Abstract

There are several types of micro lenses commonly used in optical data storage systems. The most common are molded glass and molded plastic lenses. Molded optics weigh less than conventional multiple-element designs. Typical apertures are 3.5mm to 4.5mm in diameter, and numerical apertures (NAs) range from 0.45 to 0.55. For optical data storage applications, the smallest molded micro lenses available have an entrance pupil diameter (d) of 3.0mm. (1) There are several reasons to use smaller optics. If a smaller micro lens is used as an objective lens, the same number of disks can fit into a smaller stack height, and volumetric storage density will increase. If all hardware dimensions scale linearly with optics size, a reduction in lens size by some factor will allow a reduction in moving mass by that factor to the third power, since mass scales with volume. The result will be an improvement in access time.

© 1991 Optical Society of America