Laser-based infrared sensor for fast and non-contact detection and identification of forensic traces in crime scene investigations

Traditional crime scene investigation is slow as traces are collected at the scene and only subsequently analyzed in the lab. Rapid contactless detection and examination of various trace materials at the crime scene without any alteration avoids degradation of traces, significantly speeds up investigation and reduces the time to capture the originator before he can commit further offences. Furthermore, contactless identification is crucial in guaranteeing the health and safety of crime scene investigators for chemical, biological and explosives treats. Here we report on the development of a quantum-cascade laser based infrared sensors, that allows instantaneous detection and identification of a wide range of forensic relevant samples, from explosives to drugs, their precursors, but also biological traces such as blood. The system is based on MOEMS-EC-QCLs that allow kilohertz spectral scan speed. Two such sources are combined in the sensor to extend the spectral coverage to increase the selectivity without sacrificing scan speed. We report on the system design and show first results on drugs and explosive identification.