Filters

Optical filters are lenses that transmit certain wavelengths of light.  There are many different types of optical filters.  Absorptive filters will absorb certain wavelengths of light while letting others through.  Dichroic filters do the opposite of absorptive filters; they reflect certain wavelengths and let certain ones through.  Dichroic filters' films form a sequential series of reflective cavities that resonate with the desired wave lengths. Other wavelengths destructively cancel or reflect as the peaks and troughs of the waves overlap. 

Infrared or heat-absorbing filters are designed to block mid-infrared wavelengths but pass visible light. They are often used in devices with bright incandescent light bulbs to prevent unwanted heating. There are also near-infrared filters which are used in solid state video cameras to compensate for the high sensitivity of many sensors to near-infrared light.  Ultraviolet filters block ultraviolet radiation, but let visible light through.  Neutral density filters have a constant attenuation across the range of visible wavelengths, and are used to reduce the intensity of light by reflecting or absorbing a portion of it. They are specified by the optical density of the filter. 

click here to view filters in our catalog