Share Email Print
cover

Proceedings Paper

Polarized diffractive optical element design for a multibeam optical pickup head
Author(s): Hsi-Fu Shih; Mark O. Freeman; Jau-Jiu Ju; Tzu-Ping Yang; Yuan-Chin Lee
Format Member Price Non-Member Price
PDF $14.40 $18.00

Paper Abstract

This paper addresses the design and construction of an interesting polarization-switched diffractive optical element (DOE) that generates multiple beams incident on the disk and acts as a beamsplitter and servo-generating element for light returning from the disk. In this way, data speed is increased proportional to the number of beams on the disk, and, by combining three functions into a single optical element, allows a more compact and lightweight pickup to be realized. The polarization-switched DOE is constructed as a sandwich of two pieces of some birefringent material, with one rotated by 90 degrees relative to the other so that the ordinary and extraordinary axes are interchanged, and with a common index-match layer between them. A diffractive pattern is etched into each of the two birefringent pieces. Linearly polarized light traveling from the laser towards the disk is diffracted into multiple beams by one of the diffractive patterns while experiencing no diffraction from the other. Travelling the roundtrip from the DOE to the disk and back to the DOE, the light traverses a quarter-wave retarder two times thereby rotating its polarization direction by 90 degrees. It now experiences no diffraction from the multiple beam diffraction layer, but is diffracted by the second diffraction layer, which steers it onto the photodetectors and alters the beam to create useful focus and tracking error signals. This design is important in that it provides a way for two diffractive surfaces, each acting independently with high efficiency on orthogonal polarizations of light, to be combined into a single element. Implementation and application to a multiple-beam holographic pickup head module are presented.

Paper Details

Date Published: 6 July 2000
PDF: 6 pages
Proc. SPIE 4081, Optical Storage and Optical Information Processing, (6 July 2000); doi: 10.1117/12.390509
Show Author Affiliations
Hsi-Fu Shih, Industrial Technology Research Institute (Taiwan)
Mark O. Freeman, Industrial Technology Research Institute (Taiwan)
Jau-Jiu Ju, Industrial Technology Research Institute (Taiwan)
Tzu-Ping Yang, Industrial Technology Research Institute (Taiwan)
Yuan-Chin Lee, Industrial Technology Research Institute (Taiwan)


Published in SPIE Proceedings Vol. 4081:
Optical Storage and Optical Information Processing
Han-Ping D. Shieh; Tomas D. Milster, Editor(s)

© SPIE. Terms of Use
Back to Top