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AssigneeThe United States of America as represented by the United States Department of Energy
InventorMichael C. Rushford
Estimating the term…
A pin hole camera assembly for use in viewing an object having a relatively large light intensity range, for example a crucible containing molten metal in an atomic vapor laser isotope separation (AVLIS) system is disclosed herein. The assembly includes means for optically compressing the light intensity range appearing at its input sufficient to make it receivable and decipherable by a standard video camera. To accomplish this, the assembly utilizes the combination of interference filter and a liquid crystal notch filter. The latter which preferably includes a cholesteric liquid crystal arrangement is configured to pass light at all wavelengths, except a relatively narrow wavelength band which defines the filter's notch, and includes means for causing the notch to vary to at least a limited extent with the intensity of light at its light incidence surface.
In a liquid crystal notch filter configured to pass light at all wavelengths except a relatively narrow wavelength band which defines the filter's notch, the improvement comprising means for causing said notch to vary to at least a limited extent with the intensity of light at its light incident surface, independent of the temperature at that surface.
In a method of filtering light by means of a liquid crystal notch filter configured to pass light at all wavelengths except a relatively narrow wavelength band which defines the filter's notch, the improvement comprising the step of causing the notch to vary to at least a limited extent with the intensity of light at its incident surface.
In a system in which an object having a given light intensity range is viewed, an assembly for compressing said light intensity range comprising means defining an input for receiving the uncompressed light intensity range and an output, and light filtering means located between said input and output responsive to said uncompressed light intensity range for filtering said range in a way which causes the light passing therethrough to display a compressed light intensity range, said filtering means including a thermally responsive liquid crystal notch filter and an interference filter positioned in serial relationship with one another with the liquid crystal notch filter being disposed in front of said interference filter, said notch filter being configured to pass light at all wavelengths except a relatively narrow wavelength band and including means for causing said notch to vary to at least a limited extent with the intensity of light at its incident surface.
Dependencies are inferred from the claim text.