
US Patent No: 4,739,177
Number of patents in Portfolio can not be more than 2000
Light scattering particle detector for wafer processing equipment
Stats
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Apr 19, 1988
Issued date -
Sep 16, 1986
filing date -
06/907,776
serial no -
Expired
status
Importance
Abstract
A particle detector includes a laser, a beam shaping lens, and a pair of mirrors which reflect the shaped laser beam back and forth between the mirrors a selected number of times in order to create a sheet of light or light net between the mirrors. The path of the beam is terminated by a beam stop which contains a photodiode to monitor beam intensity and thereby system alignment. Light scattered by a particle falling through the sheet of light is gathered and transmitted to a photodiode. A peak detector provides a measure of the peak intensity of light scattered by such a particle to a microprocessor, which counts the number of particles falling through the light net in a selected time interval. The microprocessor also uses the peak intensity to estimate the size of the particle.
First Claim
Related Publications
International Classification(s)
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Cited Art
| Patent Info | (Count) | # Cites | Year |
|---|---|---|---|
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| 4,221,485 Optical smoke detector | 16 | 1979 | |
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| 4,299,489 Device for determining the histogram of sizes of particles | 7 | 1980 | |
| 4,473,296 System and method and apparatus for a continuous aerosol monitor (CAM) using electro-optical weighing for general aerosols | 22 | 1982 | |