Laser diode interferometer
US5135307A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 30, 1990 |
| Grant date | Aug 4, 1992 |
| Priority date | — |
| Expiry date | May 30, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01B11/2441
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A laser system for measuring dimensional aberrations across a target surface includes a laser diode for producing a diverging beam of laser emission. A mask spaced from the diode in the beam has an aperture therein and can be moved so as to translate the aperture to selected locations laterally with respect to the beam. The mask blocks emission from impinging on the target except for emission transitting the aperture. Emission reflected from a segment to the target returns through the aperture back into the laser diode. An AC current is added to the driver current to modulate the emission. A lock-in amplifier of a photodetector signal adds feedback current to the driver current to lock in phase angle, so that the feedback current is a measure of the aberrations.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.