Beam forming apparatus for aerodynamic particle sizing system
US4917494A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 9, 1988 |
| Grant date | Apr 17, 1990 |
| Priority date | — |
| Expiry date | Sep 9, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2015/1447
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
Apparatus, intended primarily for use in an aerodynamic particle sizing system, for generating a pair of closely-spaced light beams, each having a thin, elongated cross-sectional shape. Particle sizes are determined by directing a particle stream through the light beams and measuring the times of flight of particles between the two light beams. The apparatus for generating the light beams includes a laser source and beam forming optics. In one embodiment, a first light beam is formed at the particle stream by a cylindrical lens. After passing through the particle stream, the first light beam is reflected and focused to form a second light beam at the particle stream that is displaced from the first light beam. The first light beam can be reflected and focused by a concave cylindrical mirror or, alternatively, by a flat mirror and a convex cylindrical lens. In another embodiment, the incident light beam from the laser source is passed through a diffraction grating which provides a zero order lobe and a first order lobe. The zero order lobe and the first order lobe are focused at a particle stream by a cylindrical lens to form the first and second beams.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.