[HN Gopher] Laser-based device can scan almost any sample of gas...
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Laser-based device can scan almost any sample of gas and tell you
what's in it
Author : PaulHoule
Score : 104 points
Date : 2025-03-07 16:06 UTC (6 hours ago)
(HTM) web link (phys.org)
(TXT) w3m dump (phys.org)
| 01100011 wrote:
| Now can we use this to do smog checks on cars as they drive so I
| can avoid the biennial chore of taking the car in to a shop?
| idontwantthis wrote:
| Do they still actually analyze the gas? When I did mine they
| just plugged into the computer and it was done in 10 seconds.
| PaulHoule wrote:
| The point of
|
| https://en.wikipedia.org/wiki/On-board_diagnostics
|
| is that the engine control unit in your car is monitoring the
| operation of the engine and thinks it is in spec. If the
| computer says it is OK, it is OK, at least in most states.
|
| For years there has been talk about an OBD-III that would use
| the cellular network or something so your car can narc on you
| if it is out of spec
|
| https://www.hotrod.com/features/obd-iii-the-proposed-
| future-...
|
| This has been stuck in purgatory with all the other proposals
| for universal telematics not least because of privacy
| concerns plus cell phone carriers being uninterested in
| anything other than "what's convenient for us" coverage.
| ziddoap wrote:
| > _If the computer says it is OK, it is OK, at least in
| most states._
|
| The downside of this method (or upside, I guess, depending
| on where you stand), over the sniffer method, is that this
| is trivially bypassed. My race car, which is by no means
| emissions compliant, can pass this check with the press of
| a button.
| Aurornis wrote:
| States are beginning to roll out systems that do deeper
| checks on the firmware. Those, too, can be bypassed
| especially on older systems. However a lot of people are
| getting caught at emissions time now with cars that have
| been passing for years.
| PaulHoule wrote:
| Notably the functional test (measuring exhaust) can be
| gamed too, see
|
| https://en.wikipedia.org/wiki/Volkswagen_emissions_scanda
| l
|
| Emission control is a balance between emissions, fuel
| economy and performance. You can give up some fuel
| economy and or performance at test time and enjoy better
| performance at the rest of the time if the system knows
| it is being tested.
| PaulHoule wrote:
| I remember people from Sandia National Labs using LIDAR to
| monitor pollution around Albuquerque circa 1990. Turns out this
| been a thing for a long time:
|
| https://ntrs.nasa.gov/citations/19720026861
|
| and is still going on
|
| https://iopscience.iop.org/article/10.1088/1748-9326/ab9cfd
|
| https://idstch.com/security/lidar-technology-revolutionizing...
|
| I think in those cases you know what the pollutant is that is
| in a gas that you know what it is and want to make a
| quantitative determination whereas the system described in that
| paper is supposed to make sense of some random gas.
| aerostable_slug wrote:
| Sandia and other labs have indeed been working on this type
| of MASINT collection for a long while. Their primary use case
| is remote characterization of effluents to determine if a
| given facility is being clandestinely used for things like
| chemical weapons production or nuclear materials enrichment.
| datadrivenangel wrote:
| In Virginia they do this! They have devices that they'll put
| near highway on/offramps and rotate them between locations
| every few weeks or so.
| BobaFloutist wrote:
| No, I want to add headlight lumens/angle checks and window tint
| checks to the smog check. It's an annoying chore but it's the
| one time car owners have to (semi-regularly) get their car
| looked at, we should take advantage of that.
| dv_dt wrote:
| It would be great to sample plastic and get composition
| sufficient to determine a recycling category
| bluGill wrote:
| We already do that. However not all plastics and be determined
| that way. Black plastic in particular often cannot be figured
| out (since the laser as absorbed) and so even if the plastic is
| easy to recycle it is often land filled.
|
| There are open questions on if recycling plastic is worth
| bothering with at all, but that is a different debate.
| whatshisface wrote:
| If you zapped it you'd have vapor to analyze.
| aj7 wrote:
| One time at the laser show, the booth across from us had a
| methane analyzer.
|
| You could tell when people farted.
