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Laser-Stimulated Fluorescence of a Pumpkin

Fluorescence UV Lighting
19 replies to this topic

#1 Andy Perrin

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Posted 17 January 2021 - 04:16

Here is a pumpkin (or in some parts of the world, a squash) using Laser-Stimulated Fluorescence (LSF). LSF was described in my first post on it back here. Please reference that post for the procedure and background, safety requirements, and equipment used.

Camera was the Sony A7S (modified).
Lens was the Nikkor 20mm/3.5 (which I haven't tested in UV reflectance).
Filters on camera were the Tiffen Haze 2E + BG38 2mm.

30 sec, F/16 (for depth of field reasons), ISO400.
White balance altered to suit taste.
Attached Image: _DSC8482 LIF-aurora UVP.jpg

Edited by Andy Perrin, 17 January 2021 - 05:25.


#2 Cadmium

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Posted 17 January 2021 - 05:03

Andy, Very nice! :smile:

#3 colinbm

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Posted 17 January 2021 - 06:59

That seems to be working well Andy.
I wonder if you had two lights working in parallel, either side of the lens, you would get less shadows.

#4 Andy Perrin

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Posted 17 January 2021 - 07:03

Thanks Steve!

Colin, my big problem right now (aside from figuring out how to attach one of those Powell lenses which is turning out to be very hard) is that the light painting is hard to do without leaving bright lines by lingering too long in one spot. I badly need to automate the scanning process with a turntable setup. Dealing with two lasers at once is a problem for some other day!

In this case I actually like the shadows though.

Edited by Andy Perrin, 17 January 2021 - 07:05.


#5 colinbm

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Posted 17 January 2021 - 07:28

Yes I appreciate the shadows give depth & 3D...

#6 Øivind Tøien

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Posted 17 January 2021 - 08:00

+1, and then there is that almost toothless face in there.
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#7 dabateman

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Posted 17 January 2021 - 09:29

Great composition Andy.
Also nice your pumpkin hasn't gone moldy. I assume its not leftover from Halloween.

#8 Stefano

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Posted 17 January 2021 - 12:45

Nice colors. It would be interesting to see if typical UVIVF yields weaker colors.

#9 JMC

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Posted 17 January 2021 - 13:34

Very nice Andy. Looks like a useful approach.
Jonathan M. Crowther

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#10 Andy Perrin

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Posted 17 January 2021 - 15:05

dabateman actually it really is leftover from Halloween. It never rotted so I never threw it out.

Stefano I actually shot a UVIVF also but it’s very similar. Colors are slightly bluer. The intensity isn’t making much difference to the results here because the pumpkin already glows pretty strongly in UV.

#11 Andy Perrin

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Posted 17 January 2021 - 17:18

Here's the UVIVF:
Attached Image: _DSC8480 UVIVF-aurora UVP.jpg

Here's the LSF again for comparison purposes so you don't have to scroll:
Attached Image: _DSC8482 LIF-aurora UVP.jpg

#12 microbat52

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Posted 17 January 2021 - 18:38

oooh so cool!!!

#13 Stefano

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Posted 17 January 2021 - 18:44

I think the LSF has nicer colors. Changing the exitation wavelength can change the emitted colors.

#14 Bernard Foot

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Posted 17 January 2021 - 21:37

That is amazing! Hope you enjoy your pumpkin pie.
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#15 Andrea B.

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Posted 21 January 2021 - 00:10

There is a beautiful unexplored jurassic-jungle-world in there. Dinosaurs might be encountered.

An interesting aspect photographically is the cool reflection (perhaps off aluminum foil?) underneath
which gives the impression that the pumpkin is glowing from inside.
Andrea G. Blum
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#16 Andy Perrin

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Posted 21 January 2021 - 03:00

Yes, it's sitting on aluminum foil, in hopes of reflecting more light inside so it's not all dark.

#17 Andrea B.

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Posted 22 January 2021 - 21:15

Andy, you have a good compositional eye in case I haven't mentioned that before.

For about a year I have been quite lazy about making any UVI fluorescence photos. They can be so cool and dramatic and interesting.
Andrea G. Blum
Often found hanging out with flowers & bees.

#18 Andy Perrin

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Posted 22 January 2021 - 22:07

Thanks!

#19 UlfW

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Posted 23 January 2021 - 12:30

I really like these images and their composition.

I wish I too had time and locations suitable trying UVI fluorescence photos.

Andy, what is the reason for using a laser instead of a high power LED with 405nm?
The line laser idea makes my design mind literally spin with ideas of how to get some scanning of the line over the motif.
I am tempted to get a line laser and do some proof of concept tests of my ideas.

Edited by UlfW, 23 January 2021 - 12:33.

Ulf Wilhelmson
Curious and trying to see the invisible.

#20 Andy Perrin

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Posted 23 January 2021 - 14:55

Ulf these are proof of concept tests for large scale fluorescence on the sides of buildings! I want to do fluorescence at the 10m scale.

I’m actually already working on a turntable idea with a stepper motor.

Also- line lasers with cylinder lenses are a bad choice for this actually. Powell lenses are a must.
Check the paper I linked on the original topic here:
https://www.ultravio...ce-first-tests/

Edited by Andy Perrin, 23 January 2021 - 16:24.