Green laser + Red Fabric Dye = Yellow-White Light?

Newbie to green lasers here. Just got a couple 5mw ones from China on an ebay deal for like $9 each. Then I drilled holes in the sides of them to access the pot to adjust them for 50+(?) mw without having to risk dismantling their pressure-fit components. (The lesser of the risk-evils.)

But aside all that ... I noticed a curious thing. When pointing these (now) higher-powered lasers at certain synthetic fabrics which contain a red-dye, the light coming back off of these fabrics is no longer a single-wavelength green. Instead the reflected/diffused light is now a bright yellowish-white color. This happens on the red ankle-band of a pair of sports-socks and also on the red fibers in a thick fleece throw-cover (blanket).

Does anyone know what specific dye that is used in these synthetic fabrics that causes this? And more importantly, can these green lasers be fed through a clear liquid of this dye and have it come out in this multi-spectral result? I've not looked at the resulting light through a diffraction grating (nor ritsy spectrometer) to be certain, but judging by the whiteness of the resulting light I'm certain that there are plenty of frequencies to play with after the green comes back out of this red dye. I'm not so much interested in plain fluorescence, but in a way that these lasers can be again converted into more frequencies, like in dye-lasers.

Any clues?

Re: Green laser + Red Fabric Dye = Yellow-White Li

I've noticed the same yellow reflection when shining on the pink Post-It notes in my office.

http://www.physics.ucla.edu/demoweb/outreach/Obamathon/color.html

Re: Green laser + Red Fabric Dye = Yellow-White Li

Very interesting.  I looked for pink Post-It notes but I don't have any, so instead I tested a bunch of marking pens on white paper.

One of them, a pink "Bic brite liner", looks yellow using my modified green pointer.  I also tested the pink plastic case for the pen, and it looks yellow as well.  The laser is 6.6 mW (using the Simple Laser Power Meter) but I haven't checked to see how much of that is IR (if any).

To see if this effect is from the 532 nm green, or the two IR wavelengths at 808 nm and 1064 nm, I shot the beam through a diffraction grating out to 10 feet so I got good separation of the wavelengths.  Then I checked only the green (I couldn't see the IR w/o more equipment).  The effect indeed is from the green wavelength.

To see the effect most clearly, I held the pink paper up to a white wall in a dark room and bounced the laser beam off the paper onto the wall.  The result is a diffuse green spot ringed in yellow.  

I dipped the pen point in water, but no color came off so I assume the ink isn't water soluble.

Below are some pics, with the later ones taken through a diffraction grating to show the different wavelengths.  From what I can tell, the pink plastic reflects green and generates red, and the combination looks yellow even though there isn't much if any yellow in the spectrum.

The last pic is of a pink dot made using the ink from the pen.  It looks like this spectrum actually does contain yellow.

Re: Green laser + Red Fabric Dye = Yellow-White Li

It is called fluorescence... (hence the term "Fluorescent Hi-lighter")
It's the same effect that you get when you play under a "black" light.

You won't see this effect with long wavelengths (red, near-infrared, infrared). Short wavelengths, green, blue, violet, and UV will do this with certain objects.

Check it out on wikipedia.

Edit: By the way, your green lasers are monochromatic, so the beam of your laser is not changing color. The yellow/orange is coming from the hi-lighter/post-it.

Wiki says:

Fluorescence is a luminescence that is mostly found as an optical phenomenon in cold bodies, in which the molecular absorption of a photon triggers the emission of a photon with a longer (less energetic) wavelength.

Click to expand...

Re: Green laser + Red Fabric Dye = Yellow-White Li

pierce said:

You won't see this effect with long wavelengths (red, near-infrared, infrared)...

Check it out on wikipedia.

Click to expand...

Thanks for the wiki pointer, that is helpful, although I couldn't find mention there of green being used for excitation.

I found this table listing some Fluorescent Dyes with their excitation and emission wavelengths.  
https://www.micro-shop.zeiss.com/us/us_en/spektral.php?f=fa&s=a&r

I see that the "Alexa 700" dye has an excitation wavelength of 696 nm, which is deep into the red.

Re: Green laser + Red Fabric Dye = Yellow-White Li

Also orange traffic cones relfect the green laser in the way described above. i found this out a few days ago.

Re: Green laser + Red Fabric Dye = Yellow-White Li

I remember when there was a dog toys upstair and i had my greenie, it flashed orange i was like ...

When i used to shine my bluray on the wooden floor it would turn white.
-Greg

Re: Green laser + Red Fabric Dye = Yellow-White Li

here's a vid of a green pointer and a red labby making a yellow dot on a white wall enjoy

http://www.youtube.com/watch?v=6d2G-9LmoFU

Re: Green laser + Red Fabric Dye = Yellow-White Li

If you shine the laser through a glass of the dye, the beam going through would be yellow, but a weaker green would come out. A laser is made up of completely coherent light, and you won't get anything from green but green (unless it's multi-line, but that's not DPSS...).

Re: Green laser + Red Fabric Dye = Yellow-White Li

Also tried it out

...using a fluorescent pen:



...using its ink:



It´s a nice little effect, isn´t it?

Re: Green laser + Red Fabric Dye = Yellow-White Li

AceGWC said:

...It´s a nice little effect, isn´t it?  

Click to expand...

Yes, though I'm not actually sure what I am seeing in the second pic?

BTW, what app did you use to combine the pics in the gif, if I may ask?

Thanks

Re: Green laser + Red Fabric Dye = Yellow-White Li

I´m using a trial version of the "Ulead GIF Animator".

In the second picture you can see the fluorescent marker´s ink having been soluted in a bottle of water resulting in a quite low-powered 5 mW greenie´s beam being clearly visible inside the water.

Re: Green laser + Red Fabric Dye = Yellow-White Li

Nice! Thanks!

Re: Green laser + Red Fabric Dye = Yellow-White Li

Thanks for posting these other interesting examples. It doesn't look like this dye can be used to change the laser's frequency I guess. Interesting, nonetheless, especially the diffraction-grating test to show what colors are making up that yellow-white color.

Whoever first pointed out fluorescence covered the query. A fun use for effect is looking through a red/orange filter while pointing the laser at or near fluorescing objects, it appears that they are brighter than the laser itself. In my experience, the light from most fluorescing objects appears as the dot form light simply reflected beside a continuous white spectrum that peaks around yellow (with my green laser on red objects at least), though I haven't done anything formal.

awesome necro
interesting thread tho.