[OPTICAL REVIEW Vol. 12, No. 3 (2005) 260-263]
© 2005 The Optical Society of Japan

Simple and Accurate Propagation-Angle Observation of a Collimated Laser Beam within a Short Optical Path Range by Use of a Dual-Focus Fresnel Lens

Teruo FUJITA*, Keiji NAKAMURA1 and Toshiya MATOZAKI1

Department of Electrical and Electronics Engineering, Fukui University of Technology, 3-6-1 Gakuen, Fukui 910-8505, Japan
1Advanced Technology Research and Development Center, Mitsubishi Electric Corp., 1 Zusho-Baba, Nagaokakyo, Kyoto 617-5440, Japan

(Received October 5, 2004; Accepted February 2, 2005; Revised January 31, 2005)

We propose a method for observing the propagation-angle displacement of a collimated beam with respect to the travel direction of a moving part by use of a dual-focus Fresnel lens. The fabricated binary-type dual focus Fresnel lens consisting of two portions having a different focal length from each other. 0.5 mrad angular accuracy within a travel range of 16 mm was experimentally confirmed and then it was successfully applied to split-type optical head manufacturing.

Key words: optical metrology, Fresnel lens, collimated laser beam, accurate alignment, propagation-angle observation, split-type optical head, optical disc

*E-mail address: tfujita@fukui-ut.ac.jp