| throwup238 wrote:
| Simple hand held methane detectors have been around for a
| few decades.
|
| This was used to great effect in the Kenny VS Spenny
| episode, Who Can Blow the Biggest Fart:
| https://youtu.be/ash2NzL1IHo
|
| (It's a Canadian show)
| colechristensen wrote:
| I prefer the trash to electricity route.
|
| If you think about it, the oil just took a detour into being
| a water bottle or whatever for a little while on it's way to
| the power plant. I really can't imagine we'll be at 0
| hydrocarbon electricity grid any decade soon and burning
| garbage (and instead of "recycling" plastic) seems to be a
| perfectly reasonable thing to do if you can do it cleanly in
| a power plant.
| Animats wrote:
| > We already do that
|
| Here's the machinery doing it.[1] It's just using RGB and IR
| cameras; they're not using lasers to vaporize samples and
| analyze the spectrum. That would be both overkill and a fire
| hazard.
|
| Overview of modern waste handling.[2] Most of the separation
| is entirely mechanical, with screens, vibrators, rotating
| drums, and air blasts. But HDPE and PET plastics are
| separated using infrared sensing.
|
| [1] https://www.youtube.com/watch?v=51S3ET7M138
|
| [2] https://www.youtube.com/watch?v=6rkHt34AztY
| jfim wrote:
| Oooh, so that's why the local recycling facility doesn't take
| black plastics. Thanks for sharing!
| dv_dt wrote:
| Thats good to know. On recycling or not, i dont think it will
| ever be a universal yes or no. But if the tech was there to
| reliably identify & pull out a processable stream that has
| concrete assessable value. Its probsbly a harder requirement
| on some sensing tech to do it with continuously on an
| industrialized stream of refuse.
| TuringNYC wrote:
| >> It would be great to sample plastic and get composition
| sufficient to determine a recycling category
|
| i love this idea. i cant believe how tiny the marked recycling
| categories are on the containers, i can barely see them. i
| always wondered how they even achieve this at the town
| recycling center.
| colechristensen wrote:
| >how they even achieve this at the town recycling center
|
| They don't. A huge proportion is never recycled at all.
| klysm wrote:
| Plastic generally isn't recycled that much, and many kinds of
| plastic cannot sustainably be recycled.
|
| There's a lot of automation in the space, and none of it uses
| the markers
| ianburrell wrote:
| The marks on plastic aren't recycling categories, they
| identify the plastic resin. They partially indicate
| recyclability but the form is important. I don't think they
| are used at recycling centers which mostly go on common
| shapes. Products are supposed to now use solid triangle to
| reduce the confusion with recycling.
| klysm wrote:
| We do this already, but also for metals which have a much more
| reasonable recycling story. In metals though, we use LIBS.
| Tomra makes the best machines currently
| aantix wrote:
| If you wanted to identify the components of a liquid, could you
| heat it and analyze the steam?
| Keyframe wrote:
| if it can survive phase transition untouched. otherwise, if
| there'd be a chemical change, you'd be looking at something
| new.
| zdragnar wrote:
| I apparently have watched too much explosions & fire /
| extractions & ire, because my immediate thought on seeing the
| parent comment was that "yeah, it's gonna decompose before it
| vaporizes, and if it's hypergolic with itself that'll be fun"
|
| Apparently, watching an Aussie with a backyard shed full of
| mysterious chemicals and reagents has me assuming that any
| mysterious, unmarked liquid that needs to be identified is
| probably explosive.
| Keyframe wrote:
| well, given the right conditions and enough heat...
| rtkwe wrote:
| AFAIU most methods of spectroscopy work by measuring the
| atomic composition of the materials anyways not the exact
| structure and bonds so a chemical change shouldn't matter
| much.
| Keyframe wrote:
| that'd make sense
| kurthr wrote:
| Usually, they use HPLC (high pressure liquid chromatography),
| which uses a solvent and packed diffusion columns.
| WhyNotHugo wrote:
| Different components might vaporise at temperatures.
|
| If you heat water and alcohol to 80deg, measurements would
| indicate ~100% alcohol.
