Infra and Ultravision

[peter eldergill]

Are there are any creatures on earth that can detect infrared or ultraviolet with their eyes? I know that some creatures live entirely in the dark in caves/ deep ocean and so forth

Also, if our eyes could detect infrared, what would it "look" like to us? A different colour?

This is what happens if you stay in bed too long on a Saturday morning thinking too much :)

Pete

[grant hutchison]

Both parts of the spectrum are used for vision by various creatures. Apart from mugaliens, I don't know of any mammals with significant infrared vision, and I haven't heard of any creatures that use the same eyes for infrared as they do for the visual range (I'm claiming ignorance, here, not knowledge of absence). Pit vipers and other snakes use accessory infrared "eyes" as heat detectors with which they track mammals.
Many birds have UV receptors in their retinas, and bees can detect UV-reflective patterns on flowers. Humans can see some way into the UV if they have their eye lenses removed. (Modern lens implants filter out the UV to prevent retinal damage.)

The atmosphere scatters short wavelengths very strongly, so the world is a hazy place in UV, with lots UV-coloured air intervening between your eyes and distant objects. In contrast, IR is poorly scattered, so shadows are very dark under infrared illumination.
If you're limited to a single octave of light by the design of your eyes, and you want to be able to see clearly all the way to the horizon and into shadows, then what we experience as the "visible range" is a pretty useful one.

Grant Hutchison

Edit: As for what it would look like, I think that would depend on whether we had an extra receptor, or a receptor with an extended range. Under the former circumstance, we'd presumably experience four primary colours and a corresponding selection of secondary colours; under the latter, we'd have the same sort of colour vision, but the three primary colours would necessarily designate different mixtures of photons from those we detect now.

[Ara Pacis]

IR looks gray to me, but it has to be really bright in a pitch black room to see it. Of course, it may not have been IR I saw but something else that looked like a dull, dark disk of gray at the center of an IR LED.

[KaiYeves]

If you could see in x-ray, infared, or gamma and you looked at the sky, would you be able to distinguish any non-visible light objects with the naked eye? What about with a telescope?

[swansont]

Remember, the IR and UV wavelength cutoffs are somewhat arbitrary.

I've seen 780 nm and 852 nm light, and the 780 nm photons still looked red. Not surprising, as they were probably stimulating the red receptors in my eye. IIRC the 852 didn't have a perceptible color, but I can't say for sure as I saw it only peripherally before averting my gaze and correcting the safety issue. A spot needs to be pretty darned bright to see it at that wavelength.

[tdvance]

Are there are any creatures on earth that can detect infrared or ultraviolet with their eyes? I know that some creatures live entirely in the dark in caves/ deep ocean and so forth

Also, if our eyes could detect infrared, what would it "look" like to us? A different colour?

This is what happens if you stay in bed too long on a Saturday morning thinking too much :)

Pete

Bees: ultraviolet.

Pit vipers--infrared, at low resolution, but not with their eyes.

Note--people with their lens removed from their eye for various medical reasons, can see into the ultraviolet range. I think it just looks like deep violet. The cones are sensitive to ultraviolet, but the lens is not transparent to it.

[tdvance]

If you could see in x-ray, infared, or gamma and you looked at the sky, would you be able to distinguish any non-visible light objects with the naked eye? What about with a telescope?

Perhaps if you were above the atmosphere. The atmosphere blocks out all but what we call visible light +/- a little into the ultraviolet/infrared, and some radio frequencies. That's probably why our visual range is what it is--radio vision requiring macroscopic pixels being impractical for high-resolution vision.

(e.g. a radio telescope only takes one pixel at a time--it has to take lots of images to make a radio picture).

[tdvance]

Now, if we could see polarized light (see Heidinger's Brush on Wikipedia--it can be barely detected by some) the daytime sky would look different--we could then see the direction to the sun even if the sun were hidden. People who could see Heidinger's Brush, I remember reading somewhere, were once used to help ships navigate on cloudy days.

[SkepticJ]

Both parts of the spectrum are used for vision by various creatures. Apart from mugaliens, I don't know of any mammals with significant infrared vision...

Vampire bats have heat sensors in their noses. They detect long-wavelength infrared.

What mugaliens sees is near infrared -- just a bit redder than the reds that normal people see. I wonder if he/she can see the light from the diodes in a TV remote.

