All Over But the Funding: Open Hardware Spectrometer Kit

Finally! by ColdWetDog · 2012-09-21 16:46 · Score: 4, Funny

A use for all those Windows ME disks!

(You need a DVD as a diffraction grating.)

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Faster! Faster! Faster would be better!

Re:Finally! by Alwin+Henseler · 2012-09-21 17:29 · Score: 1

DVD != CD (and in case those Windows ME disks are originals: DVD-R != CD-ROM)

Funding? They're way over! by billstewart · 2012-09-21 16:53 · Score: 2

Ok, they've got a few days left, but they've currently got $72000 vs. their $10000 goal. Cool project, interesting applications.

(But since we're talking Kickstarter here, I'd like to put in a plug for the Drip Clip kickstarter. They've designed a small drip-counter to be used for measuring medicine in intravenous bags, especially for applications like disasters, third-world hospitals, and the like. The prototype used Arduinos and baling wire, but the production version is going to be manufactured plastic with a simple count-down display on it.

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Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks

Pretty cool ... by RockDoctor · 2012-09-21 16:55 · Score: 5, Interesting

That's an interesting combination of technologies and materials. The basic idea should be workable, but how workable they'd be for material identification given the prevalences of IR filters on (consumer grade) CCD sensors and their relatively low sensitivity ....Identifying spectral lines on a 10-bit sensor is difficult enough. Trying to do it on the 7-8 bits that you get from a (consumer grade) sensor ... is going to be more difficult.

But ... that's an interesting idea. I think that's worth a six-pack worth of funding.

Did I get a first post? Are the trolls and the GNAA spammers asleep? Or, preferably, dieing slowly?

--
Birds are not dinosaur descendants;birds are dinosaurs, for all useful meanings of "birds", "are" and "dinosaurs"

Re:Pretty cool ... by dns_server · 2012-09-21 17:31 · Score: 4, Informative

One of the steps of building the kit is removing the IR filter from the webcam.
Re:Pretty cool ... by thegarbz · 2012-09-21 20:19 · Score: 4, Informative

I have converted consumer junk to remove IR sensors on many devices from simple webcams to high end DSLRs. It is simple.
The hardest part about the process on cameras is working with tiny ribbon cables and sourcing replacement optics if you wish the resulting camera to operate again (since removing the filter completely will result in your camera becoming nearsighted.
Neither of these are a problem with webcams, and the only issue you're likely to have is that some webcams have their filter glued onto the CCD rather than just placed on and retained with a small amount of pressure from the case.
Re:Pretty cool ... by hardie · 2012-09-21 22:31 · Score: 1

Actually, it IS workable. Check out the link.
Re:Pretty cool ... by drooling-dog · 2012-09-22 02:45 · Score: 3, Insightful

Trying to do it on the 7-8 bits that you get from a (consumer grade) sensor ... is going to be more difficult.
True, but if you're imaging the spectrum in two dimensions and summing/averaging vertically (over columns), you'll improve your Signal/Noise ratio considerably (by the square root of the number of vertical pixels, ideally). It wouldn't surprise me if the results were quite decent.
Re:Pretty cool ... by Anonymous Coward · 2012-09-22 05:30 · Score: 2, Informative

The bit depth of the sensor is more or less irrelevant. Spectral accuracy is a function of their diffraction grating and the size of the sensor: it's a spatial effect, not a detection/encoding one.
The bit depth does matter for sensitivity and dynamic range. For sensitivity, the dark noise of the sensor is also important, since you can effectively average for a very long time.

Spectrometers can get you tail! by Anonymous Coward · 2012-09-21 16:57 · Score: 5, Funny

Back when I was in University in 2001 (U Waterloo - Independent Studies) one of the guys found a spectrometer for sale at the weekly physical plant surplus sale for fifty bucks so he just set it up in the IS lounge (which was in the middle of the Psych building) so people could come in and analyze whatever they wanted. It was great for inviting hippies in to charge up crystals with very specific wavelengths to increase harmonic resonance.

