US4739177A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Light scattering particle detector for wafer processing equipment
Assignee: HIGH YIELD TECHNOLOGY A CORP OF CA
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Filing: 1986-09-16
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Granted: 1988-04-19
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Expires: 2006-09-16
Abstract
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.
Inventors
- 👤 Peter Borden
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 18:16
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/47; G01N21/49; G01N21/53; G01N15/00; G01N15/02; G01N15/0205; G01N2015/0238; G01N21/51; G01N2021/516
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
191 words
Apparatus for detecting particles in a vacuum, or air or fluid environment comprising: means for providing a light beam having a defined access; lens means for shaping said light beam to provide a collimated beam having a predetermined width and height; first mirror means having a first surface for providing multiple reflections of said light beam, the angle of incidence of each of said reflections of said light beam being less than 90°; second mirror means having a second surface for providing multiple reflections of said light beam that is reflected from said first surface, the angle of incidence of each of said reflections of said second surface being less than 90°; said first and second surfaces of said first and second mirror means respectively being substantially parallel and spaced from each other so that the distance between adjacent points of reflection on each surface is substantially the dimension of the width of said light beam; photodiode means for detecting light that is scattered by particles that traverse said beam, said photodiodes being spaced at a distance from each other greater than the distance between said first and second reflecting surfaces.
Claim 2
Dependent Claim
191 words
Apparatus for detecting particles in a vacuum, or air or fluid environment comprising: means for providing a light beam having a defined access; lens means for shaping said light beam to provide a collimated beam having a predetermined width and height; first mirror means having a first surface for providing multiple reflections of said light beam, the angle of incidence of each of said reflections of said light beam being less than 90°; second mirror means having a second surface for providing multiple reflections of said light beam that is reflected from said first surface, the angle of incidence of each of said reflections of said second surface being less than 90°; said first and second surfaces of said first and second mirror means respectively being substantially parallel and spaced from each other so that the distance between adjacent points of reflection on each surface is substantially the dimension of the width of said light beam; photodiode means for detecting light that is scattered by particles that traverse said beam, said photodiodes being spaced at a distance from each other greater than the distance between said first and second reflecting surfaces.
Claim 3
Dependent Claim
21 words
A particle detector as in claim 1, wherein said first mirror means and said second mirror means comprise planar dielectric mirrors.
Claim 4
Dependent Claim
18 words
A particle detector as in claim 1, wherein said angles of incidence are less than or about 15°.
Claim 5
Dependent Claim
26 words
A particle detector as in claim 1 further comprising a beam stop for terminating said beam after said beam has been reflected a plurality of times.
Claim 6
Dependent Claim
24 words
A particle detector as in claim 4 wherein said beam stop includes means for sensing the intensity of light incident on said beam stop.
Claim 7
Dependent Claim
33 words
A particle detector as in claim 5 wherein said beam stop further includes means for emitting a signal when the intensity of light incident on said beam stop falls below a preselected value.
Claim 8
Dependent Claim
19 words
A particle detector as in claim 1 wherein said means for providing a beam of light comprises a laser.
Claim 9
Dependent Claim
41 words
A particle detector as in claim 1 wherein said first means for reflecting said beam of light and said second means for reflecting said beam of light each comprises a mirror curved to reduce the divergence of said beam of light.
Claim 10
Dependent Claim
39 words
A particle detector as in claim 1 wherein said lens means includes a lens having a focal length selected to compensate for beam divergence positioned between a source of said beam of light and said first means for reflecting.
Claim 11
Dependent Claim
34 words
A particle detector as in claim 1 further comprising at least one member extending outward from one of said mirrors to prevent dust from settling on said surface of said one of said mirrors.
Claim 12
Dependent Claim
42 words
A particle detector as in claim 1 further comprising at least one opaque member extending outward from one of said mirrors to prevent light scattered from imperfections in said surface of said one of said mirrors from being detected by said photodiode.
Claim 13
Dependent Claim
29 words
A particle detector as in claim 1 wherein said lens means comprises one or more lenses which produce a beam of light having a height less than its width.
Claim 14
Dependent Claim
15 words
A particle detector as in claim 1 further including means for chopping said light beam.
Claim 15
Dependent Claim
30 words
A particle detector as in claim 1 wherein said photodiode means for detecting scattered light comprises a collecting mirror, said collecting mirror focusing said scattered light on said photodiode means.
Claim 16
Dependent Claim
31 words
A particle detector as in claim 14 wherein said means for detecting further includes means for sensing a representative of the peak amplitude of a light signal received by said photodiode.
Claim 17
Dependent Claim
45 words
A particle detector as in claim 15 wherein said means for detecting further includes an analog-to-digital converter and a microprocessor, said analog-to-digital converter providing said microprocessor with the digital representation of said representative of said peak amplitude of said light signal received by said photodiode.
Claim 18
Dependent Claim
16 words
A particle detector as in claim 1 wherein said lens means comprises a gradient index lens.
Claim 19
Dependent Claim
23 words
A particle detector as in claim 1, including a pipe section having a narrow cavity extending substantially transversely to said beam of light.
Claim 20
Dependent Claim
25 words
A particle detector as in claim 18, including window means disposed adjacent to said pipe section and between said first surface and said second surface.
Claim 21
Dependent Claim
31 words
A particle detector as in claim 18, wherein said pipe section comprises flanged portions for coupling to external pipes so that fluids or gases can be passed through said narrow cavity.
References Cited (Backward Citations)
US3431424A
Cited
US3578867A
Cited
US3704951A
Cited
US3622796A
Cited
US3772525A
Cited
US3994603A
Cited
US4473296A
Cited
US4221485A
Cited
US4299489A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-04-19 | 1991-10-19 | 1992-04-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-04-19 | 1995-10-19 | 1996-04-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-04-19 | 1999-10-19 | 2000-04-19 | $7700.00 | Window Closed / Lapsed |