Laser optical measuring device and method for stabilizing fringe pattern spacing
US4948257A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 23, 1989 |
| Grant date | Aug 14, 1990 |
| Priority date | — |
| Expiry date | Jun 23, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01S17/58
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Methods and apparatus for enhancing the accuracy of laser optical measuring instruments using fringe pattern spacing are disclosed. The apparatus in one embodiment includes a laser beam source 10, a beam splitter 14, and mirrors 22 to deflect the beams 18, 20 emitted from the beam splitter 14 to a sensing volume. Alternative embodiments include prisms 42, 44, gratings 62 or other optical devices in lieu of mirrors 22. Objects passing through the sensing volume scatter light which is detected by the instrument to determine, among other things, the velocity of the object. The emitted beams 18, 20 are automatically deflected in response to wavelength changes of the laser beam 16 such that variations in the fringe spacing, due to variations in laser beam 16 wavelength, are compensated by variations in the closing angle K of the emitted, deflected beams. The fringe pattern spacing is thereby held more nearly constant enhancing the accuracy of the instrument. Methods of enhancing the accuracy of measurements taken with laser optical measuring instruments are also disclosed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.