Abstract

A dynamic testbed for the evaluation of optical disks has been designed and constructed. The system is achromatic within the wavelength range 440–690 nm, allowing any light source in this range to be utilized for read–write–erase experiments. In addition, the system accepts disks with substrate thicknesses ranging from 0 to 1.7 mm. The polarization handling capabilities of the testbed are such that, with the turn of a knob, one can generate either linearly polarized or circularly polarized light at the disk surface. This feature permits the testing of both magneto-optical and phase-change disks, in addition to compact disks and digital versatile disks, without any modifications to the system. A leaky polarizing beam splitter (LPBS) has been specially designed and built for this tester. The LPBS allows continuous adjustment of the ratio between p - and s-polarized components of the reflected beam that reach the detectors. This feature is especially useful for magneto-optical disks, where one can achieve an optimum signal-to-noise ratio by adjusting the relative amounts of the two components of polarization at the detection module. Focus-error detection is based on the astigmatic method, and the primary track-error detection scheme is the push-pull method, although other focusing and tracking schemes may also be implemented. The rf data signal and the focusing and tracking servo signals are all derived from the same detectors, thus allowing the optical power returning from the disk to be used in its entirety for these multiple purposes. The detection channel consists of two high-speed quad detectors mounted on the two arms of a differential detection module. By combining the various outputs of these detectors it is possible to generate the astigmatic focus-error signal, the push-pull track-error signal, the differential magneto-optical readout signal, the conventional sum signal for phase-change disk readout, and the differential edge-signal for mark-edge detection on various types of optical media.

© 1997 Optical Society of America

Versatile objective lens with adjustable correction for different wavelengths and substrate thicknesses for testing optical disks

Ronald E. Gerber, M. Mansuripur, and José M. Sasián
Appl. Opt. 36(11) 2414-2420 (1997)

Leaky polarizing beam splitter with adjustable leak ratio for operation in the wavelength range of 440–690 nm

Lu Cheng, Chanda L. Bartlett, J. Kevin Erwin, and M. Mansuripur
Appl. Opt. 36(19) 4393-4399 (1997)

Computer simulations of effects of disk tilt and lens tilt on push-pull tracking error signal in an optical disk drive

Chanda L. Bartlett, David Kay, and M. Mansuripur
Appl. Opt. 36(32) 8467-8473 (1997)

Influence of substrate thickness on optical disk readout

Joseph Braat
Appl. Opt. 36(30) 8056-8062 (1997)

Characterization of a novel focusing/tracking technique with increased feedthrough immunity for optical-disk applications: the double-astigmatic method

Bruce E. Bernacki, Keith Bates, M. Mansuripur, Delbert Hansen, and Daniel Cisneros
Appl. Opt. 32(29) 5789-5796 (1993)