초록

A computer-readable medium having material at a select position therein and containing instructions for controlling an optical reader to cause the optical reader to re-read the position having the material one or more times to elicit a measurable parameter at such position.

대표청구항 ▼

We claim: 1. An optical recording medium readable by an optical reader, said optical recording medium having optical data structures thereon, said optical recording medium comprising an light-changeable material selectively positioned with respect to at least a portion of the optical data structure

We claim: 1. An optical recording medium readable by an optical reader, said optical recording medium having optical data structures thereon, said optical recording medium comprising an light-changeable material selectively positioned with respect to at least a portion of the optical data structures, and containing instructions for controlling the optical reader to cause the optical reader to detect the position(s) of the light-changeable material on the optical data structure and for permitting access to the read of the optical data structures only if the position(s) of the light-changeable material with respect to the optical data structures is in accord with reference position(s). 2. An optical recording medium in accordance with claim 1 wherein the light-changeable material is a reversible light-changeable material. 3. An optical recording medium in accordance with claim 1 wherein said instructions further direct the optical reader to alter its focal length to detect the light-changeable material. 4. An optical recording medium in accordance with claim 1 wherein the light-changeable material is in a plane different from the optical data structure. 5. An optical recording medium in accordance with claim 1 wherein the instructions further comprising directions for the optical reader to re-read the position(s) at which said light-changeable material is detected.