The Naked Scientists

The Naked Scientists Forum

Author Topic: DYE THAT CAN BE SEEN WITH A PAIR OF SUNGLASSES???  (Read 12747 times)

Offline Criddle12

  • First timers
  • *
  • Posts: 3
    • View Profile
Hey People,

I'm new to the forum and was wondering if there is a type of dye (preferably in the form of a marker or pen) that can only be seen with a pair of sunglasses? or special glass? I dont need a type of dye that requires a light I need it so I will be the only person who will see this dye. Please feel free to input any of your ideas.


 

Offline Ylide

  • Moderator
  • Hero Member
  • *****
  • Posts: 905
    • View Profile
    • http://clem.mscd.edu/~mogavero
Re: DYE THAT CAN BE SEEN WITH A PAIR OF SUNGLASSES???
« Reply #1 on: 09/04/2005 21:59:36 »
I've heard tales of someone using something like this to mark cards at casinos but I don't know what they could have been using.  There aren't glasses that can make you see in the infrared or UV spectrum except for like big bulky night vision goggles and inks are either going to reflect visible light or they're going to fluoresce under UV light which everyone would be able to see.

This message brought to you by The Council of People Who Are Sick of Seeing More People
 

Offline Ultima

  • Sr. Member
  • ****
  • Posts: 488
    • View Profile
    • My Homepage
Re: DYE THAT CAN BE SEEN WITH A PAIR OF SUNGLASSES???
« Reply #2 on: 09/04/2005 23:34:40 »
What about something that polarizes light and would show up using polaroid glasses?

wOw the world spins?
« Last Edit: 09/04/2005 23:37:49 by Ultima »
 

Offline daveshorts

  • Moderator
  • Neilep Level Member
  • *****
  • Posts: 2583
  • Physics, Experiments
    • View Profile
    • http://www.chaosscience.org.uk
Re: DYE THAT CAN BE SEEN WITH A PAIR OF SUNGLASSES???
« Reply #3 on: 09/04/2005 23:44:47 »
If you could control what you were writing on, you may be able to produce two yellows say that look the same to the eye but have different spectra, eg one just reflects yellow light, and another reflects green light and red light. If you looked at them with a red filter they would look different.

The disadvantage is that they would also look different under different lighting.
 

Offline Criddle12

  • First timers
  • *
  • Posts: 3
    • View Profile
Re: DYE THAT CAN BE SEEN WITH A PAIR OF SUNGLASSES???
« Reply #4 on: 11/04/2005 00:41:32 »
Thanks for the help guys. I was interested in what you had to say "Davidshorts." What you're getting at is a pair of colored filmwich is I dentifal to a colored layer which will cancel out that color. SO I should draw a on the serface with a extremely light color which is hardly noticiple to the eye . but because my glasses cancel out the first layer color, I can se the second color
 

Offline daveshorts

  • Moderator
  • Neilep Level Member
  • *****
  • Posts: 2583
  • Physics, Experiments
    • View Profile
    • http://www.chaosscience.org.uk
Re: DYE THAT CAN BE SEEN WITH A PAIR OF SUNGLASSES???
« Reply #5 on: 11/04/2005 03:24:43 »
Yeah that is some of it,

Basically primary colours are not due to physics at all, they are all to do with your eyes.

Light is a spectrum, there are an infinite number of pure colours (all the colours in a rainbow are pure colours) because there are an infinite number of wavelengths of light, however to deal with an infinite number of colours properly would produce far too much information for your brain to handle, so it simplifys things. You brain gets three numbers to describe the colour, the amount of reddish colours, the amount of greenish colours, and the amount of blueish colours.

 This means that you can produce the same effect in your brain by shining yellow light on your eyes as shining some red and some green light. If you then have some glass which only lets through green light the pure yellow will look dark, but because the mixture includes some green light it will look brighter.


This is why things look really odd under streetlights they produce a really pure yellow light rather than the mixture of colours a normal bulb or the sun produce. This means that you don't see any colour as things are only bright yellow or dim yellow.

