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UltravioletPhotography

Differentiating sunscreen ingredients with UVA and UVB fluorescence photography


JMC

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I've been thinking about using UVA and UVB fluorescence photography to differentiate between sunscreen ingredients with different UV absorption characteristics.

 

EDIT 15/2/19 - For reasons I can't go into here, I have had to update my work and have based it the effects of different sun filters have when blocking UVA and B and preventing the fluorescence of a substrate behind them. This was done using a standard EOS 5DSR camera, and involved filtering the light source with either a Baader U filter (UVA illumination) or Invisible Vision 308nm filter (UVB illumination). Doing that I could differentiate the two sunscreens based on how they absorbed the UV light in the 2 regions. The link to the work is here;

 

https://jmcscientificconsulting.com/differentiating-sunscreen-ingredients-with-uva-and-uvb-photography/

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Jonathan,

Thats a very detailed interesting story/test. I would have thought you may wanted to hide some of the specifics before being hired by a company. As your idea of sunscreen lifetime and residuals is an interesting one. Could be a way to improve formulation.

I see about the same 2 stops less exposure at 313nm than 365nm. Your light source does have great 297nm and 302nm Hg lines. For 313nm and 335nm the commercial UVb reptile lights output alot. Enough for me to see 335nm using the Sd14.

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Hi David, My research area is methods - the techniques themselves - so with the write up the aim was to share the approach and emphasise the complexity from a simple question. Even with that write up, there were a few things I didn't go into in detail though, and the equipment required is stuff I have but isn't likely to be found in most labs, nor is the imaging expertise these days. Most specialists tend to have been laid off, as they don't fit the normal corporate employee models.

Good to see you get similar exposure difference between 313nm and 365nm. I thought it was going to be a much bigger difference than 2 stops. I must try it with my normal multispectral camera at some point and see if that is different to the monochrome one.

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