Apparatus for measuring non-absorptive scattering
US5052806A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 21, 1990 |
| Grant date | Oct 1, 1991 |
| Priority date | — |
| Expiry date | May 21, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01J9/04
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Apparatus is provided for measuring non-absorptive scattering with an exceptionally high degree of accuracy. In the preferred mode, the apparatus can also be used to measure absorptive scattering, thus providing a method of distinguishing absorptive scattering from scattering due to transparent moieties (i.e. non-absorptive scattering). The approach of the invention promises to significantly expand the use of optical systems in quality control. The general concept of the invention relies on symmetric heterodyne scattering. Specifically, two beams at slightly differing optical frequencies are directed to intersect at some arbitrary angle. Transparent objects within the intersection volume scatter light from each beam into the other. After intersecting, the two beams are directed to separate photodetectors which mix each transmitted beam with the scattered light from the other beam. Because the two beams are at different optical frequencies, the mixing of the light generates heterodyne (beat) signals modulated at the difference frequency on each of the photodetectors. These signals can then be combined in various ways to directly measure the absorptive and non-absorbtive scattering f…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.