Installing the software is easy enough. Go to http://www.ti.com/tool/dlpnirnanoevm and look around for a good list of manuals, install files, etc. The page could really use a clean-up, as many older files are mixed in with new files, and clutter up the web page. Overall, it easy to gain access to a lot of material, including the hefty 100 PDF user's guide. But the website is a bit overwhelming if you want to just plug in the device, install the GUI, and start scanning items.

In not reading this page properly the first time, I installed an out of date GUI.

The Update GUI has a lot more bells and whistles when you install the correct one!

Installing the software goes well enough, except for some out of date Firmware files.

If you really care, you can go back into the website, download more install files, go into the extract folders, and then point to the ISO and BIN files to update your firmware. This part is not very user friendly and poorly thought out.

When you open the software, you find a pretty well laid out application. There is a quick start page that arrives in the package for those eager engineers (me) who hate manuals and just want to play with the tech. It does a good job of getting you rolling and doing a first scan.

The manual and webpage mentions that there is an iOS app available for reading from this device. There is also an Android App available, but it must be quite new because it is not mentioned anywhere at all. You can find it here: https://play.google.com/store/apps/details?id=com.kstechnologies.NanoScan&hl=en. To setup with the app: Simply open the app on phone, turn on bluetooth, and then hold the Bluetooth/Scan button on the device for 3 seconds. When you see the blue light flashing, you can press the little icon in upper right that looks like an electrical cord connecting. Connection should happen pretty quickly. When you load, you notice they have pre loaded some different NIR signatures, to show you what the different spectra can look like, and to give you some ideas on things to go scan.

Let's get to actually scanning some goodies! The quick start recommends you just use the stock scanning parameters. All you need to configure is the save location and filename. Click Scan, and the device takes care of the rest. As mentioned above, the device will bath the mystery object in broad spectrum light (probably like an incandescent type light source), and the measures the light reflected by the object in each wavelength. The intensity of this received light is registered. From the intensity of this received light the device determines the light reflected by the object, and the corresponding light transmission through the sample can be determined.

My first scan was of an IR remote. It's a cheap little one with an IR LED, and I honestly didn't know what the beam profile would look like. I see the expected peak in the 900 nm range, but see several peaks, which I didn't really expect. At first I wondered if the light beam is coming out "choppy" due to the diffraction grating of the NIR DLP device. But I expect this is the true output, and that this is perhaps the noisy IR output of the very cheap IR remote.

I hooked up some other IR LEDs in a basic regulated circuit to verify the emission spectra. Below is a TSAL6200 IR LED. It should have a peak wavelength at 940nm.

I do the scan and get the expected intensity peak at 940 nm. This device is working! The software shows a cool display of the detector senses light reflected or absorbed, and also the light intensity received at each wavelength. What isn't working is this GUI software. The stock GUI software outputs a CSV of only the absorbance values, which are not interesting at all for an IR LED.

Testing some other materials on hand, we can see some interesting patterns.

Testing

I set up a basic testing setup in my kitchen and basically tested all the organic components of a charcuterie board, and different alcohols, for good measure. Because the device runs off a standard 5V USB, you can easily power it with a battery pack, and then control scans on your phone via Bluetooth connection. The app allows me to configure saving to the DLP micro SD card port or the phone. Very handy out of the box! Below I am scanning salt water.

This was definitely a very fun device to really dive into. After my software / firmware concerns, I was really able to get up and running, and start testing different fruits, vegetables, cheeses, and wines in my kitchen. This is definitely science. Delicious science.

Plant health

Looking at wet and dried Basil leaves, we can clearly see a difference. It's likely that the water content (and possibly other plant health factors) can be differentiated by the different NIR signature.

Not being much of a spectroscopy expert, I was a little lost on the difference between comparing intensity and absorbance. From looking at the manual, I think intensity might essentially be the raw power levels recording with the DLP. I think the absorbance (and correspondingly the reflectance) are a calculated, and better normalized value. With that in mind let's use absorbance values moving forward.

My wet basil has a peak absorbance at 1400 nm, while the dry basil has overall much lower absorbance values (look at y axis), and peaks are poorly pronounced, but visible at 1400nm and 900 nm. We can see a clear difference.

