Confocal optical imaging system with improved signal-to-noise ratio
US4634880A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 19, 1986 |
| Grant date | Jan 6, 1987 |
| Priority date | — |
| Expiry date | Feb 19, 2006 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B21/0068
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A confocal optical imaging system includes a laser for producing a linearly polarized beam which is transmitted through the optical elements of the system, focused on a small spot on the target, and reflected back through the optical elements to a photodetector where the reflectance from the spot is determined. The optical elements include a pinhole plate for restricting the size of the transmitted and reflected beams which plate, along with other of the optical elements, can produce unwanted reflections adding optical noise to the reflected beam from the target. A retardation plate between the pinhole plate and the target alters the polarization of the transmitted beam relative to the reflected beam so that a polarizer will discriminate between the true reflected beam signal and the unwanted reflections to thereby improve the signal-to-noise ratio at the photodetector.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.