|
| You won't know the right temperature unless you know what
| substance it is.
|
| Edit: I guess you might also have stuff which reacts below
| their vaporising temperature.
| egberts1 wrote:
| Every phase transistion (or phase change) of a molecule alters
| its emission lines, at least as detected by gas chromatography
| equipments.
| aj7 wrote:
| You could taste it.
|
| But working on a good dog interface is the way to go.
| DecentShoes wrote:
| Man, the next Vessyl is going to be intense...
| xeonmc wrote:
| Similar concept to FTIR in terms of de-convolving a known
| agitation pattern to enable more robust signal collection.
| rz2k wrote:
| I wonder how the mirrors are cleaned or kept clean. Maybe that
| isn't an issue when detecting concentrations that would take a
| mile of light to measure, and existing NDIR detectors are
| sufficient for things like detecting different gasses in
| pollution.
|
| It would be nice if there were general purpose gas measurement
| sensors that could identify more gasses rather than being
| specialized to a specific gas. Could this be done by replacing
| the circuitry of a typical evaluation board with an interface to
| something like an NVidia Jetson Orin Nano?
| condensedcrab wrote:
| Usually cavity mirrors would be somewhat sealed to prevent
| dust/junk build up.
|
| Problem with general purpose spectroscopic measurements is that
| you need a broadband source and detector. This adds complexity
| compared to a targeted wavelength range.
| jmusall wrote:
| You usually mount mirrors vertically so dust does not settle on
| them that much (also it is safer to keep laser light
| propagating horizontally at only one height). Additionally,
| overhead ventilation is often installed which provides a
| vertical Laminar flow of dust-free air. If you have to clean
| the mirrors eventually, you'd use compressed (clean) air or
| special mirror cleaning wipes. Thorlabs (lab supply company)
| has a detailed guide on optics cleaning[1]
|
| [1]
| https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=90...
| aj7 wrote:
| People can't even tell how much cheap oil is in olive oil, let
| alone "extra virgin olive oil" vs. el cheapo olive oil. Take it
| from this old laser spectrocopist. When there's 75 mirror mounts
| on a 4 foot by 8 foot table, with a Chinese graduate student
| handcuffed to the table to adjust them, it's at least a decade
| away. When you can buy a frequency comb laser on Aliexpress, now
| we're talking.
| j45 wrote:
| Available on Aliexpress really is a solid indicator.
| kylehotchkiss wrote:
| Why did you handcuff a grad student to the table?
| generalizations wrote:
| Presumably they require constant high-precision adjustment
| and a lot of domain knowledge. I'd read it that the only way
| to do it now is with a high-maintenance setup and a lot of
| technicians.
| khazhoux wrote:
| Yea, buy why handcuffs? Is it to limit range of motion when
| taking precision measurements?
| nartho wrote:
| I believe this was a figure of speech to illustrate that
| the student has to stay right by the table, not that the
| student is actually being handcuffed
| analog31 wrote:
| It's like how Odysseus demanded to be tied to the mast of his
| ship, so he wouldn't be tempted by the Sirens.
|
| The grad student doesn't want to be tempted by the software
| industry offering to quintuple his salary.
|
| (Disclosure: Former physics grad student, who tended a
| similar optics bench).
| caycep wrote:
| forget software, they all go into starting boutique
| bakeries
| contingencies wrote:
| To stop them leaving academia for the private sector.
| Eduard wrote:
| searching for "frequency comb laser" on Aliexpress doesn't
| yield fitting results currently for me.
|
| https://de.aliexpress.com/w/wholesale-frequency-comb-laser.h...
| gregschlom wrote:
| yes, that's the point.
| ck2 wrote:
| Shame this won't work lightyears away
|
| very hard to detect oxygen around exoplanets apparently but they
| came up with a new method recently
|
| https://news.ucr.edu/articles/2020/01/06/scientists-develop-...
| zerealshadowban wrote:
| It seems that the frequency comb laser is easy to diy! "NIST
| Shows How to Make a Compact Frequency Comb in Minutes" (2013)
| [0]. I can think of many applications apart from the medical
| diagnosis they talk about.
