US3722978A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optical scattering filter with hygroscopic material
Assignee: Beckman Coulter Inc
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Filing: 1971-08-30
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Granted: 1973-03-27
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Expires: 1991-08-30
Abstract
Abstract Long pass optical filters for the infrared region and methods of making the same are disclosed which utilize a transmitting matrix of high and low refractive index materials for selectively scattering all wavelengths shorter than a critical wavelength and which have a relatively sharp cut-on front. By the inclusion of materials having absorption bands at wavelengths longer than the cut-on wavelength of the scattering medium, the cut-on front may be sharpened and positioned over a wide range to provide a filter having a preselected cut-on wavelength and cut-on front. The absorbing materials may include one or more hygroscopic materials whose particles tend to coalesce when finely divided. By adding small quantities of a highly refined mineral oil and mulling before die pressing while heating, these materials may be evenly distributed throughout the area of the filter.
Inventors
- 👤 H Sloane
- 👤 G Keahl
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 11:24
CPC Classifications
G; G02; G02B; G02B5/00; G02B5/20; G02B5/206; G02B5/22
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
89 words
An optical filter having relatively high transmission to infrared radiation comprising: a thin transmitting wafer comprising a microporous material producing selective scattering of all wavelengths shorter than a selected wavelength; and at least one absorbing material having an absorption band coextensive with the shorter wavelength transmission region of said wafer, the particles of said material tending to coalesce when finely divided, said material absorbing at least a portion of the energy transmitted by said wafer and being substantially evenly distributed over an area commensurate with the radiation transmitted thereby.
Claim 2
Dependent Claim
124 words
An optical filter having relatively high transmission to infrared radiation wavelengths longer than a predetermined wavelength comprising the combination of: a thin transmitting wafer comprising a microporous material producing selective scattering and being substantially opaque to all wavelengths shorter than a first wavelength; and at least one absorbing material having an absorption band that is substantially opaque between a first and second wavelength, said second wavelength being shorter than said first wavelength and said third wavelength being longer than said first wavelength, the particles of said absorbing material tending to coalesce when finely divided, said absorbing material being finely divided and substantially evenly distributed over an area commensurate with the radiation transmitted thereby and positioned to absorb radiation between said first and second wavelength.
Claim 3
Dependent Claim
123 words
An optical filter having relatively high transmission to infrared radiation comprising: a polyethylene matrix having micron size pores of substantially uniform diameter substantially evenly distributed therethrough said matrix being substantially opaque to radiation of wavelengths shorter than a first wavelength and having a relatively sharp cut-on front and being highly transmissive to radiation of wavelengths longer than said cut-on front; and at least one absorbing material having an absorption band coextensive with the shorter wavelength transmission region of said matrix and absorbing at least a portion of the energy transmitted by said matrix, the particles of said absorbing material tending to coalesce when finely divided, said material being finely divided and substantially evenly distributed over an area commensurate with the radiation transmitted thereby.
Claim 4
Dependent Claim
147 words
An optical filter having relatively high transmission to infrared radiation comprising the combination of: a first polyethylene matrix having micron size pores of substantially uniform diameter substantially evenly dispersed therethrough, said matrix (i) being substantially opaque to radiation of wavelengths shorter than a first wavelength, (ii) having a relatively sharp cut-on front and (iii) being highly transmissive to radiation longer than said cut-on front; and at least a second matrix having at least one finely divided material the particles of which tend to coalesce, said finely divided material being substantially evenly distributed therethrough and having an absorption band that is substantially opaque between a first and second wavelength, said second wavelength being shorter than said first wavelength and said third wavelength being longer than said first wavelength, said second matrix having no significant absorption bands in the region from said third wavelength to at least 300 microns.
Claim 5
Dependent Claim
134 words
An optical filter having relatively high transmission to infrared radiation comprising: a polyethylene maTrix having micron size pores of substantially uniform diameter substantially evenly dispersed therethrough; at least a second matrix; and a plurality of absorbing materials the particles of at least one of which tend to coalesce when finely divided, said plurality of absorbing materials having overlapping absorption bands of intensity such that the region between a second wavelength and a third wavelength is substantially opaque, said second wavelength being shorter than said first wavelength and said third wavelength being longer than said first wavelength, each of said plurality of absorbing materials being finely divided and substantially evenly dispersed throughout said second matrix, said second matrix having no significant absorption bands in the region from said third wavelength to at least 300 microns.
Claim 6
Dependent Claim
135 words
An optical filter having relatively high transmission to infrared radiation wavelengths longer than a predetermined wavelength comprising the combination of: a thin transmitting wafer comprising a microporous material producing selective scattering and being substantially opaque to all wave lengths shorter than a first wavelength; and a plurality of absorbing materials having overlapping absorption bands of intensity such that the region between a second wavelength and a third wavelength is substantially opaque, said second wavelength being shorter than said first wavelength and said third wavelength being longer than said first wavelength, the particles of at least one of said absorbing materials tending to coalesce when finely divided, each of said absorbing materials being substantially evenly distributed over an area commensurate with the radiation transmitted thereby and positioned to absorb radiation between said second and third wavelength.
Claim 7
Dependent Claim
28 words
An optical filter according to claim 7 wherein: said plurality of absorbing materials include KBr, BaCO3, BaF2, PbCO3 and LiF and said third wavelength is about 86 microns.
Claim 8
Dependent Claim
30 words
An optical filter according to claim 8 wherein: said plurality of absorbing materials include approximately 24.4 mg/in2 of KBr, BaCO3 and BaF2 and approximately 8.2 mg/in2 of PbCO3 and LiF.
Claim 9
Dependent Claim
29 words
An optical filter according to claim 7 wherein: said plurality of absorbing materials include KBr, CsBr, CaCO3, BaCo3, Li2CO3 and BaF2 and said third wavelength is about 135 microns.
Claim 10
Dependent Claim
32 words
An optical filter according to claim 10 wherein: said plurality of absorbing materials include approximately 24.4 mg/in2 of KBr, CaCO3, BaCO3 and BaF2, 65.2 mg/in2 of CsBr and 8.2 mg/in2 of Li2CO3.
References Cited (Backward Citations)
US3228292A
Cited
US3279938A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-03-26 | 1976-09-25 | 1977-03-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-03-26 | 1980-09-25 | 1981-03-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-03-26 | 1984-09-25 | 1985-03-27 | $7700.00 | Window Closed / Lapsed |