US3665191A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Filter for compensating efficiency differences in an optical system
Assignee: University of Toronto Innovations Foundation
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Filing: 1969-11-28
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Granted: 1972-05-23
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Expires: 1989-11-28
Abstract
Abstract A compensating filter for use in a registered position at an optical plane in an optical system having differences in efficiencies such that energy from a uniform source creates light of varying intensities over the area of the optical plane, the filter comprising a film negative produced by exposing the film while in registered position at the optical plane to a uniform source through the preceding elements of the system and then developing the film so that its density variations match the variations in light intensities arriving at the optical plane over the area thereof, the negative having its greatest density where the light intensity was greatest and vice versa whereby energy from a uniform source after being translated through the system and film negative emerges as substantially uniform light.
Inventors
- 👤 Norman Frank Moody
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 15:32
CPC Classifications
G; G01; G01T; G01T1/00; G01T1/16; G01T1/161; G01T1/164; G01T1/1641; G01T1/1645; G02; G02B; G02B5/00; G02B5/20; G02B5/205
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
98 words
A compensating filter for use in a predetermined registered position at an optical plane in an optical system having differences in efficiencies such that energy from a uniform source creates light of varying intensities over the area of such optical plane said filter being characterized in that it has varying light transmission characteristics over its area which substantially inversely match the variations in light intensities from a uniform source over the area of the optical plane with which the filter is adapted to register whereby light transmitted from a uniform source through the system and filter is uniform.
Claim 2
Dependent Claim
98 words
A compensating filter for use in a predetermined registered position at an optical plane in an optical system having differences in efficiencies such that energy from a uniform source creates light of varying intensities over the area of such optical plane said filter being characterized in that it has varying light transmission characteristics over its area which substantially inversely match the variations in light intensities from a uniform source over the area of the optical plane with which the filter is adapted to register whereby light transmitted from a uniform source through the system and filter is uniform.
Claim 3
Dependent Claim
51 words
A compensating filter as claimed in claim 1 in which said filter comprises a film negative having varying densities over its area which correspond to the variations of light intensity over such optical plane area created by a uniform source, being greatest where the light intensity is greatest and vice versa.
Claim 4
Dependent Claim
100 words
A compensating filter for a gamma ray camera for use in a registered position at an optical plane in the camera system having at least one phosphor screen and at least one photocathode in advance of such plane, said compensating filter having areas of different light transmission characteristics which inversely correspond to the cumulative efficiency of the preceding phosphor screen and photocathode element areas directing light from a uniform intensity energy source to impinge on such filter areas whereby said filter produces a substantially uniform light intensity output when a uniform light producing energy source is directed onto the camera.
Claim 5
Dependent Claim
100 words
A compensating filter for a gamma ray camera for use in a registered position at an optical plane in the camera system having at least one phosphor screen and at least one photocathode in advance of such plane, said compensating filter having areas of different light transmission characteristics which inversely correspond to the cumulative efficiency of the preceding phosphor screen and photocathode element areas directing light from a uniform intensity energy source to impinge on such filter areas whereby said filter produces a substantially uniform light intensity output when a uniform light producing energy source is directed onto the camera.
Claim 6
Dependent Claim
55 words
A compensating filter as claimed in claim 3 in which said filter comprises a film negative having areas of different densities which inversely correspond to the cumulative efficiencies of the areas of the preceding phosphor screen and photocathode elements causing light of different intensities from a uniform energizing source to impinge on such film areas.
Claim 7
Dependent Claim
105 words
In a gamma ray camera having at least one phosphor screen and one photocathode which because of the differences in efficiencies of areas of such elements produce non uniform light intensities over an optical plane area when the camera is energized by a uniform source, a compensating filter located at said optical plane and having non uniform light transmission characteristics over the area thereof which inversely correspond to such non uniform light intensities created by a uniform source impinging on said optical plane whereby the light output of the filter in response to a uniform source is substantially uniform in intensity over its filtering area.
Claim 8
Dependent Claim
105 words
In a gamma ray camera having at least one phosphor screen and one photocathode which because of the differences in efficiencies of areas of such elements produce non uniform light intensities over an optical plane area when the camera is energized by a uniform source, a compensating filter located at said optical plane and having non uniform light transmission characteristics over the area thereof which inversely correspond to such non uniform light intensities created by a uniform source impinging on said optical plane whereby the light output of the filter in response to a uniform source is substantially uniform in intensity over its filtering area.
Claim 9
Dependent Claim
57 words
In a gamma ray camera as claimed in claim 5 in which said filter comprises a film negative having a non uniform density which corresponds to the non uniform light intensities created by a uniform source impinging on said optical plane having its greatest density at the area where the light intensity is greatest and vice versa.
Claim 10
Dependent Claim
37 words
In a gamma ray camera as claimed in claim 6 a discriminator and a gAting circuit for controlling an optical system subsequent to said optical plane, said discriminator being arranged to sample light output from said filter.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-05-23 | 1975-11-22 | 1976-05-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-23 | 1979-11-22 | 1980-05-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-23 | 1983-11-22 | 1984-05-23 | $7700.00 | Window Closed / Lapsed |