Are cheap UV detection cards any good?

Lasers are also very photogenic for video. Much easier to make a beautiful laser video than magnet video :) I am working on getting some new laser colors in my collection. Will have to make an update video with the my strongest lasers for each wavelength when that happens. The 'old' one is here: https://youtu.be/c4RsQdyjgJE

Light and lasers are so cool. How can anyone turn down more tests with lasers? Maybe some time you can do a video with all your old and new lasers? I would really like that.

Hi Joe. Thanks for sharing. I may be overly cautious with UV but stories like yours reminds me it isn't without reason. The cards are all right for simple detection tasks - except the middle, round one. Just had it out in a sunny day with a max UV index of 5.5. Quite high for Denmark where around 7 is max. It didn't indicate at all even around noon... I think I may have somehow bleached the pigment in it. It does not respond to anything now. Shouldn't be possible since the two others are still fine under the same conditions. So don't buy the round one - it can't be trusted... What detection gear do you have? During the preparations for the video, I was looking at electronic meters that can measure separately in the UVC, UVB or UVA spectrum and in µW/cm2. Found an interesting one with 9 different probe options. Really nice but the whole set would cost over $3,000.... https://www.ebay.com/itm/164174952678 I will stick with a combination of UV cards and the USB spectrometer for now :o)

Interesting. I have had battles with skin cancer, and so limiting UVA and UVB exposure has been important to me. During the early days of COVID, when it was thought that it lived on surfaces far longer than it actually does, I was using a UVC box I built to (pointlessly, as it turned out) disinfect things that were coming into the house. For both purposes, I bought detection gear - one that measures UVA/UVB and one for UVC. I had figured that the cheap test cards would be - well - cheap, and not terribly accurate - and with the UVC, you wanted to be accurate as it requires 3mJ/cm2 to inactivate coronaviruses. It's good to know that they are potentially useful, and presumably far less costly. Pro tip for those of us watching UVA/UVB exposure: All glass filters UVB very effectively, but only safety glass will also filter UVA, and UVA is of primary concern with skin cancer. One place that most people don't think about their exposure is in their cars - and as it turned out, I wound up with a basil cell carcinoma on my left cheek - the one next to the window as I drove. So if you are concerned, make sure that you get UVA-filtering tint for your car windows if they do not have safety glass. You can tell safety glass from regular glass by looking at the edge of the window and looking for two layers with a thin plastic layer in the middle - so basically 3 distinct layers versus only one. I've seen a few cars with safety glass on all windows, but the vast majority only have safety glass used for the windshield (required by law in most places) and on any sunroof, with all side glass being single layer.

Joe Tomasone