Thousands of dollars? by Anonymous Coward · 2012-09-21 17:31 · Score: 0

How about 10 bucks?

http://www.rapidonline.com/Education/Spectrascope-kit-71984

Re:Thousands of dollars? by Anonymous Coward · 2012-09-21 17:35 · Score: 1

digital spectrascope = spectrometer. $10 for a spectrascope is actually a bit of a ripoff.
Re:Thousands of dollars? by Anonymous Coward · 2012-09-21 18:16 · Score: 0

Well, quite. And the one that you get if you pledge $10 on this kickstarter is made of cardboard.

Re:Funding? They're way over! by SomePgmr · 2012-09-21 17:41 · Score: 2

I pitched in (and hope to get one of these), after having done one of the online instructions for a very rough looking one. It seems like the sort of thing that will net me hours of goofing off for very little money. ;)

That Drip Clip sounds pretty cool, though it looks like it's IndieGoGo, not Kickstarter: http://www.indiegogo.com/shiftlabs

Unfortunately, $75 is a bit out of my funding range. Otherwise it'd be a nice little sensor to play with.

I freeken love this. by Anonymous Coward · 2012-09-21 18:11 · Score: 4, Informative

I did my PhD on a topic that involved building some gear related to spectroscopy. A good deal of my work involved cludging together optical parts from seemingly unrelated sources. As such I just love this sort of thing. Unfortunately I have to agree with the above commenter that the precision is just not going to be good enough from a webcam for real chemometric measurement. However with a little more investment the precision could be improved. The real difficulty will come from the need to calibrate the thing. You need to know exactly where each wavelength of interest is centred ** exactly** on the sensor at the time of measurement and this is not a trivial task. Unfortunately proper calibration is so often just not achieved... and that's not even beginning to consider the issues of background/ stay light, Johnson noise etc. I suppose this design could be used for crude detection like the article says rofl.

Re:I freeken love this. by Anonymous Coward · 2012-09-21 19:08 · Score: 3, Interesting

What is interesting about talking to researchers about spectrometers, is there is quite a diverse spread of priorities and needs depending on what they are doing. The work I did required a significant amount of time calibrating several aspects of the spectrometer (intensity and response calibration being typically much more annoying than just the position of lines). I would discuss calibration methods with other researchers at conferences, and be thinking, "How primitive, you would barely be able pass an undergrad lab with calibration like that ... oh, that is what is being used for... yeah, there isn't much point in putting more effort into." Yet at the same conference I would pump into people on the other end, who likewise were thinking along the lines of "Oh, you only spend a few hours calibrating a day and didn't take into account all these shifts and broadenings... oh, those are are a tiny fraction of a pixel on your detector."
There should be room for fun at all levels of capability (ok... more advanced spectrometers may be more tedium than fun...). If this project isn't enough, adding another zero on the price starts to get into various commercial USB spectrometers available. Those are pretty compact and self-contained, although software almost universally sucks. The only negative potentially being a slightly larger influx of crackpots whos discoveries are actually bad calibrations... I've had more than one cold contact along those lines where their spectra were clearly components of air with a slight offset due to bad calibration.
Re:I freeken love this. by Anonymous Coward · 2012-09-21 20:25 · Score: 3, Informative

This is the same AC that you replied to. Yeah, every time one little part got changed on our $100,000 units the whole thing had to be re-calibrated for response factors. Then they would break down all the doggam time. Fibres would break or a microchip might come unseated and I wasn't allowed to touch the insides. Not to mention the cost of the reference reflectance tiles being a little bit more than the average bathroom ceramic.
As for the crackpots and bad calibrations, I thought my head would fall off from shaking it in disbelief at some of the results people touted as 'significant'. Just because data can pass a t-test doesn't mean that R^2=.4 is useful(!) Especially when there's no future proofing the the method. And don't get me started on some classification results. Poor linearity is just not a good excuse to revert to just setting threshold.
Re:I freeken love this. by photonic · 2012-09-22 00:02 · Score: 4, Interesting

