Combination optical low pass filter capable of phase and amplitude modulation
AssigneeMinolta Camera Kabushiki Kaisha
InventorsShoichi Ohneda, Yukio Okano
Life of this patent
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Abstract
A combination optical low pass filter adapted for use in a single or double tube color television camera is provided with a phase retarding pattern on a transparent substrate. The pattern includes optical elements having a transmissivity which varies with the wavelength of light passing there through so that the optical low pass filter functions as both a phase diffraction and an amplitude diffraction filter. Medium indexed filler material can further supplement the pattern to eliminate any light scattering.
Claims21
In an optical low pass filter for use in a single or double tube color television camera having a transparent substrate and a plurality of optical elements disposed on the substrate for introducing phase retardation in the light transmitted there through, the improvment comprising;
- the optical elements being formed of material whose transmissivity varies with the spectral band of incident light.
In a single tube color television camera including an image pickup tube having a faceplate and an optical low pass filter having a transparent substrate supporting a plurality of optical elements disposed on the substrate for introducing phase retardation in transmitted light, the improvement comprising;
- each optical element having a plurality of sublayers with adjacent sublayers having different refractive indices, the number of sublayers and respective optical thickness of each layer being selected to make each optical element transmissive for a predetermined spectral band of light.
A combination phase and amplitude optical filter for modulating light in a color television video system comprising;
- a transparent substrate;
- a phase retarding layer connected to the substrate and providing an optical transfer function value characteristic of cutting off the transmittance of high spatial frequency signal components of at least one or more wavelengths while passing at least another wavelength above the cutoff frequencies, the phase retarding layer further includes a plurality of optical elements, each optical element having a plurality of sublayers of respective different indices of refraction, the relative optical thicknesses and index of refraction of each layer is selected to provide a wavelength variance in the transmissivity of light energy passing through each optical element for at least two different bandwidths in the visual spectrum.
Dependencies are inferred from the claim text.