Method for optical recording in photo-dichroic glass surfaces

DETAILED DESCRIPTION The instant invention is founded in the above-described disclosure and encompasses three developments resulting from further laboratory work with the glasses set forth in that disclosure.
Thus, thus extended research activity has evolved processes not contemplated in that earlier disclosure which, when applied to those glasses, yield products also not envisioned in that earlier disclosure.
For example, in known materials for optical recording, erasibility and permanency of the recorded information do not co-exist.
Nevertheless, the photo-anisotropic glasses of that earlier disclosure can be treated in a manner such that the physical effect of recording in the glass surface is irreversible and the inherent erasibility of the glass surface does not destroy the permanency of a recorded image.
That is, an erased 1-bit can always be distinguished from 0-bits utilizing a different read mode.
Further, a method of optical recording has been devised which allows spot sizes as small as 0.
25 micron to be recorded in the surfaces of those glasses.
Finally, the glasses of that disclosure can be treated in such a manner as to prevent later alterations, e.
g.
, 0-bits to 1-bits and/or 1-bits to erased 1-bits, after recording and error corrections have been completed.
Those developments will be discussed and illustrated in more detail in the following textual description of the inventive subject matter and in the appended drawings.