| 摘要 |
PURPOSE:To decrease the number of optical parts, and to make a titled device small in size and light in weight, and to obtain the device having high reliability by forming monolithically an optical element on the same substrate, and constituting a condensing mechanism, a signal detecting mechanism, a focus sensor, and a tracking sensor. CONSTITUTION:Outgoing light of a semiconductor laser 1 is emitted as a diffused luminous flux 43 to an optical waveguide path 42, the diffused luminous flux 43 becomes a parallel luminous flux 45 by a collimating element 44, and this parallel luminous flux 45 transmits through a beam split element 46 and becomes an irradiating luminous flux 47, is condensed by a condensing element 49 and becomes an optical spot 12. Thereafter, a reflected light which has read information of an information surface 11 becomes again the parallel luminous flux for propagating in the optical waveguide path 42 by the condensing element 49, and becomes a reflected luminous flux 48 separated from the luminous flux by the beam split element 46. The reflected luminous flux 48 is divided into two luminous fluxes 51a, 51b converged by a luminous flux separating and condensing element 50. The luminous fluxes 51a, 51b are made incident on photodetectors 19a, 19b, and just in case when the information surface 11 comes to a focal position of the condensing element 49, the photodetectors 19a, 19b are placed at a condensing position of the luminous fluxes 51a, 51b. |
