Appeal No. 2000-1244
Application 08/826,111
increased storage capacity is usually achieved by increasing the
storage density per unit area of the disc. See page 1 of
Appellants’ specification. An alternate method for increasing
the capacity of an optical disc is to employ additional storage
layers on a disc which can be independently recorded or
reproduced. Accordingly, the Appellants’ invention is directed
to an optical storage medium having a partially reflective layer
and a highly reflective layer, whereby data/servo
information/format information may be stored on two different
layers of the medium. See page 2 of Appellants specification.
An optical data storage system 10 according to Appellants’
invention is shown in figure 1. Optical storage medium 12
comprises a transparent substrate 14, a partially reflective thin
film layer 16 on a data pit pattern 15, a transparent spacer
layer 18, and a highly reflective thin film layer 20 on or
adjacent to a second pit pattern 19. See page 4 of Appellants’
specification.
Appellants have discovered that an excellent material for
partially reflective layer 16 is amorphous selenium. As shown in
figure 2, the refractive index of amorphous selenium has a high
real component (n) over a range of wavelengths (8) from 400 to
900 nm. A high real component n is required so that partially
2
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