Sensor - AS7265x Specifications and Usage

Hey everyone!

I’m working on a project where we’re looking to detect allergenic particles in semi-industrial kitchens, and I’m considering using the Triad Spectroscopy Sensor - AS7265x from SparkFun. I’ve got a few questions, and I’m hoping someone here might have some experience or insight:

  1. Using the Sensor at a Distance: Is it possible to use this sensor without having it in direct contact with the sample? If so, what’s a good distance for it to still give accurate readings? And, any ideas on how to get it to work well at distances like 10 to 30 cm from the object?
  2. Fiber Optics: Would it be possible to use fiber optics to carry the light to the sensor while keeping good accuracy? If anyone’s tried this, I’d love to hear how it went!
  3. Precision: Speaking of accuracy—how precise is this sensor in terms of percentage when used under ideal conditions?

Any help or suggestions would be awesome! Thanks in advance for your insights!

If you mean the triad spectroscopy sensor, it measures light through three different sensor openings, with six wavelength bands for each of the three sensor ICs, so it is not a good choice for fiber optics. Nor is there a good way to interface a fiber optic cable to any of the individual openings, although it might be possible to glue an SMA fiber optic adapter to one.

Any stray light (that is, not from the sample) will contaminate the measurements.

The data sheet has the specs for the accuracy of the individual wavelength band intensity measurements.

More broadly, how do you imagine that spectroscopic measurements could be used to detect allergenic particles?

  1. You do not want it to contact the sample…you want the sensor to be at a steady known fairly close distance, though…I used mine at about 10 cm for this GitHub - TurnerRussell50/Project-Sneaky-Peanut-Butter and it worked. It could be used farther, but everything becomes way more noisy

  2. See above

  3. Eh, it was 100% accurate for my small project lol. It really depends on how tightly you’ve controlled for the known variables (subtract background light signal, etc). Accuracy figures are on page 8, 13 and many more here

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Thanks for the response!

I understand that the Triad Spectroscopy Sensor isn’t ideal for use with fiber optics due to the limitations with the three sensors and the openings for the wavelength bands. That definitely helps me avoid pursuing an impractical solution.

As for your question about how spectroscopic measurements could be used to detect allergenic particles, the idea is to identify specific characteristics of ingredients or contaminants at the molecular level. By analyzing the spectral signatures in the VIS-NIR bands, we aim to detect the presence of certain compounds, like gluten, that are associated with allergens. We know this can be challenging, but spectroscopy has the potential to be a non-invasive and relatively fast tool for this type of monitoring.

Thanks again for the insights and clarifications!

I have a couple more questions regarding the setup and sensor capabilities:

  1. Do you think it would be necessary to add more VIS or NIR lights to improve detection accuracy for this type of project? Or is the built-in illumination sufficient?
  2. Regarding the field of view (FOV) and the measurement range: The data sheet mentions some specs on FOV, but I’m wondering how that applies in a practical scenario. For example, if I’m scanning a 20 cm diameter plate of food, would the sensor be able to analyze that entire area in one pass? Or is there a limit in terms of how much area it can cover at a time?
  3. Lastly, to increase the detection diameter, would it be feasible to add a collimation lens? If so, what would be the best approach to implement that?

Thanks again for your insights!

The AS7265x sensor accepts incoming light in a cone of solid angle about 40 degrees. The sensitivity drops to zero at the edges, and if you wish to take that into account, a cosine function may be a useful model for the sensitivity as a function of angle.

Therefore to obtain the spectrum of the light coming from a 20 cm diameter plate of food, place the sensor at distance d = 10 (cm)/tan(20 degrees) = 27 cm.

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Usually the built-in LEDs are more than enough

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