Longpass Filters

Edge filters separate a broad spectrum of light into two components: a transmitted component and a rejected component. Long wave pass edge filters (longpass filters) have a region of rejection on the short-wavelength side of the cut-on wavelength. These filters are defined by a cut-on slope establishing the transition between a region of high rejection and a region of high transmission that is provided by thin-film coatings or absorptive colored glass. Long pass filters are useful in a variety of applications ranging from clinical chemistry analyzers to grain harvest process control and can be used with shortpass filters for custom bandpass filtering.