Optical disk drive relative position sensor

• Main Authors: AVILES; HENRY E, CHILDERS; EDWIN R, STAHL; RONALD P, OVERACKER; JAMES L
• Format: Patent
• Language: English
• Published: 10.08.1993
• Subjects: INFORMATION STORAGE; INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORDCARRIER AND TRANSDUCER; PHYSICS

An optical disk drive is disclosed in which sensing the position of a tilting prism driven by a fine tracking actuator uses the optical beam prior to its interaction with an optical disk. The optical beam emitted by a laser is redirected by the tilting prism. Most of the optical beam is reflected by the tilting prism in a direction through an objective lens for focused interaction with an optical disk. assuming a disk is mounted in the optical disk drive. The remainder of the optical beam is transmitted through the tilting prism, including any offset of the beam resulting from the refraction characteristics of the tilting prism, and received by a split far field detector. The split far field detector measures the offset of the optical beam which is a direct measure of the rotational position of the tilting prism. A relative position error signal is then generated and input to the coarse tracking actuator to coordinate its operation with that of the fine tracking actuator.