Optics guy here too. I don't know a lot about spectroscopy, but I had to assemble a spectrometer for my thesis project. It was a pretty fancy imaging spectrometer (main element was a concave mirror and grating combined in one) and used a LN-cooled CCD as the sensor. This was not cheap stuff (~5000eu for the spectrometer and probably > 20000eu for the camera), but the operating principle is exactly the same as the DVD + webcam. The resolution was limited to around 1 nm due to the input slit, not sure if they could improve things by using a slit in this home-built device. I had to calibrate it from scratch, which was actually pretty easy: I borrowed some spectral lamps from the 1st year lab course and also used a HeNe-laser we had laying around. Choose a few of the big lines (which should all be known to better than 1 nm) and for each write down the pixel position of the line on the CCD. Perform low order (e.g. quadratic) polynomial fit and you are done calibrating. I don't know if there are some cheap spectral lamps that you could use at home, there is at least the yellow lines from the Sodium (?) street lightning. I agree with others that the resolution of these home built devices is probably too low to identify materials, but it is for sure a fun project.

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Re:I freeken love this. by Atraxen · 2012-09-22 01:21 · Score: 2

True - but for a homebrew quality spectrometer, using a green laser pointer can at least provide a two-point calibration (the 1064 and 532 lines - at least for cheap laser pointers with garbage IR blocking filters - www.nist.gov/customcf/get_pdf.cfm?pub_id=906138). You could probably get clever and determine the central lambda-max for the red and blue diode lasers but using the distance between 0th, 1st, and 2nd order diffraction spots off a grazing/dvd to get an ok value for it - but boy, these calibrations are adding up!

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Be careful of your thoughts; they could become words at any minute...
Re:I freeken love this. by mybluevan · 2012-09-22 02:23 · Score: 1

Some of the people that have early prototypes are claiming 1nm precision. They've mainly been using CFLs for calibration because of the variety of consistent spectra points and how common they are. Not lab grade, sure, but decent enough for home use.
Re:I freeken love this. by zippthorne · 2012-09-22 02:43 · Score: 2

For a homebrew project, you're going to want to calibrate it using things you have easy access to. Things that are found in nature, perhaps. There must be a clever way to avoid having to borrow or obtain a lab-grade arc lamp. Perhaps using a CFL and the right filtering? I'm not sure how monochromatic each of the phosphors are...
Maybe accurate calibration isn't necessary, and just using the peak wavelengths from the sun and a halogen lamp would be sufficient to get a rough calibration using wein's, assuming both peaks are in the range, and the second order reflections don't mess things up too much.
Atraxen's idea looks pretty good.
I've often thought that the cd/dev as cheap diffraction mirror for school projects and demos would be a great idea and I hope there have been some science fair projects using the principle. I just wish I'd thought of doing a kickstarter so I'd get the credit...

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Can you be Even More Awesome?!
Re:I freeken love this. by Anonymous Coward · 2012-09-22 03:54 · Score: 0

The noise could be reduced in two (similar) ways:
1) If the spectrum is projected to cover the entire
sensor, then average all the pixels in each vertical
line. The noise from the sensor elements will tend
to average out to zero.
2) Take multiple images of a spectrum and save their
average. This would reduce the noise in the same way
as above.
Both of these methods would increase the amount of
usable precision.
Re:I freeken love this. by Anonymous Coward · 2012-09-22 06:58 · Score: 1

(AC you replied to... AC #2, or second ... shut up, I'm lazy about registering...)
We basically did full calibrations in the morning and evening of every day we ran, assuming we didn't change the narrow spectral range we were looking at. We wanted to be sure no one bumped the spectrometer or fibers, and that it wasn't affected by changing temperature, or the experiment itself (pulsed plasma experiments kind of wreck havoc on equipment). But if we needed to change what wavelengths it was looking at, that meant recalibrating... and there were some wavelengths we couldn't look at as appropriate calibration sources were not available for the spectral range and within a limited budget.
Although I was lucky and only needed relative response and intensity calibration between several inputs. The grad student doing research that required absolute calibrations ... let's just he was lucky he was anal-retentive, and even then spent years getting things right. Also I guess you could say I was lucky that the bulk of the spectrometer was WW2 era, so I could mess around with the insides and alignment all I wanted. The only parts that had to be modernized were the grating and camera.
Re:I freeken love this. by Anonymous Coward · 2012-09-22 07:17 · Score: 1

