INCLINATION DETECTOR, OPTICAL HEAD, OPTICAL INFORMATION PROCESSOR COMPUTER, VIDEO RECORDER, VIDEO REPRODUCER, AND CAR NAVIGATION SYSTEM

摘要

Light from a light source (1) is split by an optical splitting means (2) into a main beam and at least two subbeams. A focusing optical system (6) focuses the main beam and the subbeams to the vicinity of an optical disc (7) such that their focal points are different in the direction of the optical axis of the focusing optical system (6) and the direction orthogonal thereto. A detecting means (9) detects relative inclination of the optical disc (7) to the optical axis of the focusing optical system (6) by detecting the spot size on the detecting means (9) of the subbeam reflected off the optical disc (7). Relative inclination of the optical disc (7) to the optical axis of an optical head can thereby be detected with high accuracy without increasing the size or the cost of the optical head.