 

Offline diegocuadros

  • First timers
  • *
  • Posts: 1
    • View Profile
Re: DYE THAT CAN BE SEEN WITH A PAIR OF SUNGLASSES???
« Reply #6 on: 11/11/2006 19:21:52 »
hey there..

have u found the invisible DYE THAT CAN BE SEEN WITH A PAIR OF SUNGLASSES????

if u have......please write back to diegocuadros@hotmail.com
 

Offline eric l

  • Hero Member
  • *****
  • Posts: 514
    • View Profile
Re: DYE THAT CAN BE SEEN WITH A PAIR OF SUNGLASSES???
« Reply #7 on: 12/11/2006 09:47:15 »
It is a bit more complicated :  you can have two dyes that look exactly the same under ONE kind of artificial light, but may look different under daylight, direct sunlight or even an other type of artificial light.
Leaving out fluorescence, a dyed object can only reflect wavelengths that are present in the incoming light (direct sunlight, daylight or artificial light).  The spectrum of e.g. diffuse daylight varies constantly over the day, the brain makes constant corrections for interpreting the signals received from the three types of cones to see white object as white regardless of changing light conditions.
So if you come up with a dye that you can only see (against a specific background) with your sunglasses UNDER CERTAIN CONDITIONS OF INCOMING LIGHT, it is quite possible that under other light everyone will see it, with or without sunglasses.
 

Offline Mjhavok

  • Sr. Member
  • ****
  • Posts: 468
    • View Profile
    • http://cantmakeadifference.blogspot.com
Re: DYE THAT CAN BE SEEN WITH A PAIR OF SUNGLASSES???
« Reply #8 on: 13/11/2006 14:50:23 »
Interesting question, why do you ask?
 

ROBERT

  • Guest
Re: DYE THAT CAN BE SEEN WITH A PAIR OF SUNGLASSES???
« Reply #9 on: 13/11/2006 15:50:39 »
there are an infinite number of pure colours (all the colours in a rainbow are pure colours) because there are an infinite number of wavelengths of light

I'm nitpicking, but I believe that there is not an infinite number of colours.
The states of the matter which produce the photons are quantized, so there will be a very large, but finite, number of wavelengths (colours) which can be created.
« Last Edit: 13/11/2006 15:52:49 by ROBERT »
 

Offline eric l

  • Hero Member
  • *****
  • Posts: 514
    • View Profile
Re: DYE THAT CAN BE SEEN WITH A PAIR OF SUNGLASSES???
« Reply #10 on: 13/11/2006 17:35:34 »
As I stated before, it is a little more complicated.  You can study colour from 3 different points of view, or in 3 different fields of natural science :
  • physical chemistry
  • physics
  • physiology
Physical chemistry describes how light is created or absorbed by making electrons shift from one orbit to another.  Because the energy involved comes in quanta, you have spectral lines and indeed not in infinite number of possible colours.
Physics describes the behavior of light, including things like the Doppler-effect, which changes the frequencies and so broadens the spectral lines to spectral bands.
Physiology describes how the human eye detects the light by means of rods (detecting total luminance) and cones (detecting colours).  Actualy, there are 3 types of cones, each with a sensistivity spectrum, corresponding more or less with the 3 colours in a colour TV tube.  I refer to wikipedia for details
http://en.wikipedia.org/wiki/Colour_vision
Now daylight has a practically continuous spectrum (rather than a multitude of lines), but the spectral curve (showing the energy for each wavelength) constantly changes during the day.  Artificial light on the other hand always shows bands. 
Photographers use "colour temperatures" to indicate the kind of light.  This colour temperature gives the temperature of a tungsten element that produces the same spectrum.  It is a bit odd that a higher colour temperature means a more blueish light, which would be felt as colder than a reddish light.

So keep in mind that the colour we observe is rarely the result of a single wavelength !
 

Offline daveshorts

  • Moderator
  • Neilep Level Member
  • *****
  • Posts: 2583
  • Physics, Experiments
    • View Profile
    • http://www.chaosscience.org.uk
Re: DYE THAT CAN BE SEEN WITH A PAIR OF SUNGLASSES???
« Reply #11 on: 14/11/2006 02:14:35 »

I'm nitpicking, but I believe that there is not an infinite number of colours.
The states of the matter which produce the photons are quantized, so there will be a very large, but finite, number of wavelengths (colours) which can be created.