Sometimes the bottleneck is elsewhere, but typically in my experience with spectrometers, the limit to your resolution is the camera or the grating... and not necessarily in the most obvious sense. In many cases it doesn't take much camera resolution to the point smaller pixels won't help (I've used enough high end spectrometers where their 640x480 sensor had more pixels than was useful). Two quick ways to increase resolution would be to narrow the slit and to increase the length the light goes to give it more space for the angles to spread out. Narrowing the slit shouldn't be too hard, as jury-rigging something on par with a professional spectrometer is not too hard (at the cost of stability and easy of use). The problem with both of those options, is they will quickly lower the amount of light getting to each pixel in the camera.
What becomes really important is the light sensitivity of the camera. This is why you will see a lot of cooled cameras for spectrometers that can take long exposures, or intensified CCD cameras for high speed spectroscopy, or even photomultiplier tubes. There have been plenty of times where I wanted more resolution, but was limited
Additionally, the grating will eventually limit your resolution. The resolution in some typical configurations is roughly proportional to the number of lines on the grating being hit. You can improve resolution by either increasing the line density of the grating, or spreading your light over a larger grating. Larger gratings get expensive fast...
Re:I freeken love this. by Anonymous Coward · 2012-09-22 07:35 · Score: 1

Lasers would be pretty good for a strong, known light source for rough calibration (10 nm... maybe 1 nm resolution). But, along with LEDs, their wavelength and spectra are not as stable and consistent as some people think. I've used LEDs to calibrate equipment before, although that was only after measuring and determining their spectra with another spectrometer that was calibrated from other sources. Sometimes even LEDs within the same batch varied by 10-20 nm for their peaks, which is good if you want more data points, but bad if were to assume they were as labeled.
And depending on the optical arrangement, especially for a spectrometer covering the full visible spectrum, you would want at least four or five data points for wavelength calibration. It is really easy for cubic corrections to the calibration to blow a 1 nm resolution. Higher order lines might be useful, although might be wasting some pixels on the cameras, and their intensity might drop off a lot.
An easy calibration source might just be to use a fluorescent light. Just make sure to use the mercury lines,and not the lines from the phosphors. You might be able to get a germicidal mercury lamp to make it easier (but wear eye protection...). Or if your budget is not super constrained and it is important, you could probably make the jump to spectral lamps for under $100 with a bit of careful shopping, and those are used to calibrate wide range of "serious" spectrometers.
Re:I freeken love this. by Anonymous Coward · 2012-09-22 10:09 · Score: 0

A better approach to taking multiple images, is to
vary the illumination over a range which is just large
enough to affect the least significant bits of the
intensity values. This will allow approximation of an
additional bit or two, depending on how many images
are taken.
Re:I freeken love this. by Anonymous Coward · 2012-09-22 14:29 · Score: 0

Although it really depends on the application, at least for spectrometer work I've done before, those last few bits didn't matter anyways. I've used 10 and 12 bit cameras, but it was difficult to get much more than 8 bits of dynamic range anyways because of noise. Simply summing many images was all that was needed to clean up noise when the spectra was reproducible, no variation really needed.
Re:I freeken love this. by Anonymous Coward · 2012-09-25 06:58 · Score: 0

It would be better if it was an ablative mass spectrometer that could analyze opaque solids. I guess that's another Kickstarter...

Unclear on the concept by subreality · 2012-09-21 18:41 · Score: 1

"Open hardware" "limited edition" ... I'm pretty sure someone doesn't understand how this works. :)

Re:Unclear on the concept by jywarren · 2012-09-22 02:36 · Score: 2

The brass-and-wood "steampunk" version is limited edition, but only limited in that we're only selling 5 pre-built spectrometers. The designs are already online for most of these models and based on the early build photos and bill of materials you can build your own (under the CERN Open Hardware License). So it is open hardware -- have fun!

No Shazam at these wavelengths by Anonymous Coward · 2012-09-21 18:46 · Score: 0

There is no practical way to make it do "SHAZAM" in the 400-900 nm range these guys target. Especially with the claimed 10 nm spectral resolution.
Generally speaking, Shazam-like identification is very much practical in the NIR or IR ranges, not so much in visible or UV.
I also kind of cringe at the mention of "toxins" in TFA. Those guys have no idea whatsoever about what they are doing.
Yes, I am a chemist.

