Seeing into the near IR with just our eyes?

[dabateman]

Looks like a study will come out soon, where mice were injected with a special type of nanoparticles called upconversion nanoparticles (UCNPs) into the eyes. Normal mice wete used. The nanoparticle solution contains the rare-earth elements erbium and ytterbium, which can convert low-energy infrared photons into higher-energy green light that is visible.

 

This looks interesting. The side effect was cloudy eyes for a week but the ability to see IR lasted 10 weeks. That is a long time for a mouse.

 

Updated link as off main page:

 

https://www.zmescience.com/science/scientists-create-supermice-that-can-see-infrared-light/

 

[Andy Perrin]

Hm. it says they did inject the fluid into the retina, so maybe they would see an image. It works just like those Edmund cameras with upconversion phosphor coated CMOS sensors for SWIR.

[dabateman]

I think this would hit the military first. A night time injection to get better than night scope vision. Also, could reserve those to just night shifts or patrols.

The mice were able to recognize stuff in just the Near IR. So I think you could fully see stuff.

[Cadmium]

Yeah, I don't know much about all of that...

I don't know how many of you sit around all day like I do (am am joking here) looking through IR longpass filters at some 1980's 75w incandescent light bulb... trying to discern any red passed to the eye from 780nm, 800nm, 830nm, 850nm, and even 1000nm filters...

I can't see anything through a 100nm filter, but indeed I can through 850nm. It is very very slight.

OK, I might be wrong about that it might be 830nm, but I think even 850nm.

Point being, the eye can see past 720nm, for sure.

Lets say we take an 830nm filter at 2mm, it has a "0" threshold of about 780nm, so the eye can see that high at least.

Of course, such extremely high IR would only be available in a situation that is absent of all other lower visual light, just as if you were to block all visual/IR light above 400nm, then you may be able to see some violet,

but be very careful testing that idea... UV is defiantly more dangerous to your eyes... and who know how dangerous IR is really when the eye is left wide open to it?

[eye4invisible]

What can also be considered, when making the comparison between the human eye and an IR-capable camera, would be the analogous reference to the lens.

 

For example, a family friend that had cataract surgery mentioned that colours seemed more vivid after the procedure (his words were along the lines of the colours that one sees in Technicolor films). So, does an acrylic intraocular lens implant pass more IR than the original lens?

[Bill De Jager]

For example, a family friend that had cataract surgery mentioned that colours seemed more vivid after the procedure (his words were along the lines of the colours that one sees in Technicolor films). So, does an acrylic intraocular lens implant pass more IR than the original lens?

 

I've had cataract surgery in one eye. Yes, colors are more vivid, but I think that's more a matter of the natural lens in the other eye very obviously providing a yellow/brown cast to what I see from that eye. The eye with the artificial lens is seeing nothing different from what I used to see when I was younger, other than the other optical defects (floaters, etc.) that are not due to the lens.

[Andy Perrin]

I don't know about now, but certainly in the past cataract patients have mentioned having some sensitivity to UV (probably in the 380-400 or even narrower). I have not heard about IR.

[eye4invisible]

I've had cataract surgery in one eye. Yes, colors are more vivid, but I think that's more a matter of the natural lens in the other eye very obviously providing a yellow/brown cast to what I see from that eye. The eye with the artificial lens is seeing nothing different from what I used to see when I was younger, other than the other optical defects (floaters, etc.) that are not due to the lens.

Interesting perspective. I guess it's different for everyone.

[ulf]

The sensitivity is tapering off gradually in both ends of the spectrum and the limits are varying from person to person.

If the light is strong enough it can be seen.

 

As an example the laser light from a CD-player can be seen as a faint red dot. The wavelength used is around 780nm

This is safe as long as the focussing lens is in place as the light is spread very widely (NA ≥ 0.45) and the focus point is a few millimeters from the lens.

Do not look into the collimated beam with the focussing lens removed!

 

When looking at a DVD players laser light, with an optical power in the same region, but with red light instead, it is obvious how much light both readout-systems use.

[dabateman]

Old DVD lasers were fun. CDs and lazer discs used 780nm, DVD-rom drives just had 650nm, but the DVD-R drives had a 635nm laser for writing. I think the DVD+R drives were similar, just used a different dye in the disc to allow the first dual layer writing.

 

Blu-rays are 405nm. Now with SD, microSD, I don't see a need for slow optical discs. So I don't think we will get a cheap UV laser due to common optical discs.

 

I think with all the dark UV photography I have been doing. My eyes have adjusted lower. I am fairly certain I can almost see to 380nm now. I can see just through a Baader filter.

 

Human vision range is rated from 380nm to 750nm. But no doubt there is variability among us all.

[ulf]

Old DVD lasers were fun. CDs and lazer discs used 780nm, DVD-rom drives just had 650nm, but the DVD-R drives had a 635nm laser for writing. I think the DVD+R drives were similar, just used a different dye in the disc to allow the first dual layer writing.

No, the DVD-R and DVD+R formats used similar dyes, even if the suppliers and brands could differ.

 

To get dual layer writing the first golden mirror layer was very thin with a reflectivity of ca 20-25%. The innermost reflector was made ticker to maximise reflectivity.

The laser spot was focussed on the layer of interest and as the focus depth was very thin the other layer was not affected.

The difference between DVD-R and DVD+R was mainly in tho the position information in the tracking groove was optically formated.

The technology became even more interesting with the DVD-RW formats and Blu-Ray discs.

[Andrea B.]

I have the two-different-eyes thing also.

I've written about it before, so feel free to skip!!

 

My left eye was treated for cataract (and a couple of other problems). The intra-ocular lens implants typically have a natural color curve which reproduces colours as seen by a younger person. Mine is like that. These days the IOCs block most UV below 380 nm**. Oddly, they called my IOC a "blue-blocker", but it does not block blue, per se. They just mean that there is a strong left shoulder on the natural colour curve. But it does permit passage of UV/violet from 380 nm (Only an estimate, I'm not sure of the exact curve).

 

When I look at blue sky with my good left eye, it is much bluer than when I look with my "bad" right eye which has the yellow lens effect due to the eye's aging (which we all get). The sky looks more of a cyan blue using the bad right eye. When I look at the sky with both eyes, one blue-sensitive and one with yellowed lens, the brain takes over and says the sky is blue just as it always has been. So don't worry if you have aging eyes and think you might not be seeing a true blue sky.

 

Colours are more vivid after cataract surgery because the cataract has been blocking light. My right eye is now noticeably blocking light, so I'm going to have to get it fixed soon. Immediately after cataract surgery the restored light causes the vividness to be quite noticeable. As the brain adjusts, colours begin to seem "normal" again.

 

Violet is a different story. I can only see true violet with my IOC left eye. I cannot see true violet much at all with my yellowed right eye. I tested this with a violet LED. Can't recall the peak, but I think 405 nm or 410 nm??

 

**UV-blocking IOCs or contact lenses cannot block UV from all angles. It is still important to wear wrap sunglasses. Or wrap UV-block goggles if playing with UV-flashes or UV-LEDs.