US4508970A
Expired / Lapsed
US
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Melt level sensing system and method
Assignee: Motorola Solutions Inc
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Filing: 1982-07-15
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Granted: 1985-04-02
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Expires: 2002-07-15
Abstract
Abstract A sensing system and method for detecting changes in the level of a liquid surface utilizing a source of essentially monochromatic illumination of narrow beam width for directing an incident beam toward a liquid surface at an oblique angle thereto, and thereby providing a reflected beam therefrom. A beam expander is interposed between the illumination source and the liquid source for increasing the narrow beam width of the incident beam to a beam width substantially greater than the wavelength of disturbances in the liquid surface. A converging lens is mounted transverse to and intercepts a portion of the reflected beam from the liquid surface for focusing that portion of the reflected beam to a centrum. A beam detector is positioned adjacent to the centrum for providing an indication of changes in the level of the liquid surface by detecting corresponding changes in a relative position of the centrum. An optical filter can be used to intercept the reflected beam to allow only the frequency of the monochromatic illumination source to pass therethrough in a Czochralski furnace.
Inventors
- 👤 Charles B. Ackerman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 10:48
CPC Classifications
G; G01; G01F; G01F23/00; G01F23/22; G01F23/28; G01F23/284; G01F23/292; G01F23/2921; G01F23/2928; Y; Y10; Y10S; Y10S117/00; Y10S117/90; Y10S117/903; Y10S117/904; Y10T; Y10T117/00; Y10T117/10; Y10T117/1004; Y10T117/1008
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
143 words
A sensing system for detecting changes in the level of a liquid surface comprising: a source of essentially monochromatic illumination of narrow beam width for directing an incident beam toward said liquid surface at an oblique angle thereto, and providing a reflected beam therefrom; a beam expander interposed between said illumination source and said liquid surface for increasing said narrow beam width of said incident beam to a beam width substantially greater than the wavelength of most disturbances in said liquid surface; a converging lens transverse to and intercepting a portion of said reflected beam from said liquid surface for focusing said portion of said reflected beam to a centrum; and a beam detector positioned adjacent to said centrum for providing an indication of changes in said level of said liquid surface by detecting corresponding changes in a relative position of said centrum.
Claim 2
Dependent Claim
143 words
A sensing system for detecting changes in the level of a liquid surface comprising: a source of essentially monochromatic illumination of narrow beam width for directing an incident beam toward said liquid surface at an oblique angle thereto, and providing a reflected beam therefrom; a beam expander interposed between said illumination source and said liquid surface for increasing said narrow beam width of said incident beam to a beam width substantially greater than the wavelength of most disturbances in said liquid surface; a converging lens transverse to and intercepting a portion of said reflected beam from said liquid surface for focusing said portion of said reflected beam to a centrum; and a beam detector positioned adjacent to said centrum for providing an indication of changes in said level of said liquid surface by detecting corresponding changes in a relative position of said centrum.
Claim 3
Dependent Claim
42 words
The system of claim 1 further comprising: a filter interposed between said converging lens and said liquid surface for intercepting said portion of said reflected beam and transmitting therethrough an optical signal of substantially said monochromatic illumination frequency to said converging lens.
Claim 4
Dependent Claim
13 words
The sensing system of claim 1 wherein said illumination source comprises a laser.
Claim 5
Dependent Claim
14 words
The sensing system of claim 3 wherein said said laser comprises a HeNe laser.
Claim 6
Dependent Claim
22 words
The sensing system of claim 1 wherein said incident beam beam width is increased by said beam expander to substantially 16 millimeters.
Claim 7
Dependent Claim
26 words
The sensing system of claim 1 wherein said beam detector comprises a pair of photodiodes providing a null output when said centrum falls directly between them.
