Holographic reading apparatus with an area identification and density reference scan
US4149269A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 28, 1977 |
| Grant date | Apr 10, 1979 |
| Priority date | — |
| Expiry date | Sep 28, 1997 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C13/04
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A large number of closely spaced holograms are formed on a sheet, each hologram comprising an information portion and an identification portion. First scan means movably position the sheet relative to a reconstruction beam and a sensor means for reading a selected hologram. The sensor means reads the identification portion of the reconstructed hologram to determine whether said hologram is the selected hologram. If said hologram is the selected hologram, a second scan means is actuated to read the information area. If said hologram is not the selected hologram, the first scan means is actuated to move to the next hologram. The process is continued until the selected hologram is located. The identification area further comprises a density reference section which is read to produce a bias reference signal for combination with the information signals. In digital applications the bias reference signal establishes the quantization threshold. In analog applications the bias reference signal establishes the bias point for differential amplification.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.