Special design optical head assembly - uses internal reflection properties of prism to ensure accurate deflection of light beam

摘要

The light source and photo-detector unit (3) produces a beam of light parallel to the radial reference line (2) of an optical disc (1) under test. On entering the movable carriage assembly (4) the light beam is deflected vertically upwards by the internal deflecting surfaces (402) of a prism (4A) and passes through a condensing lens (4b) before striking the optical disc (1). The optical disc (1) reflects the light beam back along the identical path. Any light beam deviation caused by optical disc (1) surface tracking errors are registered by the photo-detector. USE/ADVANTAGE - Optical head prism action ensures that light beam is deflected vertically regardless of any misalignment introduced by optical movable carriage assembly.