[grant hutchison]

What mugaliens sees is near infrared -- just a bit redder than the reds that normal people see.Yes, as swansont describes, the edges of the visual range are vague and some people have better sensitivity at the extremes than others. The sensation is usual a faint red, since it's the red receptor doing the work. That's "regular" infrared vision, in a way, and it's likely some other mammals can do the same thing. Ferrets, for instance, have reportedly been able to detect the IR illumination from night cameras, though it's difficult to be sure.

Mugaliens seems to be describing something rather different here, though:
As for IR, a warm iron with the kitchen lights on looks like... an iron. Same thing for a fire in a fireplace - it looks like a fire. In fact, with any incident light in the visible spectrum, including from a hot source, I see the same as anyone else. With all the lights off, however, after my eyes have had time to adjust (about 20 minutes), some things appear to have a faint glow. I can't call it color, as there's nothing to describe it (except perhaps "dark, ghostly").Grant Hutchison

[Torsten]

I had an unusual experience with extremely dim light on November 15, 2006. My snowmobile broke down about 13 km from my pickup at about 4:15 pm. By quirk of geography, my portable radio was unable to reach any repeater on the various networks around there, so I couldn't call for someone to help me. So I began the walk back to the truck, following the tracks I had made earlier in the day. I had left my headlamp in the pickup. The sky was overcast and the ~second quarter moon wouldn't rise until after midnight. The nearest community was ~65 km away, and the nearest other lights were at a lone house about 20 km away. Within an hour it was black.

Another hour into the darkness I realized I could still make out the silhouettes of trees alongside the road, and I could detect the outline of the track the snowmobile had made in the snow. I noticed that I could also just barely detect the marks made by the track's grousers. Amazed by this, I leaned closer to see if I could see more detail. They vanished! I don't think this is due to the difference between the density of rods and cones in the peripheral versus central fields of vision, because even while standing upright I was looking directly at the track. The best explanation I have is that as I moved in closer my body itself must have been blocking the critical few photons that were being reflected off the clouds from the nearest lights and allowing me to see anything.

Back to the OP though, I don't think this supports in any way the notion of IR detection. I just had plenty of time to adjust thoroughly to the low light conditions, and seem to have stumbled into a situation where I could sense myself pass through the threshold of light detection.

[Ara Pacis]

I wonder if he/she can see the light from the diodes in a TV remote.

I can, but only faintly and I have to hold it close. All I see is a dim disk of non-pitch-blackness.

[mugaliens]

I can, but only faintly and I have to hold it close. All I see is a dim disk of non-pitch-blackness.

Well, let's see...

Yep, but fairly visible. I see it as a light to medium gray. Unfortunately, as I held it about a quarter of an inch for my eye for about 1 sec of illumination, my eye now feels like I looked at something rather hot.

:doh:

I had to use my JVC DVD player remote, as my Sony remote has a visible red LED on top to indicate use, which interferred with anything I might discern from the signal LED.

Update - my eye feels better. It's probably fairly hot, as much energy as one would get from a keychain LED.

[Ara Pacis]

Yeah, my eye hurt afterwards too. I don't know if it was from concentrating too hard or from the photons.

But what I was wondering was if it was just IR being emitted or if there was some visible light being emitted too. I think there's a range of frequencies emitted by most LEDs other than LED lasers.

[mugaliens]

Yeah, my eye hurt afterwards too. I don't know if it was from concentrating too hard or from the photons.

But what I was wondering was if it was just IR being emitted or if there was some visible light being emitted too. I think there's a range of frequencies emitted by most LEDs other than LED lasers.

There is, but the range is fairly narrow (http://en.wikipedia.org/wiki/File:Red-YellowGreen-Blue_LED_spectra.png), with the runoff being extremely steep and almost linear. When you're 20% away from the modal frequency, the energy is practically undetectable.

[Ara Pacis]

There is, but the range is fairly narrow (http://en.wikipedia.org/wiki/File:Red-YellowGreen-Blue_LED_spectra.png), with the runoff being extremely steep and almost linear. When you're 20% away from the modal frequency, the energy is practically undetectable.

But we're talking about IR LED not red LEDs, but I wonder if a dim enough red would register as red or as gray. I suppose it depends on if it was stimulating a rod or an longwave cone cell. Or maybe it's genetic variation in pigments or tetrachromacy.

[Nick Theodorakis]

IR will heat things up, and, although I'm sure those remote controllers are low enough power to be safe in normal use, they probably didn't count on people holding the controller against their eye for long periods. So stop it.

