Spurious signal removal in optical processor fingerprint identification apparatus
US3968476A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 17, 1974 |
| Grant date | Jul 6, 1976 |
| Priority date | — |
| Expiry date | Jul 17, 1994 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG07C9/37
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
An improved incoherent optical processor fingerprint identification apparatus employs a rotatable grating for inspecting the ridge orientations in a plurality of preselected finite sample areas of a fingerprint. A detector array including a plurality of detectors each related to a discrete sampled area is disposed to receive an image of the fingerprint filtered by the rotating grating. An incoherent light source and a lens and retroreflective prism assembly function in cooperation with the grating to produce an image thereof superposed on the grating itself such that minimum light is propagated to the detector array in the absence of an input fingerprint pattern whereas, in the presence of a fingerprint pattern, light is diffracted thereby to be filtered by the grating for supply to the detectors. Maximum light may occur at each detector under a condition of spatial alignment of the grating lines with the ridge lines of the related sampled area whereby the time interval between a reference orientation of the grating and the instant of maximum light at each detector may be converted to equivalent electrical signals uniquely representative of a particular fingerprint pattern. The sig…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.