Filtering Technology: Absorptive VS. Interference Filters
Optical filters are used to selectively transmit, reflect, or block different wavelengths of light. Optical filters can be used in a wide range of applications in many industries, including industrial, scientific, and medical. Interference and absorptive filters are the two main types of optical filters used, and they both play crucial roles in military optical systems.
Military Applications of Optical Filters
In military settings, optical filters play a key role in many important aspects of mission effectiveness and safety. Optical filters can be applied to hardware such as displays, touch panels, detectors, cameras, sensors, and more, and can also be used for mapping, tracking, analysis, and navigation. The use of interference filters can support Night Vision compatibility, manage stealth and signal control, and enhance targeting systems. Absorptive filters help with laser protection, camouflage and concealment, and environmental adaptability.Â
Absorptive VS. Interference Filters
Absorptive and interference filters are the two most common types of optical filters used today. Each has different strengths and can be utilized in specific applications suited to the intended use.
Developed through advances in thin-film technology, interference filters are best suited for applications where very precise spectral control is required. Interference filters can be used to make displays compatible with night vision goggles (NVGs), render equipment undetectable to enemy sensors, and improve target identification and tracking. Using multiple layers of dielectric materials, interference filters use constructive and destructive interference to select certain wavelengths to pass through and others to be refracted. Interference filters may require more care and can be more susceptible to humidity and thermal energy damage.
Absorptive filters are often made of dyed glass, pigmented gelatin resins, or synthetic plastic. Military applications for absorptive filters include protecting the eyes and sensors from lasers, enhancing the camouflage capabilities of equipment by concealing light, and adapting optical systems to varying lighting and atmospheric conditions. Absorptive filters result in a wider bandwidth and less precise wavelength selection than interference filters and are generally less expensive to manufacture than interference filters. However, science has improved their performance over time, making them a vital tool for modern display technology and military uses.
Combining interference and absorption filters has benefits in military settings, such as enhancing visual performance, facilitating transitions from day to night, or adapting to changing environmental conditions.