Nick

[Ara Pacis]

IR will heat things up, and, although I'm sure those remote controllers are low enough power to be safe in normal use, they probably didn't count on people holding the controller against their eye for long periods. So stop it.

Nick

Near IR is not thermal IR.

[peter eldergill]

Either way, I'd appreciate it if no one hurt their eyes while looking into a question I posed out of idle curiosity! :)

Pete

[Ara Pacis]

Either way, I'd appreciate it if no one hurt their eyes while looking into a question I posed out of idle curiosity! :)

Pete

Unless you posted this question ten years ago and I forgot about it, there's no causality, at least as far as I am concerned. :)

[swansont]

Near IR is not thermal IR.

Doesn't matter — photon energy is photon energy. If it's absorbed, it will heat things up. The question is the power and duration.

"Thermal IR" refers to the emission spectrum, which peaks around 9 or 10 microns for things around room temperature. But any wavelength is capable of transferring energy — microwave ovens being an obvious example of this phenomenon.

[Nick Theodorakis]

Near IR lasers are definitely considered an eye hazard; of course laser intensity is much greater than most consumer LEDs.

In searching around, it appears that near IR has the same effect as any visible light sourse (except that blue wavelengths are more hazardous than shorter ones): intense exposure can cause retinal damage (far IR gets absorbed by the cornea). Whereas people have reflexes and behaviors that limit exposure to visible light (people turn away or avert their eyes from intense visible light), near IR does not elicit the same response, so it is possible to get a damaging exposure without knowing it.

I found this paper that examines some of these issues:

ICNIRP STATEMENT ON LIGHT-EMITTING DIODES (LEDs) AND LASER DIODES: IMPLICATIONS FOR HAZARD ASSESSMENT. International Commission on Non-Ionizing Radiation Protection. Health Physics. 78(6):744-752, June 2000.

[Ovid link (http://ovidsp.tx.ovid.com/spb/ovidweb.cgi?QS2=434f4e1a73d37e8ceddfcafb50d60f1111 beab897ae921f44867fe7b96a222d59dd468e37fbbf52d3fd2 249d4cdf63f947aa4cf87758e8cc35784c03eabbe70a09244d 16803da0ad1fc769a82aa72c4b684fa3b00292f68ce67c8176 10eca839d543e13a4e4b671b857934c2d4b9d3cf3483037a7f c3472d8d49e0e9dab88e915f1aef1f70c9905b58d94df57738 f947015c21d7f9372ac45dcd2536503b2cd556caaaab3e9fb6 f68c96ab110a6534e0605a8387d59f30b114bce96b2a6ba6a5 1dfec657a0fade51c51887dc796968fdc7d6db839347577591 37b5b8c33f1103027ae9aadacb823943f22a05968fb4a7#TT1 ).]

[Edited to add: I think you will need to be at an OVID-subscribing institution to view the link]

Although their conclusions are that IREDs are safe, they do give a number of quantitative assessments on likely exposures and possible dangers that may be of interest.

In regard to the post that brought this up, I thought this paragraph would be illuminating (pun fully intended):



Most IREDs are not visible under normal usage conditions. Although the CIE definition of the visible spectrum extends only to 780 nm, the visual response continues at very poor sensitivity to longer wavelengths. Therefore, high-radiance sources emitting wavelengths longer than 780 nm may be weakly visible (Sliney et al. 1976). Although most IREDs emit almost all of their energy within the wavelength range from about 800 to 980 nm in the near-infrared spectral region, many IREDs are just barely visible to most individuals viewing them in the dark


Nick

[mugaliens]

Well, there you have it. Thanks, Nick.

And to answer your comment (http://www.bautforum.com/general-science/83393-infra-ultravision.html#post1409569), Ara, the IR led it appeared as gray, not red.

[tdvance]

Well, there you have it. Thanks, Nick.

And to answer your comment (http://www.bautforum.com/general-science/83393-infra-ultravision.html#post1409569), Ara, the IR led it appeared as gray, not red.

I'd call it "dim white"--but that means it stimulated rods instead of cones. Cone stimulation I'm sure would be perceived as red--that it would stimulate the red far more than the other cones.

