Multiplexed Mid-Infrared Imaging of Trace Explosives

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Project Description

MIR light, that is light with a wavelength in the range of 4 to 12 μm, is useful for identify the presence of extremely small quantities of explosives. When a specific explosive is present, it will absorb light at very specific wavelengths that can be used as a unique “fingerprint.” ALERT projects, led by Prof. Samuel P. Hernandez-Rivera (University of Puerto Rico) and Prof. Anthony Hoffman (University of Notre Dame), and ALERT industrial partner EOS Photonics are using mid-infrared light to identify molecular fingerprints corresponding to trace amounts of explosives. The ability to detect explosives with MIR light is limited by the availability of high-performance MIR laser sources and imaging platforms. MIR lasers, especially lasers that can identify many unique explosives simultaneously, are very expensive. Additionally, imaging platforms are difficult to produce since few MIR “cameras” exist (or are very expensive).

This project develops technology that will make it cheaper to produce laser systems that can identify multiple explosives at the same time, as well as a complementary imaging platform that will use the laser to “see” the residues. One of the easiest and simplest ways to see the residues is to use two lasers at the same time: one to be absorbed by the explosive and one to essentially illuminate the background. The ratio of the brightness of the two lasers can then give you information on the presence of explosives. To make sure the system is working properly, the two lasers should follow the same beam. MIR lasers, typically, are made on semiconductor chips in such a way that it is difficult (or expensive) to combine them together in one beam. The first part of this project is to use new micro-fabrication techniques to build a system which combines the light out of two expensive lasers together in an inexpensive silicon based chip. The light can then be used for imaging or possibly for detection of explosives in small quantitates of liquids, on the chip. Once laser light is combined, we will build imaging systems which do not need cameras, by using techniques our group developed for medical imaging without cameras. Such MIR explosive imaging technology is not currently available, and potentially could lead to even more advanced screening and detection systems.

Project Leader
  • Scott Howard
    Assistant Professor
    University of Notre Dame

Students Currently Involved in Project
  • Tahsin Ahmed
    University of Notre Dame
  • Genevieve Vigil
    University of Notre Dame