UV-Induced Infrared Fluorescence Investigation

[Andrea B.]

Last Update: 27 Nov 2017 10:43 GMT-4: Added goal statement. Clarified experiment statement.

 

GOAL TWO

Investigate infrared fluorescence of Spectralon® and PTFE. Do these materials fluoresce in infrared under UV illumination? And, when used for UVI infrared fluorescence photography, do the Schott RG 715/780/830 (2mm) filters on the lens pass any UV from the torch illumination?

 

EXPERIMENT 1 for GOAL TWO

Make UVI infrared photographs of the still life. Test for UV and UV/Vis leakage by the IR-pass filters.

Note: A 'forced exposure' is one having an exposure time much longer than what might reasonably be expected under the given illumination. Because there is no UVI infrared standard by which to estimate exposure time in UVI infrared photographs, I have arbitrarily chosen exposure times of 15" and 30".

• Make Visible reference photo, if needed.
  

• Make a UV-induced infrared fluorescence photo under filtered UV-Led Torch illumination with the Schott RG 715/780 (2mm) on the lens.
  

• Stack the BaaderU UV-Pass filter onto the RG filter. Shoot at the ordinary exposures. Then make forced exposures to force UV light leak (if any). Note that the transmittance charts for the Schott RG filters do not indicate UV light transmission for 2mm thicknesses.
  

• Stack the Schott S8612 (3.5mm) onto the RG filter. Shoot at the ordinary exposures. Then make forced exposures to force UV/Visual light leak (if any).
  

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Visible Reference Photo

White balance and colour profile were applied in Photo Ninja.

 

UV-Induced Infrared Fluorescence Photos: Schott RG 715 (2mm) Red+IR-Pass

White balance and a colour profile were applied in Photo Ninja. No other edits.

 

UV-Leak Test Photos: Schott RG 715 (2mm) IR-Pass

 

UV-Induced Infrared Fluorescence Photos: Schott RG 780 (2mm) IR-Pass

White balance and a colour profile were applied in Photo Ninja. No other edits.

oh la, I misplaced the cropping frame!

[Cadmium]

See, you are better at this than I am. But we knew that.

I might try one shot with just the Spectralon and PTFE, and maybe the original bricks, only to eliminate the IR fluorescing from the bright objects from being any possible added IR illumination on the targets.

[Andrea B.]

I'm so weirded out because I did not get the same results in the controlled experiments/photographs as in my initial photographs !!! I think perhaps that is because in the initial photographs, the UV-Led was held much closer to the Spectralon disk during the forced exposure?

 

Yes, I am def going to re-shoot the disk-on-bricks scene. Plan: Photograph the disk against the dark background. Photograph the bricks alone. Photograph the disk against the bricks. Include the Target-UV strip?

[Cadmium]

These shots work for me, I think the main difference is that these include the more fluorescent objects.

If you re-shoot the original test, you could remove all the really fluorescent object and maybe include more of the Spectralon targets.

[Cadmium]

Kind of cool :-)

 

Lid label:

 

 

[Cadmium]

Here I have tried to duplicate your original settings, using Spectralon White 99% (bottom left) and Black 2% (top left) disks, and PTFE (right side), Krylon 1602 Ultra Flat Black paint (darker background).

ISO 400, Kuribayashi 35mm lens, f/3.5 all shots.

 

Visual. Aperture Priority mode.

 

UVIVF, KV418 on lens, U-340 filters Nichia light. Aperture Priority mode.

 

UVIIRF, RG715 on lens, U-340 filters Nichia light. 10 seconds, Manual Exposure mode.

 

UVIIRF, RG850 on lens, U-340 filters Nichia light. 10 seconds, manual exposure mode.

[Cadmium]

Oops! Just now noticed, your original exposures were 30 seconds, and these I did with 10 seconds. I had 10 seconds in my mind at the time for some reason. Sigh...

[Andrea B.]

Here it is 2 years later. I would like to point out that in my original experiment, those bricks were fluorescing. I'm not entirely sure why this was not mentioned in some kind of conclusion to this long topic. I placed some mentions of this throughtout the topic because apparently at that time I did not realize the bricks were fluorescing. Most bricks don't fluoresce. But my fireplace bricks were recycled and some had some "stuff" on them. Paint maybe? I don't really know.

 

So, in conclusion, Spectralon does not fluoresce, but Andrea's fireplace bricks do fluoresce.

 

OK, done.