I think I know what you mean from a different experience--my parents' house has a woodstove for heat. I've often relaxed in the easy chair basking in the warmth and the glow--invisible infrared glow most of the time. However, at times the stove has been heated quite a bit, if the room is completely dark, one can just detect a faint glow on the stovepipe. I don't know the frequency, but suspect those frequencies being detected are at the very low red--high infrared range. Temp? never measured but definitely hot enough to boil water, not hot enough to ignite paper (not that it wouldn't char it maybe, didn't test for that long). That puts it between (Fahrenheit) 212 and 842 (I looked it up, the novel title is off by quite a bit!!! But 451C is a very good approximation). The blackbody radiation peak is well below visible, but some of the "tail" of the distribution goes into the visible range.

[mugaliens]

The blackbody radiation peak is well below visible, but some of the "tail" of the distribution goes into the visible range.

Indeed! BR follows Wien's displacement law, which governs the freq/temp relationship.

[Joe87]

Deer are supposed to be able to see into the near UV, which is why it is advised not to wash your hunting clothes in soaps containing UV "brighteners," which will make them stand out in the near UV, and might give away the hunter's location. Deer only have two types of color receptors, neither of which is sensitive in the orange range, which is why hunting clothes are orange. We can spot orange a long way off in the woods, but the deer can't.

[mugaliens]

Deer are also very poor shape resolvers. Quite often I have "snuck" up on deer from downwind in the middle of open fields simply by taking a step then freezing and making no sound.

On more than one occasion I've gotton close enough to reach out and touch them, but on most occasions, getting within abou 20 feet is common.

[tdvance]

There are now two presidents who evaded the Tecumseh Curse.

[mugaliens]

There are now two presidents who evaded the Tecumseh Curse.

Harrison, Lincoln, Garfield, McKinley, Harding, Roosevelt, and Kennedy.

What's the connection with the OP, tdvance - were they colorblind, or something?

[tdvance]

what! I intended to post in Leave A Random Fact...must have been adjacent to this thread in the list.

[KaiYeves]

Don't forget Zachary Taylor, who died completely independent of the 20-year cycle.

[grant hutchison]

what! I intended to post in Leave A Random Fact...must have been adjacent to this thread in the list.:clap:
Now that's what I call leaving a random fact!
Posting them in the "Random Fact" thread is so-o-o predictable. :)

Grant Hutchison

[cjameshuff]

I'd call it "dim white"--but that means it stimulated rods instead of cones. Cone stimulation I'm sure would be perceived as red--that it would stimulate the red far more than the other cones.

I picked out a couple high intensity IR LEDs last night and hooked them up...one clear envelope, one blue-tinted. The clear one had an easily visible dim red glow, the blue one a barely perceptible one. I seem to recall reading that it's the rods that are IR sensitive, and that dark adapted eyes with good infrared filters can see in near-infrared from sunlight, everything appearing pale and monochrome.

LEDs are pretty monochromatic, but they do emit over a range of wavelengths, so what I was seeing was probably a bit of stray visible red, bright enough to overpower the near-IR. Also, my apartment was bright enough for me to pick the LED by plugging a wire into the right breadboard hole...I didn't think about trying a closet or my bathroom, which would have let my eyes adapt further. (It was late...I was in bed staring at the streaks of light on the ceiling when I remembered this. In other news, I really need better window shades...)

[vk3ukf]

I've got a couple of pairs of infra red sunglasses, yup sunglasses.

Not battery powered techo things, just special filters that knock out nearly all visible light bar a thin line in blue, so, during the day the sky is the correct colour, but all living plants are of course wonderful shades of red darkening to what I believe is further into IR which appears to me as a strange colour similar to purple, but different. I understand that our eyes do delve barely into IR, the idea of the filter glasses is to block the main part of the spectrum that our eyes are sensitive to and leaving IR and a tad of blue for contrast and reality. With these glasses on I can spot a camoflague gun emplacement in a forest, it stands out like a sore thumb, take them off and it vanishes into the forest again. I have to leave them on for a few minutes before my eyes adjust to the very small amount of light reaching my eyes. I have tried to take a digital phot through the glasses and it came out sort of OK, but the colours were nothing like I perceived with my own eyes.
They were developed by a guy that sold them on ebay, at first they were gelatin filters between moulded perspex, then he got special lenses made doing the same job, then he vanished. I consider myself very lucky to have passive IR vision.

