A longpass filter or long wavepass filter (LP filter) is one that transmits at longer wavelengths and rejects shorter wavelengths. By design, the transition in a longpass filter between the 50% cut-on to rejection is quite sharp. This makes it much easier to separate excitation from emitted wavelengths without interfering with wavelengths of interest. Long wavepass filters are useful in applications where spectral noise reduction is important or for isolating a particular region of the spectrum.
- Emission filters in fluorescence applications
- Eliminate unwanted radiation over ultraviolet, visible, or infrared
- Ideal for Raman spectroscopy
- Order sorting filters
- Astronomy applications to study IR radiation without visible light
- Laser-induced fluorescence to isolate source radiation