UV/IR-Cut / L-Filter 1¼" – CMOS-optimiert

The long story short goes like this: we needed an UV cut filter with a cut-off wavelength in range of 400-420nm. The issue was we needed the filter at an "impossible" size, of precisely 5.6mm diameter. Luckily for us, the 39mm diameter, 0.55mm thick UV/IR cut filter from Baader was thin enough so we could cut it ourselves to measure. Although we do not encourage anybody to cut /shape the filters themselves (it's tedious, highly time-consuming process) the end result was a precise 5.6mm UV cut filter that we could finally mount in our UV fluorescence photography setup. The filter itself performs flawlessly to its purpose but that is quite expected when it comes to Baader filters, right? The results: Attached is an animated GIF. The first shot of a 1000x150 mm rock sample is taken in visible light, the second one in UV light with Baader UV/IR Cut Filter. On the sample there are 3 veins saturated with crude oil. In visible light, those crude oil veins appears dark brown (surrounded by the light grey rock background). In UV fluorescence, the crude oil appears yellowish - brown (while the rest of the rock sample appears deep blue), that is the classic oil UV fluorescence signature. The scans are not actually a single picture, but they were obtained by stitching together slices representing about 5mm of sample (about 200 pictures stitched together to cover the entire 1m length of the sample - our setup does this automatically, virtually in real-time). The third frame of the GIF is a detail picture (mostly purple) that shows how that UV picture would look like WITHOUT Baader UV cut filter. As we can see, the faint fluorescence light we’ve seen in the UV scan is overpowered by the reflected 365nm UV excitation light so a UV cut filter to eliminate the reflected excitation light is critical. Thank you, Baader Planetarium for bringing quality products to the market! P.S.: Attached is also a detail snapshot of the camera setup. The actual camera is the one surrounded by 4 LED (those 4 LEDs are for taking pictures in visible light) while next to the camera there is a black disk made out of ZWB2 (365nm filter) that covers the UV light source (a Nichia 365nm high power UV LED). The overall setup details are available here: https://www.roscientific.com/miniperm.html