| 摘要 |
PURPOSE:To miniaturize a device by remarkably reducing the number of components by reflecting specific polarized light and transmitting the polarized light intersecting orthogonally with the light by using a parallel and flat type polarizing beam splitter, taking out the differential output of reflected light and transmission light, and detecting a read signal. CONSTITUTION:A light beam transmitting a 1/2-wave plate 22 and a lens 9 is made incident on a polarizing beam splitter layer 42 formed on the incident plane of a polarizing beam splitter 45. S-polarization is reflected on the polarizing beam splitter layer 42, and made incident on a photodetector 24. And P- polarization is transmitted, and a part of it is diffracted at gratings 40 and 41 formed on the emitting plane of the polarizing beam splitter 45, and diffracted at the gratings 40 and 41 formed on the emitting plane from the grating 40, and diffracted light from the grating 40 is made incident on a photodetector 44. Assuming the output voltages of the photodetectors 43 and 44 as V(43) and V(44), a tracking error signal can be obtained by V(43)-V(44). |
