Position detecting system

Abstract

Abstract PURPOSE:To improve the position detection precision, by receiving a reflection light through a quadrangular pyramid prism by plural photodetectors and by detecting relative positions of a recording medium and an objective lens on the basis of outputs of respective photodetectors. CONSTITUTION:The reflection light from recording medium 3 is incident to regularly quadrangular pyramid prism 11 from the top side through objective lens 2, beam splitter 1, and condenser lens 4 and is divided to four upper, lower, left and right directions and advances toward corresponding condensing points. The reflection light which passed through quadrangular pyramid prism 11 is received by photodetectors 12-15 provided in different positions in the bottom face side of quadrangular pyramid prism 11, and relative positions of the surface of ibject 3 and objective lens 2 are detected by monitoring output levels of photodetectors 12-15.

Inventors

• 👤 Hiroshi Futagami

Bibliographic Details