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.
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.
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.
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.
Oh. Don't bring up surgeons/ doctors in general on here. A shockingly large contingent of people believe the field is "gate kept by exams being too hard" -- which I'm pretty sure just means their parents wanted them to be doctors
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.
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.
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?
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]
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.
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.
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?
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.
I'm an IT that has ethics, so I haven't made good money, ever. Choosing not to harm, or, in your case, actively doing the opposite, I guess we'll just have to live with being able to sleep.
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
Hehe. Let me know if you have lived a whole life of only emotional neglect and abuse by narcissistic parents and if you share my exact autistic neurotype and maybe then we'll talk :)
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.
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.
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.
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.
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
>> 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.
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.
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:
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.
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.
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
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.
>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.
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.
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.
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.
1. It's harder to communicate with drivers with tinted windows and to check for their attention. This especially affects pedestrians and bicyclists who have to take pains to make sure they have a driver's attention before making their move, even when they have right of way.
2. You can't prosecute someone for a moving violation if they weren't identified as driving the car (because if a car is stolen for a joyride you don't want the original owner losing their license). Overly tinted front windows make it harder to consistently ID a driver, and let people get away with reckless driving.
3. Frankly it's annoying to not be able to see through cars. It makes certain turns iffier (because you can't see through the parked cars to identify oncoming traffic) and it makes it harder to predict a slow down if you can't see through the back windshield of the huge SUV completely obstructing your line-of-site. Obviously you should be maintaining a sufficient stopping distance to safely slow down, but that doesn't make it nicer to be able to see the slowdown/stop coming a bit before it arrives.
