Digital Images In Ultraviolet Light

[Harry Pristis]

I just bought a new toy. It's a 51 LED ultraviolet flashlight.

A quick sweep of my fossils reveals that teeth from the Badlands flouresce nicely. With other fossils, it's hit and miss. Tampa Fm. agatized coral does flouresce.

Butvar-76 and Glyptal flouresce. Repairs with epoxy and epoxy casts flouresce brightly. Casts made of polyester resin do not flouresce. That is, in the wave-length produced by these LEDs.

Here is my first experiment in photography in UV light. Does anyone here have any experience at this? . . . any tips for making good images?

[

Edited April 24, 2012 by Harry Pristis

[Guest solius symbiosus]

I've never experimented with different wavelengths, but I have thought about it. It will be interesting to see other people's results.

[tracer]

I've never experimented with different wavelengths, but I have thought about it. It will be interesting to see other people's results.

short-wave is more expensive and dangerous but more minerals light up with it. a lot of field lamps now have both types of uv since some minerals will show with only one or the other.

[Guest solius symbiosus]

I have various narrow-band filters(though, they only permit certain visible specta); I might play around and see what shows.

[Harry Pristis]

I have various narrow-band filters(though, they only permit certain visible specta); I might play around and see what shows.

The wavelength of my LED device is 395 nm (nanometers), up at the high end of the UV spectrum.

I've discovered that shark teeth from Aurora flouresce nicely at this wavelength. To a lesser degree, so do teeth from the Moroccan phosphates.

Edited April 24, 2012 by Harry Pristis

[Harry Pristis]

The wavelength of my LED device is 395 nm (nanometers), up at the high end of the UV spectrum.

I've discovered that shark teeth from Aurora flouresce nicely at this wavelength. To a lesser degree, so do teeth from the Moroccan phosphates.

Here are some shark teeth from Aurora. It's difficult to capture the flourescence:

Edited April 24, 2012 by Harry Pristis

[Roz]

Harry

I once bought a hand held blacklight as I thought shark teeth

would show up at night using it. To be honest I am not sure

blacklight is the same as UV light. I tried it without success..

Love the images...

[Harry Pristis]

Harry

I once bought a hand held blacklight as I thought shark teeth

would show up at night using it. To be honest I am not sure

blacklight is the same as UV light. I tried it without success..

Love the images...

Glad you like the images, Roz. Shark teeth in the mine at Aurora might show up at night. You could hunt scorpions at night -- I understand that they flouresce nicely.

I'm having fun with this new toy. "Black light" and "UVA" are equivalent, pretty much, according to Wikipedia:

A black light, or Wood's light, is a lamp that emits long wave UV radiation and very little visible light. Commonly these are referred to as simply a "UV light". Fluorescent black lights are typically made in the same fashion as normal fluorescent lights except that only one phosphor is used and the normally clear glass envelope of the bulb may be replaced by a deep-bluish-purple glass called Wood's glass, a nickel-oxide–doped glass, which blocks almost all visible light above 400 nanometers. The color of such lamps is often referred to in the trade as "blacklight blue" or "BLB." This is to distinguish these lamps from "bug zapper" blacklight ("BL") lamps that don't have the blue Wood's glass. The phosphor typically used for a near 368 to 371 nanometer emission peak is either europium-doped strontium fluoroborate (SrB4O7F:Eu2+) or europium-doped strontium borate (SrB4O7:Eu2+) while the phosphor used to produce a peak around 350 to 353 nanometers is lead-doped barium silicate (BaSi2O5:Pb+). "Blacklight Blue" lamps peak at 365 nm.

While "black lights" do produce light in the UV range, their spectrum is confined to the longwave UVA region. Unlike UVB and UVC, which are responsible for the direct DNA damage that leads to skin cancer, black light is limited to lower energy, longer waves and does not cause sunburn. However, UVA is capable of causing damage to collagen fibers and destroying vitamin A in skin.

The UVA produced by the light-emitting diodes in my flashlight is at a frequency of 395 nm. This is the new technology that doesn't use a tiny flourescent blue-glass tube. Instead, it uses 51 LEDs that look like . . . well . . . like most other LEDs in a flashlight.

[Roz]

Hey thanks for the information..

I think Texas is loaded with scorpions but haven't seen one inside,

but will get my light out if I do..

[Harry Pristis]

I'm still experimenting with my UVA photography

-- can I be the only one?

One Carcharocles chubutensis (on the right)

flouresces brightly, while the other

does not flouresce at all!!

[

It's a mystery, this glow

-- sort of other-worldly for starters, but

how can this one tooth be blessed

with a halo and not the other?

I pondered the anomaly,

and as I did so,

I turned the flourescing tooth over.

There, plain as day,

on the labial side

for the world to see

was a possible answer . . . . . . . . . . . . .

Edited April 24, 2012 by Harry Pristis

[Guest solius symbiosus]

^^Yes, it seems as if the FSM, blessed be his name, loves to play tricks on us.

[Harry Pristis]

^^Yes, it seems as if the FSM, blessed be his name, loves to play tricks on us.

May you be touched by his shimmering noodly appendage!

[Harry Pristis]

As I mentioned earlier, epoxy resin flouresces but polyester resin does not. Here is a cast of a bear-dog maxilla made of epoxy resin colored with tempera pigments.

This is one of the first molds I made, so don't be too critical of the rendition. But, look at the way the epoxy flouresces in UVA!

Edited April 24, 2012 by Harry Pristis

[Roz]

Nothing wrong with that mold, looks like the one on the left.

Hey, your new toy would be a very good tool to examine fossils

before a person buys them to make sure they are genuine.

[Harry Pristis]

Nothing wrong with that mold, looks like the one on the left.

Hey, your new toy would be a very good tool to examine fossils

before a person buys them to make sure they are genuine.

They are the same cast, Roz, just photographed using different light.

Examination for authenticity is one of the prime uses for UVA (not to mention checking hand-stamps at your local concert or rave.)

I was surprised to find that polyester resin does not flouresce, though epoxy resin does. Among bottle collectors, for example, I would expect optically-clear polyester resin would be the repair material of choice, making UVA examination useless.

Body fillers like "Bondo" use polyester resin as a binder, so these would not flouresce.

But another dilemma has arisen. Epoxy repairs are very common in vertebrate fossil preparation. Vertebrate bones are often found in pieces, so patches, extensions, and joins are common. Perfection is appreciated in a vertebrate fossil; but, repairs are the norm, so such restoration does not much affect collector interest. (This is a somewhat different attitude than when dealing with invertebrates.)

The dilemma? . . . Some of my best, most esthetic vertebrate fossils look awful under UVA because of the lightning-streaks of expoxy joins and repairs!

Not the end of the world. Would I hesitate to use epoxy and hardwood powder as a filler in future repairs? . . . No!

It is one of those rare situations where knowing more about it can diminish appreciation of a fossil.