Claim 8
Dependent Claim
158 words
A Czochralski furnace including a melt crucible containing a liquid surface of variable level comprising: a source of essentially monochromatic illumination of narrow beam width for directing an incident beam toward said liquid surface at an oblique angle thereto, and providing a reflected beam therefrom; a beam expander interposed between said illumination source and said liquid surface for increasing said narrow beam width of said incident beam to a beam width substantially greater than the wavelength of most disturbances in said liquid surface; a filter intercepting a portion of said reflected beam and transmitting therethrough an optical signal of substantially said monochromatic illumination frequency; a converging lens transverse to and intercepting said optical signal from said filter for focusing said optical signal to a centrum; and a beam detector positioned adjacent to said centrum for providing an indication of changes in said level of said liquid surface by detecting corresponding changes in a relative position of said centrum.
Claim 9
Dependent Claim
158 words
A Czochralski furnace including a melt crucible containing a liquid surface of variable level comprising: a source of essentially monochromatic illumination of narrow beam width for directing an incident beam toward said liquid surface at an oblique angle thereto, and providing a reflected beam therefrom; a beam expander interposed between said illumination source and said liquid surface for increasing said narrow beam width of said incident beam to a beam width substantially greater than the wavelength of most disturbances in said liquid surface; a filter intercepting a portion of said reflected beam and transmitting therethrough an optical signal of substantially said monochromatic illumination frequency; a converging lens transverse to and intercepting said optical signal from said filter for focusing said optical signal to a centrum; and a beam detector positioned adjacent to said centrum for providing an indication of changes in said level of said liquid surface by detecting corresponding changes in a relative position of said centrum.
Claim 10
Dependent Claim
13 words
The Czochralski furnace of claim 7 wherein said illumination source comprises a laser.
Claim 11
Dependent Claim
13 words
The Czochralski furnace of claim 8 wherein said laser is a HeNe laser.
Claim 12
Dependent Claim
22 words
The Czochralski furnace of claim 7 wherein said incident beam beam width is increased by said beam expander to substantially 16 millimeters.
Claim 13
Dependent Claim
25 words
The Czochralski furnace of claim 7 wherein said beam detector comprises a pair of photodiodes producing a null indication when said centrum falls between them.
Claim 14
Independent Claim
122 words
A method for sensing the level of a liquid surface comprising the steps of: furnishing a source of essentially monochromatic illumination of narrow beam width for directing an incident beam toward said liquid surface at an oblique angle thereto and providing a reflected beam therefrom; expanding said narrow beam width of said incident beam to a bandwidth substantially greater than the wave length of any disturbances in said liquid surface; intercepting a portion of said reflected beam from said liquid surface and focusing said portion of said reflected beam to a centrum; and detecting the position of said centrum and producing an indication of changes in said level of said liquid surface by corresponding changes in a relative position of said centrum.
Claim 15
Independent Claim
122 words
A method for sensing the level of a liquid surface comprising the steps of: furnishing a source of essentially monochromatic illumination of narrow beam width for directing an incident beam toward said liquid surface at an oblique angle thereto and providing a reflected beam therefrom; expanding said narrow beam width of said incident beam to a bandwidth substantially greater than the wave length of any disturbances in said liquid surface; intercepting a portion of said reflected beam from said liquid surface and focusing said portion of said reflected beam to a centrum; and detecting the position of said centrum and producing an indication of changes in said level of said liquid surface by corresponding changes in a relative position of said centrum.
Claim 16
Dependent Claim
18 words
The method of claim 12 wherein said step of furnishing is carried out by means of a laser.
Claim 17
Dependent Claim
19 words
The method of claim 12 wherein said step of expanding is carried out by means of a beam expander.
Claim 18
Dependent Claim
21 words
The method of claim 12 wherein said steps of intercepting and focusing are carried out by means of a converging lens.
Claim 19
Dependent Claim
21 words
The method of claim 12 wherein said steps of detecting and producing are carried out by means of a beam detector.
Claim 20
Dependent Claim
42 words
The method of claim 12 further comprising the step of filtering said portion of said reflected beam prior to said steps of intercepting and focusing and transmitting therethrough said portion of said reflected beam at substantially a frequency of said monochromatic illumination.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-04-01 | 1988-10-01 | 1989-04-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-04-01 | 1992-10-01 | 1993-04-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-04-01 | 1996-10-01 | 1997-04-02 | $7700.00 | Window Closed / Lapsed |