The CVA-14 uses two, 2-channel polycarbonate filter wheel synchronously rotated front and rear of a standard PVS-14.
As the front filter wheel spins, it sequentially passes light through each of its two channels into the PVS-14’s objective lens where it is focused onto the image intensifier’s photocathode. In the intensifier (as it normally does), the photocathode converts the light into electrons, which is then amplified by the intensifier’s microchannel plate and then directed to the intensifier’s phosphor screen. That phosphor screen produces a visible light image composed of mainly green and blue light plus a small amount (6%) of red light which is viewed through the rotating 2-Channel rear filter wheel.
The front filter wheel has one channel with a specialized Gemini filter that passes both short wave and selected IR wavelengths of light, and a second unfiltered channel that passes all wavelengths.
The rear filter wheel has one unfiltered channel that passes all wavelengths of light, and a second filtered channel that passes only red wavelengths.
The front filter wheel is synchronized with the rear filter wheel so that:
- when the front wheel’s SWP channel is in front of the objective lens, the rear wheel’s clear section is behind the PVS-14’s eyepiece and passes blue and green light and that small amount of red light;
- when the front wheel’s unfiltered channel is in front of the objective lens, the rear wheel’s red filter section is behind the PVS-14’s eyepiece and passes only red light.
In this way, the two Gemini channels sequentially encode the color information from the scene, which is then amplified by the PVS-14, and then presented to the user’s eye in a way that the brain and human visual system can decode the color information and use it to create for the user a full color image down to starlight light levels.