Polarization sensitive ultrafast mid-IR pump probe micro-spectrometer with diffraction limited spatial resolution.

A setup of ultrafast transient infrared IR spectrometer is described in this paper that employed Schwarzschild objectives to focus the probe beam to a diffraction limited spot. Thus measurements were performed with very high spatial resolution in the mid-IR spectral region. Furthermore, modulating the polarization of the probe light enabled detecting transient dichroism of the sample. These capabilities of the setup were applied to study transient absorption of Photosystem II core complex and to image an organized film of methylene blue chloride dye. Moreover, a study of noise sources in a pump probe measurement is presented. The predicted noise level of the current setup was 8.25 µOD in 10(4) acquisitions and compared very well with the experimental observation of 9.6 µOD.

Mobile spectroscopic system for trace gas detection using a tunable mid-IR laser.

We describe a mobile spectroscopic system for trace gas analysis based on the open path differential absorption spectrometer and the photoacoustic spectrometer. The first method allows long distance measurements (up to a few kilometers) while the second one provides local in situ detection of pollutants. The open path system is based on the nanosecond (f = 10 Hz, tau = 5 ns) lamp pumped Nd:YAG laser and a tunable two cascade optical parametric generator operating in the 5-12 microm spectral region. This source was mounted into the lidar setup based on the coaxial transmitter/receiver. The photoacoustic system was constructed using the same laser as well as a nonresonant photoacoustic cell.