PURPOSE: To prevent any adverse influence such as reducing a signal level or the like because of C/N deterioration by elliptically polarizing a laser beam even when an objective lens or the like has birefringence by setting the advanced phase axis or delayed phase axis of a birefringence optical element in a prescribed direction.
CONSTITUTION: When an angle formed between a deflecting phase 33 of the laser beam made incident an objective lens 10 or the like and an advanced phase axis 31 of the lens 10 having birefringence is set at ±90°, the polarizing phase 33 is coincident with a delayed phase axis 32, and the laser beam is elliptically polarized. Thus, the level of the signal through the lens 10 is made maximum and even when the optical equipment such as the objective lens or the like has birefringence, the adverse influence such as reducing the signal level or the like by the C/N deterioration caused by the birefringence is prevented.
KAMIYANAGI KIICHI
YASUKAWA KAORU
MURAKAMI AKEMI
| JPS62132247A | 1987-06-15 |