cut-on filter

Optical device that only permits the transmission of radiation of wavelengths shorter than a specified wavelength.
Note:
Although more rare than the cut-off filters, there are a few cut-on filters on the market.
Source:
PAC, 2007, 79, 293 (Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)) on page 319