|
| The varying mirror cavity is today's innovative step, plus the
| computation to identify atoms and molecules from the observation
| of color absorption.
|
| [0] https://www.nist.gov/news-events/news/2013/07/nist-shows-
| how...
| aj7 wrote:
| Yes. And a surgeon can remove your appendix in minutes too. A
| 777 can be landed in a crosswind, in minutes. Why a pass can be
| intercepted and run back for a touchdown in seconds! All of
| this easy. I've seen it on TV, even.
| pjs_ wrote:
| It has been possible to buy pretty nice handheld Raman
| spectrometers for a while now:
|
| https://www.bruker.com/en/products-and-solutions/infrared-an...
|
| This paper is obviously trying to go much further. But if you
| just want to buy a tricorder, you can
| multimoon wrote:
| I was unable to find a specific price for the model you linked
| in my few seconds of looking but these devices generally run in
| the $10,000 USD range, so I don't think it's achieved the "if
| you just want to buy it" territory yet.
| pjs_ wrote:
| Good point. You have to ask yourself -- would you rather have
| a '97 Camry or a raman spectrometer and a pushbike ;)
|
| That said this is getting into Christmas present territory:
|
| https://www.ebay.com/itm/167319991806?_skw=handheld+raman+sp.
| ..
| throwup238 wrote:
| I love the juxtaposition of thinking a '97 Camry is
| anywhere close to $10k while at the same time a $3k piece
| of lab equipment is "Christmas present territory" :)
|
| It's one banana, Michael. What could it cost? Ten dollars?
| Loughla wrote:
| It is genuinely disheartening when people in this board
| start talking about things they buy when they're WILDLY
| out of my price range. It's almost like living in a
| flyover state and working in education isn't optimal for
| income. Weird.
| pjs_ wrote:
| Dude I have three thousand dollars net total in my bank
| account. I don't own a car or a house, don't have kids
| etc. I literally used to co-own 97 camry with bees in the
| trunk. I paid about $2500 for it. Hence why I say it
| costs the about the same as the spectrometer on eBay.
| $2500 is about $3000. However you and I both know that
| there are people all over this board who buy their kids
| macbooks for christmas
| LoganDark wrote:
| > there are people all over this board who buy their kids
| macbooks for christmas
|
| Kids? I bought a MacBook Air for an internet friend of
| around 2 months because I was so offended by the fact
| that they didn't own a good computer.
|
| My performance standards are higher for myself of course,
| but the goal was just to get them any form of macOS.
|
| (They did in fact end up liking it a lot better than
| Windows)
| reaperducer wrote:
| _Laser-based device can scan almost any sample of gas_
|
| Oh, sure, it can tell you who smelt it. But the real money is in
| figuring out who dealt it.
| Vox_Leone wrote:
| Why this progress is significant for AGI:
|
| Multi-Sensory Integration: Traditionally, AI models have been
| trained on a limited set of sensory data, mainly acoustic
| (speech, sound) and visual (images, video). Adding chemical
| (olfactory) and tactile data allows AI to engage in multi-sensory
| integration--mirroring human perception much more closely. This
| can help machines interpret the world in a more holistic way, as
| humans do, where smells and touch inform emotional responses,
| memory, and decision-making.
|
| Challenges:
|
| Data Collection and Tokenization: Tokenizing chemical signals and
| tactile sensations in a way that AI models can understand is no
| small feat. With smells, for example, creating a "universal"
| vocabulary or set of descriptors that an AI can use might require
| advanced pattern recognition and mapping of these signals to
| emotions, objects, or experiences.
|
| Complexity: The integration of multiple senses is complex, and it
| might take time to fully understand how chemical and tactile data
| interacts with visual and auditory data to form a coherent model
| of the world.
|
| + Ethics and Privacy
| mannyv wrote:
| Contamination?
| akomtu wrote:
| Can it detect the amount of PFAS in tap water?
| Beijinger wrote:
| Sounds trivial. Without opening the link, let me guess: QCL?
| amelius wrote:
| Can it detect medical disorders, similar to how (according to
| popular belief) dogs can smell cancer?
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