Re:No Shazam at these wavelengths by shaitand · 2012-09-21 19:02 · Score: 1

They do have additional information about removing the IR filters from the camera. Should improve the spectrum.
Re:No Shazam at these wavelengths by Anonymous Coward · 2012-09-21 21:23 · Score: 2, Interesting

Not nearly enough.
Near IR (900-1300 nm) is the best you can hope for with a camera chip as a detector. Yes, you can sort of/kind of do a bit of "fingerprinting" there, but 10 nm spectral resolution won't cut it for this kind of application. On a side note, I seriously doubt they can get 10 nm from a CD as a diffraction grating.
To go for the traditional IR fingerprint region, they will need to look at the region between ~6000 and 20000 nm, which is decidedly not something you can do with a webcam chip. You need a *very* special kind of sensor for that. For the reference, a reasonably specced IR spectrometer will cost a tad over $10K. Most of this money will go towards the hardware, that is the sensor and the optical bench.
I wish it was really possible to identify "toxins" with a simple visible light spectrometer. I have one of these el cheap machines in my lab:
http://www.chemglass.com/product_view.asp?pnr=CLS-4047
They are only useful for measuring concentrations of very, very specific compounds under very specific conditions. We also have an $15K IR machine, as well as two mass spectrometers and routine access to 7-8 $1M NMR spectrometers. Sometimes this is enough to analyze practical samples, and sometimes it isn't.
When it is not working out for us, it is not a software problem.
It is clear to me that the people behind this project are, unfortunately, out of their depth.

Lots of work has been done here by Anonymous Coward · 2012-09-21 18:55 · Score: 5, Informative

Lots of people have been working in this field. The most impressive results are achieved by the astronomy community. link It is possible to produce a home made spectrometer that gets useful results. Some of these are capable of resolution sufficient to identify chemicals. These are sophisticated and often use a peltier cell to cool the CCD in order to reduce noise. link

I did a project whose aim was to produce a cheap spectrometer to match paint colors. link The problems I found were:

Cheap webcams are quite noisy
Cheap webcams are not at all linear
For dark colors, sensitivity is a big problem
The spectrum of the light source varies depending on which angle you view it from.
Organizing the data is perhaps the biggest problem of all

My own engineering trade-off was sensitivity vs. resolution. To get spectra for dark colored paints, I widened the slit which reduced resolution. That, as far as I could tell, was reasonable because I wasn't trying to identify chemicals and the spectra from paints weren't particularly sharp.

The folks in TFA have a site where people can upload spectra. That's fine but a huge database of spectra is not too useful. The spectra have to be organized somehow. Here's an example. In fact the problem can be quite daunting

Re:Lots of work has been done here by Anonymous Coward · 2012-09-21 20:52 · Score: 1

These are sophisticated and often use a peltier cell to cool the CCD in order to reduce noise.
It's really neat, but I wouldn't call it sophisticated. Thermal noise is randomness. Less heat, less noise. Up to a point, you could use ice or a cold climate to accomplish the same thing as a peltier. Or go further than a peltier and use cryogenic liquids and really maximize the SnR. (It's all slightly impractical.)
I've been playing around with an idea on the same topic as this story, but I haven't heard anyone else mention it before. Building a spectroscope using LEDs. Instead of emitting light, they're used as sensors inherently specific to their peak wavelength. Between 400-700nm, with a minimum of 10 distinct LEDs it would have a resolution of approximately 30nm (probably with some gaps in sensitivity). The problem is filling in the gaps, where no LED exists that can produce or detect the wavelength. The upside is they could detect a wider section of UV and infrared than a CCD. Add a display interface, throw in a photoresistor to measure the total light amplitude for calibration and Bob's your uncle. No need for narrow slits, diffraction gratings or other challenges associated with DIY spectrometers.
Re:Lots of work has been done here by drinkypoo · 2012-09-22 01:45 · Score: 1