[trinitree88]

In photographic technology, they use dyes to extend the range of silver halide films/papers, by adding the dye solution to the emulsion. The dyes capture photons that would otherwise not create a silver speck in an oxidation reduction reaction...particularly in infrared...and release free electrons to do so to an adhered-to silver halide grain. There might be a way to inject a human eye with a dye solution that enables the spectral range to change in an analogous manner, giving one either temporary or permanent sensitivity...a big advantage in military situations.
I'm pretty sure I'm not the first to think this, but with today's stem cell work, the ability to experiment with this may be at hand. :shifty: pete

[mugaliens]

In photographic technology, they use dyes to extend the range of silver halide films/papers, by adding the dye solution to the emulsion. The dyes capture photons that would otherwise not create a silver speck in an oxidation reduction reaction...particularly in infrared...and release free electrons to do so to an adhered-to silver halide grain. There might be a way to inject a human eye with a dye solution that enables the spectral range to change in an analogous manner, giving one either temporary or permanent sensitivity...a big advantage in military situations.

You're thinking along some great lines, trinitree88. In fact, mother nature's lines.

Our eyes already contain such dyes, in the cone cells of our eyes (http://en.wikipedia.org/wiki/File:Cones_SMJ2_E.svg). Those dyes are called "photopigments" and they do just what you suggested - they absorb certain wavelengths of light, then activate the cone cells in which they're located.

They're sensitive to blue (420-470 nm), green (505-580 nm), and red (530-625 nm). The ranges are the 50% sensitivity level and higher, of wavelength. There's a lot of overlap, but neurological vision system can tell the difference. For tetrachromats (some humans are tetrachromats) there's a fourth photopigment in the cones.


I'm pretty sure I'm not the first to think this, but with today's stem cell work, the ability to experiment with this may be at hand.

It may very well take stem cells to achieve this, if not virally-transmitted genetic modification (gene therapy).

I do not believe, however, that this will be of military value. For the guys on the ground, low-light amplification is what's really key, allowing us to operate under the cover of darkness. Of course, with the proliferation of NVGs (http://en.wikipedia.org/wiki/Night_vision_device), a few hundred dollars now allows the enemy to spot us at night, so that side of the equation is lost.

For use in military aviation, it's much more advantageous, as it allows us to fly in night as we would during the daytime. It's not a perfect solution, however, as the best resolution currently available is equivalent to 20/400 daytime vision. Advances in both resolution as well as the widespread adoption of color NVGs (they're available) would help.

The biggest advantage for NVGs would involve innovation along the lines of how the rods and cones of our eyes pre-process visual information. This would allow for both much greater dynamic range within a single visual field (NVGs stink at this) as well as the much improved ability to differentiate between shading transitions, essentially, distinguishing edges. And, yes, the ability to flip into UV or IR, even deep IR (thermal) would be nice in some situations.

If such modifications became available, with the introduction of color (hexachromatism?), an increase in visual acuity (20/4, anyone?), the ability to zoom in at will, and a much wider visual field (peripheral vision), would be stellar.

Oh, and keep the weight to just 4 ounces, please. Anything heavier is a strain after a while...

[cjameshuff]

For use in military aviation, it's much more advantageous, as it allows us to fly in night as we would during the daytime. It's not a perfect solution, however, as the best resolution currently available is equivalent to 20/400 daytime vision. Advances in both resolution as well as the widespread adoption of color NVGs (they're available) would help.

You can go much further with aircraft. Rather than simple light amplification, you could have multiple cameras with different filters to achieve higher dynamic range and protection from glare effects as well as imaging in different bands of the spectrum, and synthesize radar, lidar, images taken under strobe illumination or daylight, and high quality thermal IR into an augmented reality representation of the surroundings. You could even combine imagery from multiple aircraft. All far more valuable than a few more colors.

It *would* be of some military value, indirectly. Color codes could be made more distinct, false color images could carry more detail, broader spectrum imagery would have a direct and intuitive representation. These would have importance in civilian life, as well. Anyone who works with plants would clearly benefit, as would geologists and microbiologists. Even cooks would benefit from being able to more easily discern variations in color.

However, it would probably need to be done during infancy in order for it to be really functional, and the above advantages would only be practical if the vast majority of the population had it done...and those without it would certainly object.

[Amber Robot]

(e.g. a radio telescope only takes one pixel at a time--it has to take lots of images to make a radio picture).


That's no longer true. Radio telescopes are beginning to use detector arrays.

[mugaliens]

You can go much further with aircraft. Rather than simple light amplification, you could have multiple cameras with different filters to achieve higher dynamic range and protection from glare effects as well as imaging in different bands of the spectrum, and synthesize radar, lidar, images taken under strobe illumination or daylight, and high quality thermal IR into an augmented reality representation of the surroundings. You could even combine imagery from multiple aircraft. All far more valuable than a few more colors.

