| 摘要 |
PURPOSE:To immediately check the quality of recording even when the moving direction of an optical recording medium is reversed. CONSTITUTION:A light beam for reproducing information transmitted from a light emitting diode 6 is divided into a zero order diffracted light and two first order diffracted lights and projected on an optical card 1. The beams are made to be in the light-quantity modulated state by depending upon whether or not a guide track and a pit exist on the optical card 1 and normally reflected on the optical card 1. The reflected light passes through an objective lens 5 in the reverse direction, is made a parallel light, introduced to a polarization beam splitter 4 so as to be reflected and introduced to a non-polarization beam splitter 8 so as to be reflected. The light reflected by the non-polarization beam splitter 8 is converged by a condenser lens 9 and made incident on a photodetector 10. |
