OPTICAL SCANNING DEVICE WITH PARALLEL-CONTROLLED ACTUATORS

• Main Authors: GERARD EDUARD VAN ROSMALEN, JAN PETER BAARTMAN, JAN WILLEM AARTS
• Format: Patent
• Language: English
• Published: 31.05.2006
• Subjects: INFORMATION STORAGE; INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORDCARRIER AND TRANSDUCER; PHYSICS

THE INVENTION RELATES TO AN OPTICAL SCANNING DEVICE (17) FOR USE IN AN OPTICAL PLAYER. THE SCANNING DEVICE COMPRISES AN OPTICAL SYSTEM (37) FOR FOCUSING A LIGHT BEAM (45) INTO A SCANNING SPOT (47) ON AN INFORMATION CARRIER (9) TO BE SCANNED. THE SCANNING DEVICE COMPRISES A FIRST ACTUATOR (51) BY MEANS OF WHICH THE LENS SYSTEM CAN BE DISPLACED IN A DIRECTION PARALLEL TO AN OPTICAL AXIS (39) OF THE LENS SYSTEM FOR FOCUSING THE LIGHT BEAM ON THE INFORMATION CARRIER. THE FIRST ACTUATOR IS CONTROLLED BY MEANS OF A FIRST CONTROL UNIT (87) VIA A FIRST CONTROL SIGNAL (UC1). THE LENS SYSTEM COMPRISES A MAIN OR OBJECTIVE LENS (55) AND AN AUXILIARY OR SOLID-IMMERSION LENS (54) PROVIDING THE LENS SYSTEM WITH A LARGE NUMERICAL APERTURE, SO THAT THE SCANNING DEVICE CAN SUITABLY BY USED TO SCAN INFORMATION CARRIER WITH A HIGH INFORMATION DENSITY, SUCH AS HIGH-DENSITY COMPACT DISCS. THE MAIN LENS IS ELASTICALLY SUSPENDED WITH RESPECT TO THE AUXILIARY LENS, AND THE LENS SYSTEM COMPRISES A SECOND ACTUATOR (63) FOR DISPLACING THE MAIN LENS WITH RESPECT WITH TO THE AUXILIARY LENS IN A DIRECTION PARALLEL TO THE OPTICAL AXIS TO COMPENSATE FOR A SPHERICAL ABERRATION OF THE LIGHT BEAM IN A TRANSPARENT PROTECTION LAYER (13) OF THE INFORMATION CARRIER. THE SECOND ACTUATOR IS CONTROLLED BY A SECOND CONTROL UNIT (89) VIA A SECOND CONTROL SIGNAL (uc2) ACCORDING TO THE INVENTION THE SECOND ACTUATOR IS ALSO CONTROLLED BY THE FIRST CONTROL UNIT VIA A THIRD CONTOL SIGNAL (uc3) WHICH IS PROPORTIONAL TO THE FIRST CONTROL SIGNAL. IN THIS MANNER, RESONANCES OF THE MAIN ACCURRING AS A RESULT OF ITS ELASTIC SUSPENSION ARE PREVENTED.(FIG. 2)