These are sophisticated and often use a peltier cell to cool the CCD in order to reduce noise
OK, the peltier is going to cost ten bucks and need a twelve volt supply. Not a big deal. I bet they charge a lot for that though :)

--
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
Re:Lots of work has been done here by qvatch · 2012-09-22 03:56 · Score: 1

LEDs will still have a pretty broad spectral response so you'd have overlap, and need quite a bit of gain. Try one of the taos colour sensing chips, those do RGB+all with programmable gain and digital output, it'll make the project pretty simple and much more repeatable. you can also do one clear NIR phototransistor with selectable filters for colours. That'd be manageable. For my project, I am using, currently, a clear phototransistor and illuminating the target with a specific LED colour. I think someone has done something pretty similar (but reflection rather than transmission) on instructables too, but I can't dig it up.
Re:Lots of work has been done here by Anonymous Coward · 2012-09-22 19:40 · Score: 0

LEDs will still have a pretty broad spectral response so you'd have overlap, ...
It's all about reversing the polarity (yay, it's true and I'm pandering to /.). Charging the parasitic capacitance of an LED and measuring discharge in the presence of its peak wavelength does not yield a broad spectral response, at all. I had problems in the past when I tried using LEDs as simple photodetectors; they weren't sensitive throughout the spectrum. The ambient lighting caused measurement errors with fluorescent vs. daylight/incandescent. The green and yellow LEDs failed to detect light at one foot away from a fluorescent bulb, but blue worked better, and red worked best (I don't remember the wavelengths of all the LEDs, but the red was 640nm, and blue was 470nm). The blue and red corresponded to the emission spectrum of the CFL bulbs tried, which *mostly why they detected light (*they also had some advantage in capacitance).

...and need quite a bit of gain.
It's a time measurement, there's no gain. With just an Arduino, it's easy to build this type of circuit. Others already have. It uses a resistor to control the RC time constant; increasing the duration to something measurable in microseconds - not amplitude.

Try one of the taos colour sensing chips
Not if I can help it. Mainly because LEDs are cheaper. And a proprietary component for the sake of simplicity makes me die a little inside. It's funny how simplicity often turns out to include a hidden catch-22 or conveniently undocumented feature.

Can it detect radioactive isotopes? by Anonymous Coward · 2012-09-21 20:16 · Score: 0

For example. Cs 137 in food?

Re:Can it detect radioactive isotopes? by Anonymous Coward · 2012-09-21 21:26 · Score: 1

Sure, if the concentration is high enough. Strongly radioactive samples are known to glow in the dark:
http://spectrum.ieee.org/energy/nuclear/nuclear-wasteland

First picture on their page failed the idiot test by thegarbz · 2012-09-21 20:23 · Score: 3, Interesting

Really the very first picture they showed of the spectra and the resulting plot on the very top of their kickstarter page has the graph backwards compared to the visible spectra.

With such an epic facepalm I'm surprised they know what a spectrometer is.

Booring... by Kazoo+the+Clown · 2012-09-21 23:03 · Score: 1

Wake me up when they get to a homebrew ultrasound imager, or something a little more interesting. Or at least a spectrometer that works off lazer burn at a distance and built into a portable point-and-shoot unit you can walk around with.

