Longpass filters are commonly used to isolate regions of a broad spectrum. The role of this type of filter is to transmit energy over a specified band at wavelengths longer than the cut-on wavelength, and to block the transmittance of energy at wavelengths shorter than the cut-on wavelength. In addition, longpass filters are useful for custom bandpass filtering by using with shortpass filters. Asahi Spectra offers a wide variety of longpass filters in the broad wavelength range: ultraviolet, visible, or infrared wavelengths.