Spectrometry
question:spectrometry

The Public Lab spectrometry project is an open source community effort to develop low-cost spectrometers for a range of purposes. All open spectrometry hardware and software efforts are welcome here! **Join in by:** * Learning [what spectrometry is](#Whats+spectrometry) * Reading about goals and [asking great questions](#Frequently+Asked+Questions) * Building a basic spectrometer using [one of our starter kits](#Starter+Kits) * Trying (and critiquing) our [community-made how-to guides](#Activities) and posting your own * Building on others’ work; hack and remix the kits to refine and expand them * [Share your upgrades](#Upgrades) for others to try -- and perhaps for inclusion in an upcoming starter kit release or add-on kit **** ## Starter Kits Public Lab’s Kits initiative offers several starter kits, including many of the basic components, and instructions for constructing a basic visible light spectrometer. The point of the kits is to provide a shared reference design for building experimental setups onto. Lego Spectrometer Kit Our most recent kit, incorporating community improvements while balancing low cost and ease of construction. Choose between webcam and Raspberry Pi camera versions and build attachments width standard Lego connectors. Build one Buy one Papercraft Spectrometry Intro Kit A $9 paper spectrometer which you can attach to a smartphone or webcam. It’s made of paper to reduce cost and complexity, and is mainly intended as an “introductory” or educational kit. The flat design can be printed on a laser printer or photocopied to make more. Build one Buy one **** ## Activities This is a list of community-generated guides for specific applications using your spectrometry setup (either a [starter kit](#Starter+Kits) or a [modded design](#Upgrades)). These [activities can be categorized](https://publiclab.org/wiki/activity-categories), and some may be more reproduced -- or reproducible -- than others. Try them out to build your skills, and help improve them by leaving comments. Together, we can repeat and refine the activities into experiments. > **Note:** If you are working on an **urgent issue** such as a threat to your or someone else’s health, please know that these techniques may not be ready for your use; it's possible that they never will be. [Read more here](/notes/gretchengehrke/09-29-2016/common-low-cost-technique-limitations) ### Activity grid [activities:spectrometry] **** ## Upgrades Have you added to your starter kit, improved it, or redesigned it? Show others how to take it to the next level by posting a build guide here: [upgrades:spectrometry] Add your upgrade guide here Request or propose an upgrade _Mods should include a parts list and a step-by-step construction guide with photo documentation. See an example._ **** ## Challenges We're working to refine and improve DIY spectrometry on a number of fronts; here, take a look at the leading challenges we're hoping to solve, and post your own. For now, we're using the Q&A feature, so just click "Ask a question" to post your own challenge. Be sure to add: * constraints: expense, complexity * goals: performance, use cases [questions:spectrometry-challenge] **** ## Builds There’s a lot going on in open source spectrometry -- if you’ve developed another open source design you’d like to show others how to construct, post it here! * [RamanPi](https://hackaday.io/project/1279-ramanpi-raman-spectrometer) * [Hackteria “drop”-style spectrometers](https://publiclab.org/notes/gaudi/04-03-2014/diy-micro-volume-spectrophotometer) / [DIY NanoDrop on Hackteria.org](http://hackteria.org/wiki/index.php/DIY_NanoDrop) * _Add yours here_ ##What's spectrometry? Colored light is often a blend of different colors. A spectrometer is a device which splits those colors apart, like a prism, and measures the strength of each color. A typical output of a spectrometer looks like this spectrum of the daytime sky, with the actual light spectrum at the top and the graph of wavelength (horizontal axis, in nanometers of wavelength) and intensity (vertical axis) below: [![sky.png](https://i.publiclab.org/system/images/photos/000/005/455/original/sky.png)](https://spectralworkbench.org/analyze/spectrum/19882) > Needed: overview of spectra, calibration, units, comparison, and fluorescence/absorption. Please edit this page or link to a resource, potentially [the Wikipedia page](https://en.wikipedia.org/wiki/Spectroscopy), although that's quite full of technical jargon. ## Software Spectral data can be analyzed with https://spectralworkbench.org to create spectra plots, find centers of emissions plots, and find similar spectra. Data also can be exported in various formats (JSON, CSV, XML) for further analysis and visualization. ## How does this compare to a lab instrument? The [Desktop Spectrometry Starter Kit](/wiki/desktop-spectrometry-kit-3-0) is only one part in an experimental setup, and the following shows where it fits in an overall diagram of a lab spectrometric setup: [![tmp_31873-IMG_20161027_101601_2-79757779.jpg](https://publiclab.org/system/images/photos/000/018/635/large/tmp_31873-IMG_20161027_101601_2-79757779.jpg)](https://publiclab.org/system/images/photos/000/018/635/original/tmp_31873-IMG_20161027_101601_2-79757779.jpg) [![tmp_31873-IMG_20161027_095939_2-108076392.jpg](https://publiclab.org/system/images/photos/000/018/636/large/tmp_31873-IMG_20161027_095939_2-108076392.jpg)](https://publiclab.org/system/images/photos/000/018/636/original/tmp_31873-IMG_20161027_095939_2-108076392.jpg) There are many, many different types of spectrometry and spectrometers -- many don’t even measure light. Even among those that do, some detect light in the ultraviolet range, and others in the infrared range of light. The range of Public Lab spectrometers depends on the range of the commercially available cameras we attach them to (~400-700 nanometer wavelengths). A commercially available product with a slightly wider range (from 335 to 1000 nanometers) is [available from Cole Parmer](http://www.coleparmer.com/Product/Cole_Parmer_Visible_spectrophotometer_335_to_1000_nm_wavelength_range_analog_output/UX-83055-10). **** ## Frequently Asked Questions [questions:spectrometry] Note our previous Frequently Asked Questions page, which [can be found here »](/wiki/spectrometer-faq) -- please help port these into the new system, here!...


