I was thinking about making up a visor like Batman has in the Arkham series, where he "analyzes" a sample and then he can set a filter on his visor for particles of that compound.

Something like analyzing ambient light and the way that light refracts when passing through that certain compound would be a way for example (I'm not saying that this is a thing that's possible though). Is there any way we could tell a part of a room that has an open bottle of liquor vs a part where there are mothballs.

Additional info (ask about anything you think is relevant, I'll add it here):

  • Funding of the device is not an issue, assume infinite funds.
  • Size of the device is also not an issue, I'm asking about the possibility of it, not applicability. (So, doesn't have to be a visor.)
  • $\begingroup$ Related: Synesthesia. $\endgroup$ – Harry David Jan 29 '17 at 23:42
  • $\begingroup$ @HarryDavid Not really. My question is about actually seeing stuff that smell (with the help of technology) not the connection between smell and sight neurons. $\endgroup$ – John Hamilton Jan 30 '17 at 15:06
  • $\begingroup$ Well, maybe the technology could do just that: Relay/redirect information about scent into the sight cortex of a user's mind, in the form of electrical impulses, which are then converted into visual colour by the brain... it isn't all that far fetched either, with already existing wearable technology able to convert sound into images and images (outlines) into vibrations that are felt on a persons tongue. $\endgroup$ – Harry David Jan 31 '17 at 5:52
  • $\begingroup$ But that would mean we would just "see" stuff we could already smell. The question is about seeing the smells from afar, without actually smelling them. @HarryDavid $\endgroup$ – John Hamilton Jan 31 '17 at 6:12
  • $\begingroup$ This would be useful for prompting early evasive action when someone farts. Oh - maybe that is the whole intent? Carry on. $\endgroup$ – Willk Feb 1 '17 at 15:30

There are several issues. You are asking two questions. First is a field gas chromatograph/mass spec device to analyse air samples and determine what compounds are present. Easy enough, although these machines are not necessarily very portable or very fast, the tech certainly exists, especially if there are only a few things it looks for (NBC detectors for the military are an example if small, portable detectors that just look for a few things).

But being able to visually sweep a room and "see" odor is another problem. Odor is really just very small organic and inorganic compounds and molecules that have to have physical contact with olfactory receptors in order to generate a "smell". The range of compounds is far, far greater than the visual light spectrum humans can distinguish. So you can't map all the olfactory range on-to the visual spectrum. Put perhaps you could map select compounds on the fly (like the Batman sensor).

But how to detect the compounds at distance? We smell at a fixed point and use some basic analysis to determine a direction, mainly detecting increasing or decreasing concentration and cross-referencing based on air flow and what we can see that might produce that smell. You can't "see" a source of odor, you can only detect it at the point it contacts the nose and follow it based on intensity. So while Batman can "see" footprints or whatever as if the odor source glowed, in reality you would have a gieger counter-like variable intensity light haze that increased in brightness as you approached an odor source. A Geiger counter is detecting particle concentrations and mapping them to an audio spectrum (tick frequency shortens as concentration rises), "visual smell" would be a haze in your vision that only extends an inch or two in front of your eyes but grows in brightness as you near the targeted odor compound.

Your only other option would be to make the target compound fluoresce in some manner. You would need to be able to emit radiation that only interacted with the target molecule and caused it to emit EM radiation itself (doesn't have to be in the visual range, just some wavelength your equipment could detect and map to your visual spectrum). Kind of like a black light, the target molecule "glows" only when the search beam hits it and excites it. This would let you see things from far away. I don't think many odor compounds could actually do this, but you could handwave it. It's been a while since I've played a Batman Arkham game, but I think this was sort of how it worked.

To speak to some of the comments, the way I would envision visual mapping of an odor would be a peripheral haze or rising bar on the edge of vision. You select the odor compound to be tracked and set a "zero" based on the concentration you are detecting at the moment. This starts at, say, 25% intensity but could be based on a known lower limit of detectability for that specific compound (most analysers have an upper limit as well which would require diluting the compound in order to lower it back into range, but we can ignore this for now. If it drops in concentration the intensity reduces from 25% to wards 0%. Of course in the real world there is no way to know that 100% equals "right in front of the source of smell" like in a game, but presumably you could set the scale based on numerous real world examples so that 100% would encompass realistic levels of smell exposure or the scale could be logarithmic in order to handle an unknown upper range of compound concentration.

