I think there have been several fictional works that directly addressed the issue that if a person were rendered invisible, they would be unable to see, because vision requires light to be focused by their eyes’ lens and absorbed by the retina. That interaction would make at least the eye itself visible.
The earliest example that I’m aware of is the 1968 novel The Goblin Tower by L. Sprague de Camp, in which a wizard, when asked to cast an invisibility spell, observes that
… to see in this condition, one must exempt one’s eyeballs from the spell.
I’m pretty sure I recall de Camp discussing this issue at greater length in another work, although I don’t recall which one. Do you know of any other works, either by de Camp or others, in which this issue is mentioned?
Fadeout, a superpowered crook in WILD CARDS, knew this, and would vary between ‘invisible, except for two eyes’ (which is still pretty danged stealthy) and ‘invisible but blind’.
I think there could be an ultra-high-tech solution to this; if the invisible man were wearing a cloak covered in tiny cameras which could record the surrounding scenery, then emit a detailed picture using tiny coloured LEDs on the opposite side of the cloak, you could have a kind of invisibility that allows you to monitor the local environment in detail without having visible eyes.
Given sufficiently advanced biotechnology you might even be able to build such a system into your skin. As a bonus it gives you 360 degree vision at the same time.
Hey, I only have one good eye… so I could be invisible except for ONE eyeball floating down the street (not at all attention-getting…).
Come to think of it, there are drawbacks to every super/magical power. So I’m going to stay “normal” (come to think of it, as I age I get more invisible… at least to millennial clerks and cliques of giggly teenagers).
Well, that is the idea. A cloak covered in a mesh of tiny cameras would look like a mesh of grey cloth; in between the cameras you have equally small LED emitters which project an image that hides the cameras.
If I’m understanding you, that wouldn’t work. I think you’re saying that the emitters would produce an image of what’s on the other side of the person. But it’s not possible to do that in a way that works for all viewing angles.
You are probably correct, but given the correct optics and enough information transfer between the different sides of the cloak, a pretty convincing image could be formed.
A perfectly convincing image could be formed, if there is exactly one viewer. But if there are multiple people viewing from different locations, it wouldn’t work at all for at least some of the viewers.
In the Recluce series, by L. E. Modesitt, the “order wizard” way of producing invisibility works by bending light around the wizard, and so they’re blinded. Order wizards generally rely on their magical senses while doing so, and with practice, can “see” using their magical senses nearly as well (or in some ways, better) than with their eyes.
Chaos mages can also produce an invisibility effect, but theirs works by hijacking the connection between the observer’s eyes and brain, and inserting a false image. So they don’t have that problem.
I think the Codex Alera, by Jim Butcher, addressed this, too (for air veils, at least: Wood veils are basically just really good camouflage), but I don’t recall the details.
This may not be the case. Here is a highly speculative article about optical phased arrays that might make it possible to make a relatively convincing image for all viewers. This sort of technology is probably many decades or centuries away, if it is possible at all.
I just quickly reread Jack London’s The Shadow and the Flash. Both approaches he addresses (perfectly black vs transparent) are portrayed as imperfect, but it doesn’t look like he considered this. He does air-brush one of the character’s eyeballs (!), but only to make them as invisible as everything else.
One thing you could do is also wear a device that lets you see in infrared or ultraviolet; if the invisibility effect doesn’t extend that far into the spectrum you could still see (and be seen) that way. And hiding yourself in infrared is extra-hard anyway, since after all we outright glow in infrared.