Invisible Ink that you can see through an IR lens

[Aidentheawesome23]

TL;DR Summary

I need ink that reacts through an IR lens

I’m making an eyepiece that can see hidden messages, and I need to know an ink that you’ll be able to see through the IR lens.

 

[jedishrfu]

Some type of invisible inks in general:

https://en.wikipedia.org/wiki/Invisible_ink

and for IR in particular

https://www.sciencedirect.com/science/article/abs/pii/014372089400068D

You can also find more stuff via a Google search.

 

[Aidentheawesome23]

Some type of invisible inks in general:

https://en.wikipedia.org/wiki/Invisible_ink

and for IR in particular

https://www.sciencedirect.com/science/article/abs/pii/014372089400068D

You can also find more stuff via a Google search.

Just so you know, I mean looking through the actual lens, not through the camera

 

[Tom.G]

Why a lens instead of looking at it directly?

 

[chemisttree]

Your eye can’t see IR. Fools gambit. Lens doesn’t matter.

 

[jedishrfu]

Steganography rules!

 

[Aidentheawesome23]

I'm making a prototype of this, also what if there's light shining through the lens

 

[MidgetDwarf]

Theres a fountain pen ink made Noodler's. I forget the name of it, but just type in Noodlers Invinsible Fountain Pen Ink.

 

[HAYAO]

I'm making a prototype of this, also what if there's light shining through the lensView attachment 276950View attachment 276951

Is this from a game? Physically, the images already show a huge error in the concept.

The lens is red, which means the lens absorbs (or cut out) blue and green light, and only let's red light go through. So there is no chance that you can see a blue light (the second image) through the lens, unless they are upconverted (highly unlikely) or digitally modified.

You can't see IR light no matter what kind of lens you use. You need some sort of device that can detect IR light and digitally convert it into an image.

 

[DaveC426913]

You can't see IR light no matter what kind of lens you use.

Correction: Most people can't.

Generally, humans can see wavelengths down to about 750nm.

My son can reliably see the light from a TV remote - about 940nm - well into the near IR.
Yep. My son has a superpower.

So, the solution for the OP is ensure he is young of age.

 

[chemisttree]

Correction: Most people can't.

Generally, humans can see wavelengths down to about 750nm.

My son can reliably see the light from a TV remote - about 940nm - well into the near IR.
Yep. My son has a superpower.

So, the solution for the OP is ensure he is young of age.

I always thought that was due to the LED producing a distribution of frequencies?

 

[DaveC426913]

I always thought that was due to the LED producing a distribution of frequencies?

Perhaps, but that distribution is certainly entirely below my ability to detect.

 

[Drakkith]

Unless you have Dave's son's ability to see lower frequencies than the average person, you WILL need an IR sensor and a display device. A simple lens (or filter rather) won't do anything because it doesn't convert IR frequencies into visible light. You might as well use a trash bag as a filter otherwise (this type of plastic is transparent in part of the IR spectrum, but not the visible).

 

[AndrewW]

While it's not a direct answer to your question you might find this research interesting. By injecting special nanoparticles into the eye of rats it converted the IR light into visible blue light. If you wanted to incorporate this into an eyepiece then something like a pin hole camera with the nanoparticles embedded into the screen would work but the image could be quite dim. As for the ink, there are many pigments which are more interesting in IR than visible that's not too rare.