AS for emitting a EM beam that detects compounds or causes them to fluoresce, I can't actually think of many examples other than the known excitable compounds we already have. If I had to handwave a technobabble solution (which I have no idea has any basis in reality) I would have a brief intense IR heat pulse that creates a pseudo flame photometric effect that could be detected at range. Sort of an "odor radar" if you will. With a high enough sensitivity and resolution, you wouldn't need to ignite much in order to detect the compounds, so you wouldn't have to set everything on fire just to measure the spectra.

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    $\begingroup$ So, instead of the solution being a track of odors, you could see a bubble of odor area (or more precisely how concentrated the odor is and it would most likely be in a bubble area) and then, with enough data, you could tell a direction for the source. This is close enough to what I want but that last paragraph is exactly what I wanted. Produce EM waves, bounce them and get data back. Sounds plausible but I'd like to see sources that did this (or something close). I'll pick this as the answer if you can link some here. $\endgroup$ – John Hamilton Jan 28 '17 at 18:15
  • $\begingroup$ that's exactly how smell works now, Jason is just adding a computer to translate smell into a 3D representation, it is a Electronic nose attached to a mapping program. $\endgroup$ – John Jan 29 '17 at 14:13
  • $\begingroup$ I read that, while our vision is done in 3 dimensions, (red, green, and blue), our sense of smell is defined by 300 unique dimensions (different olfactory receptors that respond to different classes of chemicals) $\endgroup$ – Cort Ammon Jan 29 '17 at 16:06
  • $\begingroup$ So, this smell to vision type of visor would essentially need a server (like Batman has in his cave) and a data link with a screen and a special camera (the visor). All in all, I think this is the answer that's needed here. Thanks for the link by the way, it lead to some good reads. $\endgroup$ – John Hamilton Jan 30 '17 at 15:09

after finding these two pages, I have determined that you are describing existing technology.

Basically, chemical analysis is done by vaporizing a sample, shining a light through it, and analyzing the color of the light.

Once the chemical analysis is done, the odor can be identified.



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  • $\begingroup$ except they only work becasue the sample is isolated and lit by only one source. $\endgroup$ – John Jan 28 '17 at 17:43
  • $\begingroup$ I'm sure that, with unlimited funding and a reason to spend it, science could eventually fine-tune the sensors to compensate for different types and numbers of light sources. The current technology stopped where it is because there is no need for it to proceed to the level you're describing. $\endgroup$ – Brian Lami Jan 28 '17 at 17:59
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    $\begingroup$ you can compensate for it, you ignore the bulk of the data and use normal vision, to separate out confounding information you sample the material in a isolated environment, where you can calibrate for all the variables not coming from the sample material. your problem is a visor would not be able to tell the difference between green light coming through a red media from, a red light coming through a green media, from white light reflecting off a yellow media. Things like reflection and ambient light are going to wash out your spectral lines. $\endgroup$ – John Jan 28 '17 at 18:09
  • $\begingroup$ or you could use lower fidelity sensors to analyze the environment and calculate this into the higher fidelity sensor data to compensate. this would be possible with more highly advanced computer technology $\endgroup$ – Brian Lami Jan 28 '17 at 18:55
  • $\begingroup$ possible with an AI, and you still would get a very poor showing, many organic compounds will have the same spectral lines, while having distinct smells. $\endgroup$ – John Jan 29 '17 at 14:16

No becasue the spectrum of light coming into the room is uncontrolled and from multiple sources, and the light is passing through all the material between it and the source. You would just see a muddy mix of all the materials between the various light sources and the visor, Then you add it reflection and refraction. All that overlap washes out and spectral lines.Light is just a bad way to detect smell.

batman is just better off using a electronic nose and letting normal diffusion bring the sample to you. Or he can used targeted fluorescent antigen like sprays as Jason was mentioning, police already do this.

Here is a link about how smell works http://www-f1.ijs.si/~rudi/sola/Physicsofsmell.pdf

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