Optical Filters

Optical filters control which wavelengths or optical power levels reach a detector, image plane or downstream component. The range includes narrowband and colored-glass bandpass filters, longpass and shortpass edge filters, reflective and absorptive neutral-density filters, variable attenuators, and dichroic thermal filters that separate visible and infrared energy. Product families are grouped by spectral function so passband, cutoff and attenuation requirements can be compared before model selection.

Define the required transmitted band, rejected band and allowable optical density first. For bandpass products, compare center wavelength, full width at half maximum and out-of-band blocking; for edge filters, compare cutoff position and transition slope; for neutral-density products, verify optical density uniformity and usable spectral range. Interference filters are sensitive to angle of incidence and polarization, so systems operating away from the catalog angle should be reviewed before purchase.