532 dot colour through goggles

[davidgdg]

I have a pair of Dragon orange/red goggles for working with my 532, 473 and 405 lasers.

When I view a 532 spot through the goggles, then depending on the reflecting surface, sometimes the spot appears green and sometimes yellow. It seems random. Thus:

Metalised aluminium ruler: green

Glossy dark navy paperback book: yellow

Semi-glossy dark navy hardback book: green

Pair of dark-navy woollen trousers: green (and now a small hole ;-(

Grey woollen "hoodie": yellow

Coffee mug: green

White paper surfaces: some green and some yellow

Antique mahogany desk: yellow

What's going on?

I was wondering if it was some kind of fluorescence, but it seems unlikely at 532nm and in any event, I can't see any pattern to it.

David

 

[Eudaimonium]

Green laser can get flourscent sometimes.
My green laser, when pointed at my red laser host, see here:
http://laserpointerforums.com/f50/powerfull-red-easy-simple-host-pics-high-res-included-44150.html
gives very rich orange, bright color.
Also when pointed at my multimeters probe, also does same thing. However, cable that goes to the probedoes nothing. Very ordinary green dot on it, but when pointed at the probes end (another piece of plastic, looks very much the same) giver strong orange glow.
Try finding red flourescent colored objects. After you get 'nuff of orange glow, get yourself a bluray, and enjoy glow of all colors.

 

[davidgdg]

Yes I think it must be slight fluorescence after all. Though it is odd that the green of the dot seems unchanged with the naked eye - just slight changes in brightness. Quite unlike the fluorescence that is produced by 405 which looks almost bluish to the naked eye.

Also, I wonder why the dot turns yellow under goggles. This suggests some longer-wavelength fluorescence which then combines with the residual green to produce a yellow effect. Again, very unlike 405 fluorescence.

I might do some experiments with my 473 to see what that does.

 

[pullbangdead]

A laser will fluoresce anything that fluoresces a longer wavelength than its own color. Violet can cause fluorescence in all other visible colors, because all other visible colors are longer wavelength than violet. Blue can fluoresce in green, yellow, orange, and red. Green can fluoresce in the yellow, orange, and red. Yellow can fluoresce orange and red, and so on.

You don't see the yellow normally because the green overpowers it, there's just too much green for your eye to see the yellow. But when you block the green, your eye can see the yellow quite nicely. But not every object fluoresces, only some things fluoresce. So, there's often not any other color of light being emitted.

But green light can't cause fluorescence in things that emit blue light, because the photon energy is too low. But blue fluorescent materials are very common around us, so when shining violet light at different objects, that's why you very often see blue fluorescence.

 

[Jaseth]

Apart from being a vital component in protecting your eyes, goggles really open up a whole world of fluorescence possibilities I love defocussing my blu-ray, putting on some 405nm goggles and shining it around, trying to discover different fluorescing items.
I guess I should also try it out with some greenies!

Seb

 

[Benm]

Its fluorescense alright. Normally this is hardly noticeable with 532 since the green is so overwhelmingly bright that a little higher wavelength emitted by the target is swamped out. The goggles block the green to a great degree, but will pass the fluoresence because of its larger wavelength resulting in some combination of colors, usually yellowish.

With 405 its a different story: if something fluoresces under that (say, plain paper) the fluorescence appears much brighter than the borderline invisible 405 even without goggles.

You might notice to some degree that the things that look yellow when irradiated by your green laser will mostly also fluoresce brighter under 405.

 

[davidgdg]

Its fluorescense alright. Normally this is hardly noticeable with 532 since the green is so overwhelmingly bright that a little higher wavelength emitted by the target is swamped out. The goggles block the green to a great degree, but will pass the fluoresence because of its larger wavelength resulting in some combination of colors, usually yellowish.

With 405 its a different story: if something fluoresces under that (say, plain paper) the fluorescence appears much brighter than the borderline invisible 405 even without goggles.

You might notice to some degree that the things that look yellow when irradiated by your green laser will mostly also fluoresce brighter under 405.

Thanks all. Fascinating stuff and the theory does indeed work. Just did a comparison of the (through-goggles) dot colour of 405 and 532:

*Anything that gives a big bright yellow dot (strong fluorescence) with the 405 gives a yellow dot with the 532 i.e. the yellow fluorescence caused by the 532 drowns out the green that is let through by the goggles.

* Anything that gives a small weak yellow dot with the 405 gives a green dot with the 532 i.e the fluorescence from the 532 is then too weak to drown out the green that is let through by the googles.