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UltravioletPhotography

Visually Induced Infrared Fluorescence


Cadmium

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I had to try this. :-)

I just tested VIIRF (visually induced infrared fluorescence)

It works!

Here is a quick example.

This is a 'cottage cheese sized' container with some clay scraps in it.

These scraps are dry, unfired, broken bits of extruded clay tubing with a thin layer of colored slip on them (engobe).

There are various engobes on the surface of these clay bits, all of which are colored with different oxides/stains,

some of these have zirconium encapsulated cadmium in them (a glass frit colored with cadmium).

Cadmium is used for red, orange and yellow colors, but is quite toxic, that is why it is encapsulated in zirconium.

These engobes are about 30/60 stain/clay, so the fluorescence would be much stronger if the actual stain were shot alone.

The clay is about 25/25/25/25 kaolin/feldspar/silica/ball-clay, and you can see what it looks like alone by looking at the broken edges of the clay tubes.

Incidentally, the yellow engobe seen in the visual shot is not colored with cadmium, it is a vanadium/praseodymium yellow stain, and it doesn't fluoresce.

 

For this test I 'painted' with a flashlight with an incandescent bulb for the IR, the same flashlight filtered with S8612 3mm for the VIIRF,

and an overhead ceiling light for the visual shot (which was turned off for the other two shots).

The lens has BG38 filter for the Visual shot, and Schott RG850 for the IR and VIIRF shots.

The VIIRF shot required a 30s exposure at 1600 ISO, and probably could have used more.

 

Stains:

http://www.masoncolo...amic_stains.asp

 

Just a quick test.

This makes me wonder if the fired clay will also fluoresce, which I will try soon.

 

Keep in mind that there is no reflected IR light in the VIIRF shot, all IR light is blocked by the S8612 filter on the flashlight, what you see is only visually induced IR fluorescence.

post-87-0-13614400-1458133538.jpg

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In the past I have used Greenockite (naturally occurring cadmium sulphide) to test for visible induced IR luminescence.

Excitation with 540nm light produces a nice fluorescence from around 600nm to 875nm ( I have an emission spectrum somewhere and will post it if I can find it).

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Super cool, Steve !!!!

 

Thanks so much for this investigation. And I hope to see more given that you have access to all those interesting pigments.

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Thank you. Yes, Shane, please post that, thanks.

 

Here are more tests.

I have added a strip of glaze fired to cone 10 (2380F, 1304C).

The firing vitrifies the clay, colors, and clear glaze, this brings out the visual color more, and obviously does the same with the fluorescence.

 

1) At the top is some of the cadmium stain powder.

2) At the left is a fired strip of engobes containing various stains, including some cadmium colored engobes, this is fired with a clear glaze.

3) At the center and lower is an unfired construction of scrap tubing with various colors.

post-87-0-28572800-1458192774.jpg

 

Various fired tubes, with various engobe colors, some colored with cadmium, all are fired with a clear glaze which has fused all the tubes together as stacked together in the kiln.

Basically, anything that glows white in this VIIRF shot is cadmium.

post-87-0-91297300-1458192819.jpg

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Andy Perrin
These are really interesting! Also, it seems fitting that the cadmium is what gives such strong results. :P
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Lovely to see these examples from the clay bugle factory. The stain powders look fantastic in all the different lights.

Have you done these in UVA & UVIVF ?

Col

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Have you done these in UVA & UVIVF ?

Col

 

UVA has nothing interesting, mostly black with some lavender/blue on the visually lavender/blue areas.

No UVIVF with these.

 

VIIRF is easy to do.

Full Spectrum or IR converted camera. I used the kit lens, 18-55mm VR.

Some visual light source, or even green light source, filtered with BG glass or visual only filter that suppresses all IR.

Various IR longpass filters on the lens, I like RG850, but you can use any longpass IR filter in a range from about 700nm up to even 1000nm.

Long exposure time / high ISO. Pre-auto-focus lens using unfiltered light, turn off auto-focus, and shoot with BG filtered light.

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If anyone knows of other materials that fluoresce in IR please post them here.

 

I attempted some UV-induced IR fluorescence with a Silver Cinquefoil flower.

Scroll down to the 6th photo made with the 820nm filter.

http://www.ultravioletphotography.com/content/index.php/topic/855-potentilla-argentea-silver-cinquefoil-more-examples-and-fluorescence

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Very cool Cadmium

 

I wonder what a set comparing these would look like with recorded light starting at 590nm-720nm instead of 850nm, in order to get the color effects on the sensor:

VIS vs. VIIRF (RGB with corrected WB) vs Reflective IR (RGB with corrected WB)

and another set of the same thing, only lit using a UV light source instead to see UVIIRF (uv induced ir fluorescence)

 

If the vis bulb you are using emits red around the 590nm range then it would be VIS mixed with VIIRF though, of course. could still potentially change the colors to something different/interesting and could potentially be applied to landscapes

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Thanks Pylon. I have seen sets of shots of various IR lonmgpass filters used for this, and in some cases I think using a lower longpass filter such as 700nm may reveal multiple wavelengths of fluorescence/luminescence.

For example, lets say we use a wide range of uv/visual light with a cut-off below the longpass filter. Keeping in mind that a longpass filter can transmit some visual light given long exposure time.

Various materials may be induced to fluoresce at different IR wavelengths and by different UV/Visual range wavelengths, thus producing a combined photo of multiple fluorescing wavelengths.

There may also be a question of if exposure time works to capture each material's fluorescence in the same shot.

I have currently be wondering about UV induced IR fluorescence (luminescence), but I have not found examples of this so far.

 

Several questions come to mind for any kind of fluorescence (luminescence):

1) inducing wavelength.

2) fluorescence wavelength.

3) materials expected to fluoresce.

4) expected fluorescence strength, or how much exposure time may be required to capture it (some materials may be induced to fluoresce, but may not be detected if exposure time is not long enough).

 

Here is an interesting pdf:

https://www.britishm...manual-2013.pdf

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If you know the pigments or chemicals involved in the fluorescence, then you can look up a lot of this information about excitation and emission wavelengths by Googling.

 

Example: Fluorescence of Carotenoids

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