Method of measuring velocity gradients in a flowing medium and apparatus for carrying out the method
US4572664A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Mar 28, 1983 |
| Grant date | Feb 25, 1986 |
| Priority date | — |
| Expiry date | Mar 28, 2003 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01P5/26
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
In a method of measuring velocity gradients in a sample volume (2) in a flowing medium, by which method radiation scattered by particles entrained by the medium and irradiated by spatially coherent electromagnetic radiation, in particular laser light, is detected and measured and the difference in Doppler shift in the radiation from different particles in the sample volume (2) used as a measure of the velocity gradient, an optical element (3) is inserted in the radiation path from particles in the sample volume (2) to the detector (4). The optical element (3) has such properties that essentially only radiation scattered simultaneously from particle pairs in the sample volume (2) spaced apart a distance determined by the optical element (3) are made part of the measuring signals to be combined to form the signal which is a measure of the difference in the Doppler shifts and thereby of the velocity gradient in the sample volume (2) defined by the measurement points. The optical element (3) may for example be an optical grating of the absorption, phase or reflection type or intermediate forms, a birefringent element, a Bragg cell, a combination of a totally reflective surface and a be…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.