Title:
REFLECTION TYPE BEAM SHAPING PRISM AND OPTICAL PICKUP DEVICE
Document Type and Number:
Japanese Patent JPH0566341
Kind Code:
A
Abstract:
PURPOSE:To reduce the size of the optical pickup device by forming a reflecting layer on one surface of a transparent triangular prism and thereby setting the angle of an incident beam and a projection beam to 90 deg.. CONSTITUTION:The reflection type beam shaping prism 18 is a triangular prism made of a transparent material and has the reflecting film 19 formed on its base and a nonreflective coat on its slanting surface 18b. The incident beam 20 is made incident from the slanting surface 18b and reflected on the reflecting layer 19 on the base 18a and the projection beam 21 is projected from the slanting surface 18b. In this case, the elliptic incident beam 20 which has a minor diameter (a) and a major diameter (b) is projected as the circular projection beam 21 which has a diameter (a) and while the beam is shaped, the projection beam 21 is polarized at right angles to the incident beam 20. Then when this reflection type beam shaping prism 18 is arranged on a projection optical path in the optical pickup device, a projection optical system and a signal optical system can be arranged nearby in the same direction, so a spacer can be omitted.
Inventors:
MAEDA HIDEO
Application Number:
JP3968091A
Publication Date:
March 19, 1993
Filing Date:
March 06, 1991
Export Citation:
Assignee:
RICOH KK
International Classes:
G02B7/18; G02B7/182; G02B27/00; G11B7/135; (IPC1-7): G02B7/182; G02B27/00; G11B7/135
Attorney, Agent or Firm:
Akira Kashiwagi
Next Patent: JPS566342