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Examples of UV-induced Fluorescence

Fluorescence
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#1 nfoto

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Posted 14 April 2013 - 13:03

The aim of this short introduction to the field of UV-induced fluorescence visible to the eye (abbreviated UVIFL or more precisely, UVIVFL) is just to show how diversified and wide-spread these phenomena are. Have a look around you in the kitchen or living room, and you are almost guaranteed to find something that will show nice fluorescence when you shine UV light onto them.

You are not required to use UV-capable lenses in order to record fluorescence as this is manifested in the visible range. However, a filter blocking ultraviolet is required so as not to let UV overpower the appearance of the fluorescent object.

On my way into the downtown discotheque, I was halted by the bouncer who would not let me bring my camera (a D2X with a 50 mm f/1.2 Nikkor lens) into the premises. I snapped a picture of him in a dark alley where the blacklights from the disco inside spilled out, and left the building. Flourescence here is caused by the addition of optical brightening agent to many commercial fabrics.

Attached Image: BOUNCER_C0509080045_FL.jpg
Image reference: BOUNCER_C0509080045_FL.jpg
Nikon D2X, 50 mm f/1.2 Nikkor lens, blacklight leaking from discotheque inside.

Official documents such as money notes and passports virtually always have fluoresceing material embedded in them for reasons of security and to prevent forgery. Expose them to a UV Blacklight and they light up with greenish colours revealing hidden text or symbols.

A watch and money note exposed to blacklight. The security and anti-forgery symbols are brightly visible. The watch has had small amounts of fluorescent paint added to the numerals and the pointers.

Attached Image: NOTE_AND_WATCH_B000114133_UVIFL.jpg
Image reference: NOTE_AND_WATCH_B000114133_UVIFL.jpg
Nikon D1, Nikkor 85 mm f/2.8 lens, Kodak 2E filter, Sylvania Blacklight.

Attached Image: PASSPORT_I0708125671_UVIFL.jpg
Image reference: PASSPORT_I0708125671_UVIFL.jpg
Nikon D200, UV-Nikkor 105 mm f/4.5 lens, Baader UV/IR Cut filter to block non-visible light, Nichia UV-LED torch.

Postal sorting machines are helped in the handling of mail by fluorescent paint on the envelopes. This indicates the zip-code and other relevant information. This kind of fluorescence often appears in orange or red hues.

Attached Image: LETTER_ZIPCODE_I0708125668_UVIFL.jpg
Image reference: LETTER_ZIPCODE_I0708125668_UVIFL.jpg
Nikon D200, UV-Nikkor 105 mm f/4.5 len, Baader UV/IR Cut filter to block non-visible light, Nichia UV-LED torch.

Eggs exhibit a beatuful ruby red to light magenta fluorescence, which likely originates from porphyrine. The darker browhish-coloured fluorescence can be from iron porphyrine. These egg are of the brownish variety. White eggs can emit blue fluorescence. The packing case in the picture below evidently had been treated with optical brighteners so fluoresced brightly in a cold cyan hue.

Attached Image: EGGS_T0802286597_UVIFL.jpg
Image reference: EGGS_T0802286597_UVIFL.jpg
Nikon D200, Coastal Optics 60 mm f/4 APO lens, Baader UV/IR Cut filter, Nichia UV LED torch.

Plastic material sometimes fluoresce in bright colours such as in the scene depicted below. One also readily appreciates that UV fluorescence can help detect remnants of food on the dinner plate.

Attached Image: DINNER_J0801146314_UVIFL.jpg
Image reference: DINNER_J0801146314_UVIFL.jpg
Nikon D200, Coastal Optics 60 mm f/4 APO lens, Baader UV/IR Cut filter, Nichia UV LED torch.

Tonic water contains quinine and fluoresces brightly in cold cyanish blue under UV light

Attached Image: FLOW_T1111057698_UVIFL.jpg
Image reference: FLOW_T1111057698_UVIFL.jpg
Nikon D3S, Voigtländer APO-Lanthar 125 mm lens, in a completely darkened room with Nichia UV LED torch as the only light source

Many more examples can be discovered if you shine a UV light onto household objects. Just remember to don UV-protective goggles as prolonged exposure to direct UV is dangerous to human vision.

[Published 14 Apr 2013]

#2 Nico

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Posted 11 June 2013 - 08:01

You mention the Baader UV-IR cut filter to ensure that the camera is only capturing visible light that is emitted by fluorescence.
I guess that you do also put some filter in front of the UV-torch to reduce / remove the
visible light that is emitted by the torch. What filtration do you recommend for that? – Is a Schott UG11 sufficient?
I’m also wondering what white-balance setting is most appropriate for fluorescence photography.
Thanks, Nico

#3 nfoto

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Posted 11 June 2013 - 08:31

I normally use a Kodak 2E or equivalent. It is a clear filter with a slight yellow ('straw') coloured cast to it.

As to white balance, UVIFL (UV induced visible fluorescence) by definition is in the visible range so any setting for daylight will be OK. There are fluorescence standards (LabSphere supplies them) to use for a colour balance. However, they are expensive and as long as the outcome is similar to what you observe I will not bother. Thus, if you see the deep ruby red fluorescence from chlorophyll, the picture ought to show the same.

#4 Nico

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Posted 11 June 2013 - 09:24

Since the Kodak 2E is UV absorbing, I guess you put it on your lens, not in front of the torch ...?

#5 nfoto

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Posted 11 June 2013 - 10:07

That is 100% correct.

#6 Akira

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Posted 11 June 2013 - 13:59

Hi, Nico, I attach 1.25" version of Baader U onto my Tank 007 torch via BORG 1.25" to C-mount adapter which fits right around the head of the torch. It cuts the visible portion. It is known to pass a slight amount of IR, but, since the light source is LED, the amount of the emitted IR portion should be well negligible:

Attached Images

  • Attached Image: _DSC2273a.jpg

Edited by Akira, 11 June 2013 - 14:06.


#7 nfoto

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Posted 11 June 2013 - 14:49

That is a neat solution, Akira.

Still necessary to work in near darkness, though.