Cringe-worthy by threeplustwo · 2012-09-21 23:23 · Score: 3, Informative

I don't want to sound all negative here, but... I don't have a choice, do I? A visible light spectrophotometer will not "detect toxins", no matter how much you try to make it open-source or crowd-sourced. The very concept of identifying compounds by visible light absorbance is very much flawed. Thing is, *most* molecules will not absorb visible or near UV light in a way that is specific enough. Real Chemists (TM) traditionally use the so-called IR fingerprint region for this purpose. This region is from approx. 700 to 1500 cm-1 (about 6 to 20 uM - that is 6000 to 20000 nanometers). A special detector is needed for these wavelengths. The one we have in our lab is cooled with LN2 and costs south of $15K. We also have a UV-Vis spectrophotometer, which has its own purpose. That purpose is not "identifying toxins", or analyzing any unknowns. Now, on to my next point. Identifying molecules is challenging, because they are very, very, very mindbogglingly small. Chemists have been grappling with this challenge for a long time. There are many spectrometric methods out there, including IR and UV-Vis (briefly discussed above), near-IR (900 to ~1800 nm, useful for *some* fingerprinting), and NMR (60-1000 MHz, very informative, bit needs a BIG magnet). Spectral data for many molecules of interest has been compiled into readily accessible databases, and is easily accessible. Some of the databases are proprietary/pay-per-view: https://ftirsearch.com/features/libraries/sea407.htm Some are semi-public: http://riodb01.ibase.aist.go.jp/sdbs/cgi-bin/direct_frame_top.cgi And some are government/public: http://webbook.nist.gov/chemistry/ The people who started this project do not seem to grasp of the very basic concepts of chemistry, nor did they do any research on the subject. Reading a Wikipedia article on UV-Vis would have been a good start. What is even more disconcerting is that the fundraising effort behind this cardboard spectroscope has been a success. One just has to hope that nobody buys this to screen their food for "toxins", or to teach their kids chemistry.

Re:Cringe-worthy by jywarren · 2012-09-22 02:28 · Score: 3, Informative

Hey threeplustwo -- actually there is pretty good literature on laser fluorescence spectroscopy of polyaromatic hydrocarbons in the near-UV to visible range, you should check out some of the Public Lab research notes on the subject: http://publiclaboratory.org/notes/warren/7-18-2012/fluorescence-oil-spill-residue-diverse-spectrometer-use with longer exposures we are able to get a clean read on the fluorescing spectrum. And even in the shorter term (before these harder uses are better developed and more rigorous) there are plenty of applications that are already feasible and useful. Check out the use cases highlighted in the KS Updates -- one guy used it to detect brighteners in laundry detergent, others are using it to empirically test grow lamps in aquaponics, etc etc.
Re:Cringe-worthy by threeplustwo · 2012-09-22 02:58 · Score: 1

Sure, fluorescence spectrometry is pretty useful. So is UV-Vis. In my lab, I use the latter to estimate the size of gold nanoparticles we are making (there, I said the "nano" word!). We use a cheap-ish Lambda XLS+ machine built by Perkin-Elmer. However, there is a very big gap between observing fluorescence of PAHs (not really possible with their specific setup) and the sweeping claim that they "...imagine a kind of 'SHAZAM for materials' which can help to investigate chemical spills, diagnose crop diseases, identify contaminants in household products, and even analyze olive oil, coffee, and homebrew beer." Sounds more like something that can save the world and change lives, and less like a useless (and poorly executed) toy it is. Sometimes, real science can be done by gifted amateurs in their backyards. Sometimes, you actually do need to go to grad school and then spend $2M to outfit a lab. Building a real spectrophotometer and (more importantly) interpreting the results requires the latter.
Re:Cringe-worthy by gillbates · 2012-09-22 09:54 · Score: 1

It seems you're burning a straw man. The project goals were not to "detect toxins" in the general sense, but to detect the presence of certain chemicals with a well-known, easily identifiable spectrum.
And your bit about molecules being "mind bogglingly small" is irrelevant. Such a limitation didn't prevent 18th century chemists from discovering the elements, and is not likely to pose a problem for the spectrometry crowd, either.
Naturally, it is easier to detect the spectrum of something for which you have a large sample, hence the lackluster initial goals. But this could be used - or something similar - with even a moderately-sized telescope (75mm or larger) to do spectra of the planets. Which is the likely final direction of this project.
They might have to use something other than a CCD, though. But I would think it could be done with a 10 cent CdS photocell and a prism - but that's just me. (The mechanical part would be more challenging, though.)

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Re:Cringe-worthy by Anonymous Coward · 2012-09-22 18:25 · Score: 0

Some useful information but you forget to mention about the diffculty in interpreting mixed spectra and the statisical challenges involved in handling real samples. From the hardware point of view though don't bother making stuff yourself...you dont have the right attitude to look outside the box to solve an engineering problem.
Re:Cringe-worthy by threeplustwo · 2012-09-22 20:58 · Score: 1

Read the TFA, if you have not yet.
"We are working on a cheap version which we hope to use to identify oil contamination in water and soil, as well as a range of other possible toxins."
It is in the first paragraph, right at the top of the page. I did not invent it. Also, they are trying to make an absorbance spectrometer. It has nothing to do with planets or astronomy.
I would not call their goals "lackluster" either. I wish I had something like that in my lab. Problem is, the execution is very poor. The guys behind this are really clueless, to the point of having visible light spectra on their Kickstarter page backwards.

