Optical Cast Infrared (IR) Longpass Filters are ideal for blocking visible light while passing near infrared wavelengths. New plastic technology has produced filters with properties that can satisfy a variety of optical and environmental needs at half the weight of glass filters. Compared to similarly available transparent plastics, Thermoset ADC filters have the highest transmission and lowest haze, have at least 25-50 times greater abrasion resistance, and are resistant to all types of chemicals and solvents (acetone, acids, alkali, and alcohols). Optical Cast Infrared (IR) Longpass Filters have excellent thermal characteristics and are resistant to pits from hot sparks resulting from welding or grinding processes. The filters can also be easily drilled with high-speed carbide bits for all mounting types.