Ok infinite is a big number but in free space light is not quantised. So unless the universe is finite in extent the number of allowable frequencies is not limited. Plus the wavelength can be altered by doppler shifts, so even if the light could have started off quantised (which is slightly debateable as the distance between the emmision lines in a solid are smaller than thermal pertebations) the wavelength can be red or blue shifted by tiny amounts. I'm not sure if that makes infinity, but I think it makes a much bigger number than you were thinking of ;)
 

Offline realmswalker

  • Sr. Member
  • ****
  • Posts: 205
    • View Profile
Re: DYE THAT CAN BE SEEN WITH A PAIR OF SUNGLASSES???
« Reply #12 on: 28/11/2006 02:51:49 »
you mean like this:
?
thats pretty cool, cheap to though
 

Offline eric l

  • Hero Member
  • *****
  • Posts: 514
    • View Profile
Re: DYE THAT CAN BE SEEN WITH A PAIR OF SUNGLASSES???
« Reply #13 on: 28/11/2006 09:30:46 »

I'm nitpicking, but I believe that there is not an infinite number of colours.
The states of the matter which produce the photons are quantized, so there will be a very large, but finite, number of wavelengths (colours) which can be created.


Ok infinite is a big number but in free space light is not quantised. So unless the universe is finite in extent the number of allowable frequencies is not limited. Plus the wavelength can be altered by doppler shifts, so even if the light could have started off quantised (which is slightly debateable as the distance between the emmision lines in a solid are smaller than thermal pertebations) the wavelength can be red or blue shifted by tiny amounts. I'm not sure if that makes infinity, but I think it makes a much bigger number than you were thinking of ;)

We should keep in mind that we can observe colours that are not part of the spectrum, because they are not related to one specific wavelength.  e.g. the blueish green that is used here for the links will show a number of peaks when you analyse it with a spectroscope.
But the eye does not work like a spectroscope, it works with three types of colour sensors called "cones" (in combination with one type of luminosity sensor :  the "rods").  These colour sensors have different sensitivity curves, that would show the response to 100 % luminosity for each wavelength. 
Any colour, wether it is monochromatic (=one wavelength) or not will give different responses in the three types of cones (colour sensors), which can be recorded as x, y and z.  There are instrument known as "colour analyzers" that can define a colour with these x, y and z values.
See also : 
http://en.wikipedia.org/wiki/Colour_vision (for colour perception)
http://en.wikipedia.org/wiki/Chromaticity_diagram (for measurement of colour along xyz-scales)

you mean like this:
?
thats pretty cool, cheap to though

What happens with the "invisible dye" and the sun glasses is that the sun glasses partially or completely remove a part of the spectrum.  In the picture I would say that the filter removes almost everyting but the red.  If your dye absorbs red more than other wavelengths, it may well be that you will not see any difference in daylight (without the sunglasses) because the input of energy from the other wavelengths is so high, but you see the difference when observing only a small part of the spectrum.  Anyway, when you watch the picture you can not say that the contrast with the sunglasses is very high.

Sorry if this posting turns out to be a bit long, it would have been much longer if I quoted the wikipedia stuff rather than just posting the link.
 

Offline Atomic-S

  • Hero Member
  • *****
  • Posts: 935
  • Thanked: 18 times
    • View Profile
Re: DYE THAT CAN BE SEEN WITH A PAIR OF SUNGLASSES???
« Reply #14 on: 03/12/2006 03:23:10 »
Presumably the dye is to be written onto white paper? That means that to the unaided eye, the dye must look white on white paper. That is more challenging than writing with one kind of yellow upon a yellow paper, because a white paper already reflects nearly 100% of all wavelengths, and what you can remove from that withkout it being conspicuous to the unaided eye is limited. I would think that any dye to do this must have a very narrow absorbtion spectrum, and the filter with which to view it must have a very narrow transmission spectrum. I am not aware of any commercially available marker that will do this.

I too have been faced with this problem and the closest I have come to a solution is to write with a canary-yellow pencil, which will become conspicuous if viewed through a good blue filter. This color is visible to the unaided eye; but because the central vision sees blue poorly, it has a hard time reading the yellow writing, especially in incandescent light.

The matter is further complicated by the fact that even if you write on white paper with a white pen, you may still be able to see the writing due to changes in the directionality of reflection of light, due to the gloss of the ink or due to the depression into the surface of the paper due to the pressure of writing.
 

The Naked Scientists Forum

Re: DYE THAT CAN BE SEEN WITH A PAIR OF SUNGLASSES???
« Reply #14 on: 03/12/2006 03:23:10 »

 

SMF 2.0.10 | SMF © 2015, Simple Machines
SMFAds for Free Forums