US4018608A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Infra red photography with silver halide films using infrared and visible light exposures
Assignee: Versar Inc
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Filing: 1975-10-10
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Granted: 1977-04-19
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Expires: 1995-10-10
Abstract
Abstract A process for photographing infra red events onto silver halide film including the steps of focusing the infra red radiation directly onto the film to alter the sensitivity of the film to visible light, then flashing the film with a uniform field of visible light at the moment when the sensitivity-altering effect of the infra red is optimum, thereby producing a latent image whose density when developed will vary with the interrelationship between the integrated exposure of the film to infra red and to visible radiation at various discrete areas of the film.
Inventors
- 👤 Gene F. Frazier
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 05:02
CPC Classifications
G; G03; G03C; G03C5/00; G03C5/16; G03C5/164
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
200 words
The method of photographing an infra red event to provide a lasting developable latent image upon a film which is of a visible-light sensitive type having a silver halide grain suspended in an emulsion, comprising the steps of: impinging an image of the infra red event on the film which is initially unexposed to visible light, the infra red exposure being made with sufficient intensity and for an exposure interval sufficient to excite areas of the film which are the most intensely exposed to the infra red beyond the degree of excitation which increases its sensitivity to visible light by merely warming it, to a greater degree of excitation which reduces the sensitivity of the film upon exposure to visible light by reducing the ability of the grain to form a stable latent image in the presence of the excited emulsion; and exposing said film after it has been excited by the infra red and while still excited to a field of visible light whose intensity and duration is such as to produce a developable latent image having, when developed, graduated contrast wherein the densities are functions of the degree of excitation of said areas by the infra red exposure.
Claim 2
Independent Claim
200 words
The method of photographing an infra red event to provide a lasting developable latent image upon a film which is of a visible-light sensitive type having a silver halide grain suspended in an emulsion, comprising the steps of: impinging an image of the infra red event on the film which is initially unexposed to visible light, the infra red exposure being made with sufficient intensity and for an exposure interval sufficient to excite areas of the film which are the most intensely exposed to the infra red beyond the degree of excitation which increases its sensitivity to visible light by merely warming it, to a greater degree of excitation which reduces the sensitivity of the film upon exposure to visible light by reducing the ability of the grain to form a stable latent image in the presence of the excited emulsion; and exposing said film after it has been excited by the infra red and while still excited to a field of visible light whose intensity and duration is such as to produce a developable latent image having, when developed, graduated contrast wherein the densities are functions of the degree of excitation of said areas by the infra red exposure.
Claim 3
Dependent Claim
31 words
The method as set forth in claim 1, including the further step of developing the film to provide an image thereon corresponding with the latent image of the infra red event.
Claim 4
Dependent Claim
36 words
The method as set forth in claim 1, wherein the step of exposing the film to visible light is performed so that it overlaps temporarily the last portion of said interval of exposure to infra red.
Claim 5
Dependent Claim
31 words
The method as set forth in claim 1, wherein the step of exposing the film to visible-light is performed immediately after the end of said interval of exposure to infra red.
Claim 6
Dependent Claim
62 words
The method as set forth in claim 1, wherein the intensity and interval of infra red exposure lie between an upper limit of exposure beyond which the film is damaged such that the effect on the film of the infra red exposure will not fade out as the excitation thereof subsides, and a lower limit where the film is not significantly excited.
Claim 7
Dependent Claim
33 words
The method as set forth in claim 1, wherein the maximum intensity of the infra red radiation does not exceed 10 mw/mm 2 and the interval of exposure does not exceed 12 seconds.
Claim 8
Dependent Claim
40 words
The method as set forth in claim 1, wherein the exposure to visible-light is to a broad band of colors approximating white light, and is of intensity not exceeding 0.3 mw/mm 2 and for a duration not exceeding one second.
Claim 9
Dependent Claim
70 words
The method as set forth in claim 1, wherein the film is black and white film, and the exposure to visible-light is selected such as would increase the density of the film when developed without prior infra red exposure to a uniform gray level intermediate the densities which would result from no exposure of the film on the one hand and full exposure of the film on the other hand.
Claim 10
Dependent Claim
25 words
The method as set forth in claim 1, wherein the exposure to visible-light is to a selected filtered color of light within the visible-light spectrum.
Claim 11
Dependent Claim
63 words
The method as set forth in claim 1, wherein the recited sequence of exposures to infra red and visible-light are preceeded by a preconditioning exposure of the film to the infra red event for an interval at least as long as the recited infra red exposure, and this preconditioning exposure being spaced from said recited sequence of exposures by at least 5 seconds.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-04-18 | 1980-10-18 | 1981-04-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-04-18 | 1984-10-18 | 1985-04-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-04-18 | 1988-10-18 | 1989-04-19 | $7700.00 | Window Closed / Lapsed |