Optical Shortpass Filters block or cut-off incoming longer wavelength light by either absorption or reflection, while allowing light below the designed cut-off wavelength to transmit through the optic.
Shortpass filters are characterized by their “cut-off” wavelength, which is the wavelength at the 50% point along the transmission slope.
Shortpass filters are commonly used to block infrared light from interfering with color camera sensors. They can be used along with Longpass Filters to create custom Bandpass Filters.