Double layered optical low pass filter permitting improved image resolution

Abstract

A double layered optical low pass filter is provided for use in a color video system for monitoring an object scene. The optical filter is designed to optically complement a dichroic stripe filter to prevent the introduction of spurious signals by any interference between luminance and chrominance signals, while at the same time providing a transmittance of high spatial frequency luminance signal to permit an improved image resolution. The optical low pass filter includes a first phase retarding filter layer designed to provide a first spatial frequency response across the visual spectrum and a second phase retarding filter layer designed to provide a second spatial frequency response across the visual spectrum. The combined resultant optical transfer function of the filter layers disclose a cut off of the higher spatial signal components of the primary color design wavelengths of the respective first and second filter layers, while transmitting a higher spatial frequency for the luminance signal to provide the improved image resolution. The specific cut off spatial frequencies of the primary colors and the bandwidth of the luminance signals can be subjectively optimized for any applicable system.

Dependencies are inferred from the claim text.