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UVB 309nm in Various Fluorescence

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#1 colinbm

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Posted 14 July 2021 - 13:40

Up-graded the UVB 309nm LED light to 12 LEDs with 40 watts of power. With a second one to finish tomorrow.
Following is a variety of photos of various UVB 309nm induced fluorescence.

First is a picture of the new set-up with U325c filter glass.

Attached Image: 2021 07 14-1, 40w UVB 309nm LEDs with 5mm U325c.jpg


Second is Three Rocks in Visible Light.

Attached Image: 2021 07 14-2, Three Rocks in Visible light.jpg


Third is Three Rocks in UVB 309nm Induced Visible Fluorescence.

Attached Image: 2021 07 14-3, Three Rocks in UVB I Vis Fluor.jpg


Fourth is Three Rocks in UVB 309nm Induced 410nm to 1000nm Fluorescence.

Attached Image: 2021 07 14-4, Three Rocks in UVB I 410nm+ Fluor.jpg


Fifth is Three Rocks in UVB 309nm Induced UVA (Baader U filter on Camera) Fluorescence.

Attached Image: 2021 07 14-5, Three Rocks in UVB 309nm I UVA Fluor processed in PN.jpg


Sixth is Three Rocks in UVA 365nm Induced Visible Fluorescence.

Attached Image: 2021 07 14-6, Three Rocks in UVA I Vis Fluor.jpg

#2 Stefano

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Posted 14 July 2021 - 13:50

40 Watts of power, that a powerful UVB LED lamp!

The middle rock (blue in visible light) seems to change a lot between UVA and UVB. The rock on the right looks almost the same.

#3 colinbm

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Posted 14 July 2021 - 14:01

Thanks Stefano
I'll have two tomorrow :smile:
I might do the rocks again but individually.

#4 JMC

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Posted 14 July 2021 - 14:46

Hi Col, I did some fluorescence of Yooperlite changing the wavelength of UV I used and looking at how the visible fluorescence changed. For the middle rock especially, I got a similar effect to you - redder and darker at 310nm vs longer wavelength UVA.

The thread is here - https://www.ultravio...dpost__p__39656
Jonathan M. Crowther

http://jmcscientificconsulting.com

#5 colinbm

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Posted 14 July 2021 - 14:52

Thanks Jonathan
The middle blue rock I know, it is Sodalite.
Yes Yooperite, looks nice, I haven't seen one yet.

#6 photoni

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Posted 14 July 2021 - 16:04

the central rock in the last photo looks incandescent

#7 dabateman

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Posted 14 July 2021 - 18:01

You might actually have some UVBiUVAF (uvb induced UVA fluorescence) in that middle rock.
That will be a first here.
Very cool.

#8 colinbm

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Posted 14 July 2021 - 20:31

Thanks Toni & Thanks to Dave for suggesting the UVB I UVA Fluor.
It will be interesting to see how this develops & finding other reactions in this region.

#9 colinbm

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Posted 15 July 2021 - 03:10

I am looking for a filter that cuts off before the BaaderU say 320nm & transmits below 300nm, that is passes UVB & below.

#10 dabateman

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Posted 15 July 2021 - 04:18

The only one available I know of now is the invisible vision 308nm filter.
Its very expensive
http://www.invisible...ion_-_308nm.pdf

Jonathan tested it here:
https://www.ultravio...r-skin-imaging/

Edited by dabateman, 15 July 2021 - 04:23.


#11 colinbm

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Posted 15 July 2021 - 04:31

Thanks for both of these Dave, appreciated.

#12 Fandyus

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Posted 15 July 2021 - 12:29

View Postdabateman, on 15 July 2021 - 04:18, said:

The only one available I know of now is the invisible vision 308nm filter.
Its very expensive
http://www.invisible...ion_-_308nm.pdf

Jonathan tested it here:
https://www.ultravio...r-skin-imaging/
The transmission in the PDF seems a bit too optimistic.

#13 Andy Perrin

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Posted 15 July 2021 - 17:52

View PostFandyus, on 15 July 2021 - 12:29, said:

The transmission in the PDF seems a bit too optimistic.
Don't know why you'd say that, it compares pretty closely to what Jonathan measured.

#14 dabateman

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Posted 15 July 2021 - 18:47

Yes Jonathan's 55% transmission is insignificantly different than the pdf 60% transmission.

Even if the real transmission was 40%, you still couldn't really tell the difference on a camera for one that would be 60%.
1 stop difference would be 30%, 2 stops is then down to 15%.

So if the tested filter was 60% transmission at 1 second. Than a 30% transmission one would need 2 seconds exposure. At 50 to 55%, your less than a 1/3 stop and your exposure would be more impacted by the distance of your light source or the angle of the sun light.

#15 Fandyus

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Posted 15 July 2021 - 20:19

I think a lot of those would look a lot better with some white balancing. Might make them less scientifically accurate but at least everything won't be swamped in blue.

#16 Fandyus

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Posted 15 July 2021 - 20:20

View PostAndy Perrin, on 15 July 2021 - 17:52, said:


Don't know why you'd say that, it compares pretty closely to what Jonathan measured.
Well I said that because that would imply the filter doesn't leak at all


#17 Andy Perrin

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Posted 15 July 2021 - 20:37

View PostFandyus, on 15 July 2021 - 20:20, said:

Well I said that because that would imply the filter doesn't leak at all

Nope, it does not imply that. The problem is that the scale in both Jonathan's graph and the PDF's graph are linear scales, but our cameras and eyes are logarithmic. On a linear scale, you can NEVER read the OD of blocking for out of spectrum stuff. It's just too small to be visible unless the leakage is huge. This is why we use log or diabatic graphs when we want to show that information. The graph in the PDF is not misleading provided you understand that linear graphs all have this limitation.

Edited by Andy Perrin, 15 July 2021 - 20:37.


#18 Stefano

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Posted 15 July 2021 - 20:43

Also seeing UVB in sunlight, as Jonathan said, is not easy. OD 4 isn’t enough.

With the above I mean that even if you have a good blocking (like OD 4), a filter may still leak.

Edited by Stefano, 15 July 2021 - 20:50.


#19 Fandyus

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Posted 15 July 2021 - 20:50

View PostAndy Perrin, on 15 July 2021 - 20:37, said:



Nope, it does not imply that. The problem is that the scale in both Jonathan's graph and the PDF's graph are linear scales, but our cameras and eyes are logarithmic. On a linear scale, you can NEVER read the OD of blocking for out of spectrum stuff. It's just too small to be visible unless the leakage is huge. This is why we use log or diabatic graphs when we want to show that information. The graph in the PDF is not misleading provided you understand that linear graphs all have this limitation.
Oh, I see, thanks for explaining.

#20 OlDoinyo

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Posted 16 July 2021 - 03:30

I think Yooperlite and sodalite are the same thing.

There seems to be more light in these frames than mere fluorescence from the rocks. It appears that ambient light might be reflected.