Narrowband Wide Field of View Optical Filter.
DEPARTMENT OF THE NAVY WASHINGTON D C
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A wide angle narrowband optical filter is provided by an assembly in which a body member supports multiple absorption materials in a common optical path. Each of the multiple absorption materials contributes toward narrowing the spectral bandwidth region permitting transmittance of light energy. A bandpass glass color filter restricts light transmission to a relatively broad spectral range of approximately 250 nanometers and a selected coumarin dye material in solution used with a second solution of a selected rare earth material narrows the spectral range of transmittance. In a preferred embodiment an interference filter further narrows the transmitting bandwidth to approximately 12.5 nanometers at FWHM measured at Full Width Half Maximum in the spectral region which is desirably coincident with the wavelengths of light energy best transmitted in ocean waters. Author