Improving efficiency of beam splitter for DVD pickup

Wen Jie Chen*, Cheng-Huan Chen, Han Ping David Shieh

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review

Abstract

The majority of the beam splitters for three beam tracking in commercial DVD pickup employ lamellar phase gratings, which already provides sufficient efficiency. However, for a pickup with all diffractive elements, the power budget becomes more critical, and a higher efficiency of the beam splitter is required. In this paper, we have investigated and will present the influence of the desired energy ratio between the zeroth order central beam to the first order side beam on the total efficiency of the beam splitter. The simulation based on scalar diffraction theory shows that the total efficiency of a lamellar phase grating will drop as the ratio decrease, which can be improved by employing a more sophisticated surface relief. The equal-side triangular profile has been investigated as a solution and the geometrical size of the profile has been optimized for several desired energy ratio. For a low cost fabrication process with photolithography, the total efficiency loss due to quantization with different quantization levels of the triangular surface relief has been estimated with scalar diffraction theory. This paper is concluded with a table of optimal phase level for a given energy ratio and desired minimum total efficiency with the consideration of fabrication cost.

Original languageEnglish
Article number13
Pages (from-to)121-128
Number of pages8
JournalProceedings of SPIE - The International Society for Optical Engineering
Volume5523
DOIs
StatePublished - 1 Dec 2004
EventCurrent Developments in Lens Design and Optical Engineering V - Denver, CO, United States
Duration: 4 Aug 20045 Aug 2004

Keywords

  • Beam splitter
  • DVD pickup
  • Diffractive optical element

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