologram lens 31A, a quarter-wave plate 15, an objective hologram lens 32, a condensing hologram lens 31B, and a photodetector 18 which detects a signal light are provided, and the light is transmitted through a Wollaston prism 33 to spatially separate the collimated light going from the light source 11 to the objective hologram lens 32 and the signal light going from the objective hologram lens 32 to the photodetector 18 from each other. The hologram is a very thin film, and optical lenses are substituted with hologram lenses to miniaturize the optical pickup considerably and reduce the weight, and the cost of parts is reduced and the assembling time is shortened to reduce the cost. |
