Detecting illicit trace material

Thomas Hof

The question of ‘how’ has been asked numerous times by various people who were visiting us over the years. I myself have answered this question more times than I can remember. The nice thing about the technology we are working on is that we have a relatively simple answer to a very complex problem.

Detecting illicit trace material

It took me a while of closely working with members of the original team at the University of Florida (UF) to really understand the physics behind the Delta R technology, and the final ‘aha’ only came when we were visited by the inventor of the technology, Dr. Hummel, and he explained it to me in his words.

 

The name Delta R already gives some of the idea away; we look at the difference (Delta) of the reflection (R) of a surface. For years we, and I’m sure also the team at UF, have used a cartoon like the one seen below to explain the technology.

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The principle of Delta R technology

First, we need to send light towards a surface of which we want to capture the reflection. For this, we use a high-end light source that is incredibly stable because we need to make sure that any differences, we capture do not come from hardware fluctuations. We use a set of optics to manipulate the light into a line, convenient for scanning wide surfaces.

 

What happens on the surface is that whatever is on there will absorb part of the light and reflect everything it does not absorb. This absorption tells us something about the substance, as it creates an absorption feature which we can use for identification.

 

The reflection is captured by our spectrometer, specifically designed for our application. Its function is to separate the information (different wavelengths, can also be seen as different colours) from the reflected surface onto the pixels of our camera. This information is then used by our software to calculate the difference between the image coming in and the image before that and running our algorithms on that information will result in a classification. Calculating the difference between two images means that we only see the difference in absorption between two parts of a surface. This gives us a single clear feature for a substance, while negative effects of backgrounds are minimized.

Delta R Shoe Scanner

Delta R Shoe Scanner

Delta R Shoe Scannerhttps://www.sg11.nl/products/delta-r-shoe-scanner/

This in principle is how the Delta R technology works. It has proven itself to be capable of detecting very small amounts of substances. So small in fact, that we must think about methods to reliably make samples of amounts that are no longer visible with the naked eye.

 

Working on this technology means working with a large variety of expertise, from programming to chemistry, never having a dull moment and always having to keep learning to improve our product.

Thomas Hof

Questions about this insight? Contact Thomas Hof

+31 (0) 88 250 16 00 / insight@sg11.nl