[OPTICAL REVIEW Vol. 19, No. 6 (2012) 419-421]
© 2012 The Japan Society of Applied Physics

Low-Dispersion Characteristics of Silica-Based Graded Refractive Index Lens for Laser Display Optical System

Taro SUZUKI1* and Sunao KURIMURA2

1TOYO GLASS Co., Ltd., 3-2-3 Yakoh, Kawasaki-ku, Kawasaki 210-0863, Japan
2National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan

(Received May 31, 2012; Revised July 14, 2012; Accepted July 24, 2012)

We report the characteristics of silica-based graded refractive index lens fabricated by sol–gel method. Lens diameter is precisely controlled to be 125 μm± 0.5 μm. Chromatic dispersion is defined as the difference of refractive index distribution coefficient, and concluded to be sufficiently low against ordinary achromatic lenses. We also calculated the difference of focal distance among RGB wavelengths, the difference was from 25 to 35 μm almost regardless of the lens length. Divergence angle dispersion was suppressed less than 10 per cent, demonstrating excellent achromaticity for raster-scanning laser display devices.

Key words: graded refractive index lens, GRIN lens, sol–gel method, chromatic dispersion, refractive index distribution coefficient, output beam divergence angle

*E-mail address: taroh_suzuki@toyo-glass.co.jp