Abstract

The purposes for achromatizing the optics in an optical recording head are: (a) to reduce focal shifts of the spot at the disk¹ and in the focus sensing system when the laser wavelength shifts and (b) to eliminate lateral shifts of the spot at the disk. Reference 1 discusses the use of a very low dispersion glass in the fabrication of molded singlet lenses for use in optical data storage. This paper discusses an effect of a lateral shift² of the focal spot that occurs due to the dispersion in the beam expansion prism when the laser mode hops.

© 1991 Optical Society of America