Well, you can, but it gets a bit too heavy to wear on the helmet! The act of flying an airplane low-level, however, is too exacting to be fiddling with dash-mounted displays.

[trinitree88]

You're thinking along some great lines, trinitree88. In fact, mother nature's lines.

Our eyes already contain such dyes, in the cone cells of our eyes (http://en.wikipedia.org/wiki/File:Cones_SMJ2_E.svg). Those dyes are called "photopigments" and they do just what you suggested - they absorb certain wavelengths of light, then activate the cone cells in which they're located.

They're sensitive to blue (420-470 nm), green (505-580 nm), and red (530-625 nm). The ranges are the 50% sensitivity level and higher, of wavelength. There's a lot of overlap, but neurological vision system can tell the difference. For tetrachromats (some humans are tetrachromats) there's a fourth photopigment in the cones.



It may very well take stem cells to achieve this, if not virally-transmitted genetic modification (gene therapy).

I do not believe, however, that this will be of military value. For the guys on the ground, low-light amplification is what's really key, allowing us to operate under the cover of darkness. Of course, with the proliferation of NVGs (http://en.wikipedia.org/wiki/Night_vision_device), a few hundred dollars now allows the enemy to spot us at night, so that side of the equation is lost.

For use in military aviation, it's much more advantageous, as it allows us to fly in night as we would during the daytime. It's not a perfect solution, however, as the best resolution currently available is equivalent to 20/400 daytime vision. Advances in both resolution as well as the widespread adoption of color NVGs (they're available) would help.

The biggest advantage for NVGs would involve innovation along the lines of how the rods and cones of our eyes pre-process visual information. This would allow for both much greater dynamic range within a single visual field (NVGs stink at this) as well as the much improved ability to differentiate between shading transitions, essentially, distinguishing edges. And, yes, the ability to flip into UV or IR, even deep IR (thermal) would be nice in some situations.

If such modifications became available, with the introduction of color (hexachromatism?), an increase in visual acuity (20/4, anyone?), the ability to zoom in at will, and a much wider visual field (peripheral vision), would be stellar.

Oh, and keep the weight to just 4 ounces, please. Anything heavier is a strain after a while...

Mugs. Actually I thought of the idea in 92 at an AAPT Meeting at Wellesley College (my first). One of the instructors at the school was seeking to develop novel meds to inject into the eye to improve MRI images. Since the eye's vitreous humor is largely water, she was working with phosporus-inclusive derivatives. I have some experience in photographic coatings technology, and began thinking of the spectral sensitization of the human retina. Of course few people are going to volunteer for that trip, but the use of stem cells to do preliminary work is intriguing. It'd be nice to have the visual acuity of an eagle over a larger spectral dynamic range. I happen to have different color sensitivity in my two eyes, and can pick out dead plants at the garden center out of thousands of cuttings at a glance...very distinct albedo to me...the customers don't see it at all.
This would not involve a device, but an injection or use of something like DMSO to increase transport through the eye.
I was unaware of the fourth color cone tetrachromats...neat. Thanks. pete

[cjameshuff]

Well, you can, but it gets a bit too heavy to wear on the helmet! The act of flying an airplane low-level, however, is too exacting to be fiddling with dash-mounted displays.

A helmet mounted display suitable for the system I describe can be made far lighter and less bulky than a direct-view image intensifier, and can display anything without adding mass or bulk to the headgear. Some of the first such systems were largely intended to enable nap-of-the-earth navigation at night.

The F-35 uses a helmet-mounted display and a panoramic cockpit display in a system essentially identical to what I described, it actually completely replaces the traditional HUD. There's also the Joint Helmet Mounted Cueing System being used in several different aircraft.

[mugaliens]

The F-35 uses a helmet-mounted display and a panoramic cockpit display in a system essentially identical to what I described, it actually completely replaces the traditional HUD. There's also the Joint Helmet Mounted Cueing System being used in several different aircraft.

Lightweight, not bulky (http://en.wikipedia.org/wiki/File:Integrated_Helmet_Display_Sight_System.jpg).. .

:eek:

Just kidding. Here's the real thing (http://en.wikipedia.org/wiki/File:Joint_Helmet_Mounted_Cueing_System.jpg).

So long as it's just the imaging system which is helmet mounted, that's ok. Putting the sensors up there, however, is a bit weighty.