Focus controller

Abstract

Abstract PURPOSE:To stably control a focus even when a light beam crosses groups as tracks on an optical disk successively by providing a supporting member to support plural refracting bodies, which one part of the light beam from an information recording medium passes, around an optical axis mutually in a point symmetry. CONSTITUTION:The light beam emitted from a light source 11 is focused on an information recording medium 1 by using a focusing means, and light beam components passing through plural refracting bodies provided in the light path of the reflected light beam and arranged in the point symmetry and the light beam components made incident without passing through the refracting bodies are detected. The detected detecting signal is processed, a control signal is generated, and by the control signal, the condition of the light beam converged on the information recording medium 1 is controlled. Since plural refracting bodies are supported in the point symmetry by means of the supporting member beforehand, the adjustment and assembly of an optical system can be made easy. Thus, the focus can be stably controlled.

Inventors

• 👤 Atsushi Ishihara
• 👤 Takeshi Ishika

Bibliographic Details