Comparing different types of veggies

Below is an orange. Honestly is visually hard to tell all of the produce apart just by looking at these spectra, but with a mathematical analysis I'm sure you could develop a decent finger printing method. In the image below I can see that there is a small local max just past 1580 nm, probably around 1650nm. I also see a deeper trough around 1085nm, or higher peaks around 1150nm.

Let's scan some fresh food and their packaged counterparts

Here is a fresh apricot. Right below it is apricot jam. Note that the signal appears noisier for the jam, but this is likely due to me scanning it through the glass jar (not wanting to contaminate my EVM). We can see that the 1400nm peak is relatively reduced, and there are higher readings across 1100-15nm. Part of this may be due to the glass (borosilicate glass should have low absorbance up past 2000nm), but a this should mainly be caused additives to the jam, such as sugar, pectin, and citric acid preservative.

Liquids

Let's review a couple other materials, and look at some liquids. I tried to take a NIR scan of regular water in a glass as a good baseline, but again ran into issues with my sample jar. I guess a well designed flat sample container would help mitigate these issues.

Looking at salt water, we see following absorbance.  Slight peak around 1400-1500nm, but generally quite flat. Noise is probably an issue.

Possibly because the bottle was quite clear, we got a great reading from our scotch sample.

Absorption is highest at 1085nm, and has a low point around 1150 nm.

I took a sample of black coffee, and got a different spectra. Their app has a spectra for coffee available, which ended up being very different from mine. This may be due to my extremely small sample size, as I was just emptying the remnants of my coffee maker.

A couple other items with markedly different absorption spectra.

Honey shows very different absorbance, with peaks at 950nm and 1200nm.

Flour shows strong absorbance only around 1400nm.

Crystals

Let's look at some sugar samples

White sugar has a sharp peak at 1700nm ish and a noticeable peak around 1450nm.

For Brown sugar we notice a very different peak profile, with a broad peak that spans 1450 to 1600nm.

Why all the peaks around 1400 nm?

In general I am seeing that most materials have a noticeable absorbance around 1400nm. Looking at spectral absorbance of light in our atmosphere I notice that almost all light in 1400nm range is blocked by water moisture in the air. This seems to be our explanation. The 1400 nm peak is attributed to water. In the dry basil, we see the remaining leftover water as a small peak but it is a relatively small peak compared to the baseline signal.

Conclusion

In summary, this was a great piece of hardware to get exposed to the hands on science of taking NIR spectroscopy measurements. This is a well designed piece of hardware, and the user is able to get the system up and running quickly, and take their first spectra readings within the hour. Most of the confusion comes from their online website, which confusingly serves up multiple versions of files, and there isn't even a newest version that contains all software and firmware together with the GUI. This one roadblock is enough to waste time of the purchasing engineer, who may be left questioning the device. But once you get the device up and running, this is a slick little product. Future updates to this product should include updates to smooth out the install process, the GUI layout itself, and the CSV export in windows, which at the point of writing still only outputs absorbance values only. The EVM pack would be even more useful if the sensor probes were included in the EVM kit. These probes make liquid probing a lot easier, removing the need for a special glass test vials or slides for testing.

A couple lessons learned from myself: I need a better method of investigating wet samples. You don't want to damage the module, so you need a safe and reliable way of getting a wet sample right up against sensing window without contaminating or damaging the unit. Most flasks and test tubes are not ideal, since they are curved and I noticed that this really messed up readings. The ideal scenario is to get an external probe so that you can in close without risking damage to the unit (just like they would be doing in industry). Alternatively for small batch tests of wet materials, some sort of flat glass container or a test slide could work. I guess you could even put the wet sample in plastic wrap, but I wouldn't trust that. Below is an example of my folly in scanning my red wine in a curved glass. Even if I get in close to the sample, there is so much light scattering occurring, which seems to generally lead to a very noisy signal output, and depression of the real peaks. My only guess is that this geometry is really affecting the path length of the beams, and that different amounts of transmission in the glass medium are really distorting results.

Summary

Strengths

• Unit works well once connected
• Connects easily to Bluetooth
• Quality Android App

Improvement Areas

• Clean up website with quick links to the latest install files
• Streamline install files, include all new firmware & software together
• Update GUI (CSV export of all absorbance, reflectance, intensity values)
• Include best practices for sample positioning (to improve user success with initial readings)
• Allow normalized absorbance values to be output (making for faster comparison of different scans)
• Identify major peaks in desktop GUI and mobile app, allowing users to quickly compare different scans