Compact Single Element Bidirectional Optical Disk Lens Element
Original Publication Date: 1988-Aug-01
Included in the Prior Art Database: 2005-Feb-15
The fundamental component for a compact single element bidirectional optical disk lens element is a holographic element that combines the functions of a mirror, a lens, and possibly a beam circularizer as shown in Fig. 1. Due to their small size and low mass, it is possible to mount two independent holographic head elements on one actuator, one for reading the top disk and one for the bottom disk. This opens up many multiplexing opportunities which will be discussed later. At this point we concentrate on an embodiment which is seen as optimal in size, mass, and motion requirements. The holographic elements described above can be recorded as either transmission or reflection holograms as shown in Figs. 1a and 1b. A transmission hologram can be recorded to read out the top disk.