Author Comment Last activity Moderation
cfastie "Hi Sylvain, I don't know the answer to this question because I don't quite understand hyperspectral scanning. But I think the answer is maybe. The..." | Read more » over 8 years ago
interestedperson_ha "@all who gave a comment/ answer: Thanks a lot for your advice, sorry for my late reply. Since I regard myself as spectrometry-newbie reading the c..." | Read more » over 8 years ago
warren "I think that makes sense. I didn't mean Beer Lambert would be related to the reagent's affect on the color, but merely that if the reagent reacts l..." | Read more » over 8 years ago
stoft "It is my understanding that Beer's law is not the relationship between reagent's effect on color, but is the property of light passing through a un..." | Read more » over 8 years ago
warren "Oh yeah -- actually that's an open source method too, by Joshua Pearce's lab; you can find some of the parts here: http://www.thingiverse.com/thing..." | Read more » over 8 years ago
tonyc "check out this tool, using reagents: here may be what you are looking for? " | Read more » over 8 years ago
stoft "@warren has a good point; the smaller the change in transmitted light (as a function of attenuation caused by concentration change) the greater the..." | Read more » over 8 years ago
gretchengehrke "Hi @FoxClass, This is a great question. As the other commenters have mentioned, to compare intensities across different wavelengths, an intensity ..." | Read more » over 8 years ago
warren "However, if it's possible to either turn off exposure compensation between your two scans, or to scan both spectra at the same time (side by side),..." | Read more » over 8 years ago
warren "Yes, as @stoft mentions, an absolute intensity calibration is not required for demonstrating the Beer Lambert law; @mathew refers to a post about g..." | Read more » over 8 years ago
warren "Hello, what are you interested in specifically measuring, in nutrients? Nitrogen, potassium, phosphorus? I believe there are some colorimetric reag..." | Read more » over 8 years ago
stoft "The Beer-Lambert law primarily states there is a relationship between attenuation and wavelength of light through a substance. The attenuation is l..." | Read more » over 8 years ago
mathew "The spectrometer requires intensity calibration in order to detect color consistently. The active research is here: https://publiclab.org/notes/st..." | Read more » over 8 years ago
warren "Yes, it there should be an edit link (with pencil icon) under the "description" tab to do this. " | Read more » over 8 years ago
warren "Hmm, it looks like there's a bug in the "edit" link -- I've filed a fix and it will go up soon, but until then you can change the word "set" to "se..." | Read more » over 8 years ago
pdhixenbaugh "Hey Andrew, welcome to the public lab website! I'm actually curious about this too -and hopefully somebody will come by soon and let us know. You c..." | Read more » over 8 years ago
PeterDH "Thanks very much. That's the hint I needed, and I got calibration to work fine. Peter " | Read more » over 8 years ago
stoft "But that was part of my point -- the camera does 'raw-capture' processing on the sensor's 12-14bit detector data before it gives you the 'raw' data..." | Read more » over 8 years ago
cfastie "I think if you capture camera raw you have a single number (DN) for each pixel and you know what kind of Bayer filter that pixel was under. The DN ..." | Read more » over 8 years ago
stoft "Hmmm ... remember that the jpeg data is derived from MANY pixels which were run thoguht demosaicing from the RGGB filtered data, so unless you had ..." | Read more » over 8 years ago
warren "We'd have a lot more to work with if we knew which pixels were originally red vs green vs blue, and we could probably make more intelligent decisio..." | Read more » over 8 years ago
stoft "Sure. No, it's not a photon count, but it is related -- though the DSLR is attempting to extract data that represents a film negative. To do that, ..." | Read more » over 8 years ago
viechdokter "Thanx for explaining all this. Uhm, these "raw pixel data" you talked about, is THIS an electron/photon count? And if so, how long does the normal ..." | Read more » over 8 years ago
stoft "Right, the (R+G+B)/3 average contains all the camera can deliver. [Aside: There are, however, separate 'weighted' formulas for combining RGB to get..." | Read more » over 8 years ago