[OPTICAL REVIEW Vol. 1, No. 1 (1994) 33-35]

Single Telephoto Lens for Focus Error Detection with Astigmatic Method

Yasuhiro TANAKA,1 Hideki AIKOH,1 Isamu YANO,2 Takahisa KONDOU1 and Masaaki SUNOHARA1

1Materials and Devices Laboratory and 2Product Development Engineering Center, Matsushita Electric Industrial Co., Ltd., 1006, Kadoma, Kadoma, Osaka, 571 Japan

(Accepted July 22, 1994)

An astigmatic method for focus error detection has been integrated into a singlet. The first convex and the second concave surfaces compose a telephoto system with a telephoto ratio of about 0.4. The first surface of the lens is rotationally symmetrical asphere and the second surface is a toric shape whose aspherical profiles correct spherical aberration. We implemented our optical design using a molded glass process. Its performance was confirmed using the optical head of a magneto-optical disk system.

Key words : optical head, molded glass, asphere, toric, focus error, lens design, spot diagram