Another alternative is to use a 440nm light source and a frequency doubling crystal https://phoseon.com/wp-content/uploads/2019/04/Stable-high-efficiency-low-cost-UV-C-laser-light-source-for-HPLC.pdf although the efficiency is questionable, there are also other variations based on frequency quadrupling https://opg.optica.org/oe/fulltext.cfm?uri=oe-29-26-42485&id=465709.
Another alternative is to use a 440nm light source and a frequency doubling crystal https://phoseon.com/wp-content/uploads/2019/04/Stable-high-efficiency-low-cost-UV-C-laser-light-source-for-HPLC.pdf although the efficiency is questionable, there are also other variations based on frequency quadrupling https://opg.optica.org/oe/fulltext.cfm?uri=oe-29-26-42485&id=465709.