Colored glass filters & sets
Colored glass filters are unique in their ability to transmit a very broad band of light. The long wave pass type, often used as order/wavelength sorting filters, transmit the longer wavelengths and absorb the shorter wavelengths. The bandpass type, useful for enhancing the signal-to-noise ratio of illumination systems, transmit a broad band of energy while blocking the shorter and longer wavelengths. As with all optical components, colored glass filters should not be exposed to high temperatures or sharp temperature changes.
Andover offers two filter sets for verifying the transmittance and absorbance scales of visible absorption spectrophotometers with maximum bandwidths of 2.2nm and 6.5nm. Made of uncoated Schott NG-4 and NG-5 glass, the filters are polished over the central 5mm x 20mm area to a transmitted wavefront of 1/4 wave or better at 633nm and parallelism of 30 arc seconds or better. The transmission value of each filter is measured on a spectrophotometer calibrated with standards directly traceable to the National Institute of Standards and Technology (NIST).