Optical Filters

To achieve NVG compatibility of military equipment, the use of night vision optical filters is essential to remove infra red emissions which would otherwise shut down or bloom the NVGs.

Variations include:

• absorptive filters: absorb selected wavelengths of light into the filter (ie infra-red) while the remaining wavelengths are transmitted.
• interference or dichroic filters: use interference to both transmit and block specific wavelengths of light. The unwanted light is reflected back out of the filter enabling only the required light to pass through. The interference properties are provided by a thin film coating of alternate layers of high and low refractive index material, applied in-house in our coating facilities.
• anti-reflective filters: have a coating that is designed to reduce reflection off the front surface of the glass