Sub-second infrared broadband-laser single-shot phase-amplitude polarimetry of thin films

We report on the first, to the best of our knowledge, sub-second, sub-mm(2) infrared (IR) spectroscopic measurements of thin organic films employing a laser-based phase- amplitude polarimeter in reflection geometry. The polarimeter uses a broadband mid-IR quantum cascade laser tunable between 1318 cm(-1) and 1765 cm(-1), as well as a single-shot beam division scheme for simultaneous single-pulse phase and amplitude measurements. The instrument achieves 120 mu m spatial and <0.5 cm(-1) spectral resolution, while providing unrivaled performance in terms of acquisition times. Spectral measurements within 100 ms and single-wavelength tracking at 16 mu s are now possible. Investigating the vibrational properties accessible in the mid-IR, the polarimeter was applied for monitoring changes in molecular interactions of a 150 nm thin myristic acid film during its thermal phase transition around 55 degrees C. (C) 2019 Optical Society of America