Blood sugar test? by tstrunk · 2012-09-21 23:33 · Score: 2

Disclaimer: I'm no expert in spectroscopy.

Would it be possible to estimate the blood's sugar content with this kit?

It is possible non-invasively with Raman spectroscopy in the infrared:
http://www.popsci.com/technology/article/2010-08/mit-glucose-meter-checks-blood-sugar-levels-painless-ir-light

The usual blood glucose meters have errors of up to 50% in the reading. And they still require those expensive analysis strips.
If a home blood glucose measurement would be possible with one of those kits (even if you still need to draw blood), that would rock.

Re:Blood sugar test? by threeplustwo · 2012-09-22 03:09 · Score: 3, Informative

Non-invasive glucose measurement is one of the holy grails of portable spectrometer design. As it happens, it is most practical using NIR and IR. There are products that will be on the market soon. The kit from TFA won't do it, of course. Spectral resolution is too low, and it looks at all the wrong wavelengths.

Re:First picture on their page failed the idiot te by Anonymous Coward · 2012-09-22 00:43 · Score: 1

Backwards? You mean because light always increases wavelength from left to right?!
Maybe it is just in an unconventional "direction" because the sensor captures it that way?

epic facepalm indeed

Re:First picture on their page failed the idiot te by thegarbz · 2012-09-22 01:39 · Score: 1

No I mean backwards in that the image of the spectra doesn't line up with the actual spectra immediately underneath it. It doesn't matter which way it runs, but one would think if you're advertising a system which gives you a spectrum from an image you'd at least line them up so they both face the same way.

Re:Funding? They're way over! by mybluevan · 2012-09-22 02:44 · Score: 3, Interesting

They've got an interesting stretch goal though: "if we get to $100,000 -- a 'stretch goal'. In the spirit of enabling open collaboration we'd like to make it possible for people to make their own Spectral Workbench-based apps". I'm thinking a Spectral App Platform API would be pretty sweet. "Imagine a "Spectral App Store" where wine enthusiasts can develop their own testing suite for wines, gardeners for grow lamps, and coffee connoisseurs for coffee -- each looking for specific wavelengths or patterns *specific to that application*." They're not that far away from it either.

great for teaching. by Anonymous Coward · 2012-09-22 04:01 · Score: 1

this is awesome! I may not be able to support papers to chemistry journals with it, but for teaching people how different colors of light split up into wavelengths with a prism, this is perfect. I've spent some time showing people how to use spectrographs (the black tubes) to see wavelengths of flourescent lights and LEDs and it's kind of a pain to teach them how to see in the edges of the tube. However, with this kit, everything's already aligned and I can bring the pix into a computer to show a scale drawn on top of the pictures. Pretty useful for showing a bunch of people at the same time!!!

Speaking of crude detection by dbIII · 2012-09-22 04:21 · Score: 3, Interesting

As late as the 1990s I used a portable optical spectroscope with a battery to strike an arc and a book full of photos showing where the lines should be for specific elements for alloy identification. I only used it a couple of times and didn't get the hang of it, but apparently some people got useful results from it to the point of estimating percentages of elements instead of just seeing if they were present.

Useful for homebrewers? by mad_ian · 2012-09-22 10:38 · Score: 1

So... Can I use this to determine the alpha and beta acid levels in my homegrown hops?

--
~Donald / Just RTFM

Re:Useful for homebrewers? by Anonymous Coward · 2012-09-23 03:20 · Score: 0

No. Quantitative work with this kind of setup is probabbly hard enough not to mention that your target compounds probablly absorb in the UV range and definitly overlap with their absorbance bands.

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All Over But the Funding: Open Hardware Spectrometer Kit

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