Progress toward handheld THz spectroscopy and THz Air Photonics

Development and application of real-time (> 5Hz) first-surface and bulk reflection measurements using the mini-Z THz time-domain-spectrometer (TDS) are presented for standoff detection and identification of organic, pharmaceutical and energetic compounds. A non-iterative baseline correction for scattering is applied to real-time data to expand THz sensing across a wider range of sample preparation techniques, including pressed pellets, powders and other irregular surface geometries. Performance is assessed using selected samples of organic, pharmaceutical and energetic compounds with absorption peak positions in the 0.1-3.5 THz range, with results >99% confidence without the use of HDPE sample references using standard correlation and partial-least-squares (PLS) techniques. The current state of THz Air Photonics, where selected gases are used as both THz emitter and detector, and how it relates to real-time identification will also be presented.