We describe all solid state differential absorption lidar (DIAL) based on the mid-infrared (IR) tunable Optical
Parametric Oscillator (OPO). Generation of tunable mid-infrared laser radiation using a two stage tandem OPO was
demonstrated. The first stage was based on the nonlinear KTP crystal and produced up to 45 mJ of 1.57 μm radiation,
while pumped by a commercial Q-switched Nd:YAG laser. The quality of signal beam was improved by the use of
unstable resonator. The AgGaSe2 crystal was used in the second stage OPO. Idler energies up to 1 mJ were generated at
this stage within tuning range from 6 to 12 μm. The receiver consisted of a 250 mm gold mirror telescope, two channel
detection system and control electronics. We have designed a photoacoustic cell for wavelength calibration of lidar.
Preliminary lidar field test results are presented.
A simple device, Frequency Tracer (FT), for ultrashort light pulse duration and chirp simultaneous measurement is introduced. FT operation is based on the second-harmonic autocorrelator beam two-dimensional image analysis (time versus frequency), and it is able to evaluate the temporal phase variation over femtosecond pulse duration. The spectral information of fs pulse in FT originates from the angular divergence of a second-harmonic signal beam, and there is no need in using the spectral apparatus. Femtosecond pulses duration and chirp measurements of the Ti:sapphire laser system multipass amplifier (MPA) during adjustment of compressor pair of gratings were done.
We present the second phase of our work in project LISATNAS devoted to design the differential absorption lidar (DIAL) based on the mid-infrared (IR) tunable Optical Parametric Oscillator (OPO). Generation of tunable mid-infrared laser radiation using a two stage tandem OPO was demonstrated. The first stage was based on the nonlinear KTP crystal and produced up to 45 mJ of 1.57 μm radiation, while pumped by a commercial Q-switched Nd:YAG laser. The quality of signal beam was improved by the use of unstable resonator. The AgGaSe2 crystal was used in the second stage OPO. Idler energies up to 1.2 mJ were generated in this stage within tuning range from 6 to 12 μm. The receiver consisted of a 250 mm gold mirror telescope, pyroelectric detector with control electronics. Preliminary field test results for detection of H2O using a retroreflector are presented.
We describe a new development of differential absorption DIAL spectrometric system based on the mid-infrared tunable Optical Parametric Oscillator (OPO), pumped by compact Q-switched lasers. Mobile LIDAR was assembled in the truck and is devoted for selective pollutant analysis in the distance range extending from hundred
of meters to a few kilometers. A reliable cascade mid-IR generation scheme was developed. Pulse energies up to milijoule in mid-IR (λ=8-12 μm) have been already obtained using nonlinear AgGaSe2 crystal. The collinear optical scheme with 25cm (10inch) gold mirror telescope, MCT thermoelectrically cooled detector with control electronics was tested at 250m optical length and currently is under further development.
We describe a new project (acronym LISATNAS) approved by the Lithuanian Research Council in 2003 devoted to the development of differential absorption lidar (DIAL) and stationary spectrometric systems based on the mid-infrared tunable Optical Parametric Oscillator (OPO), pumped by compact Q-switched lasers. The purpose of the project is to construct a mobile infrared lidar, assembled in the truck for selective pollutant analysis - possessing spatial resolution of a few meters in the distance range extending from hundred of meters to a few kilometers. A reliable cascade mid-IR generation scheme was developed. Pulse energies up to milijoule in mid-IR have been already obtained using nonlinear AgGaSe2 crystal. Optoacoustic and multipass cells were constructed for stationary spectrometers. Preliminary results with detection of CO2, CH4, H2O and other gases in the ppm concentration range show good sensitivity. Special pollutants were synthesized by chemical group of the project for spectrometric experiments: multiatomic nitrocompounds, such as trinitrotoluen (TNT) or trotyl, DNT (dinitrotoluoen), MNT (mononitrotoluoen) and RDX (heksahydro-1.3.5-triazyn). The mobile DIAL system based on the tunable laser in the 8-12 μm region, 10" goldmirror telescope, MCT cooled detector with control electronics is under construction and should be finished in 2005.
We have designed and manufactured a simple device, named frequency tracer, (FT) for fs pulse temporal phase measurements. FT is able to present a determination of the instantaneous frequency dependence on time fs pulse together with an accurate data sufficient for a complete characterization of light field. The main feature of our designed FT device is the simplicity: no spectral apparatus is needed and fs pulse phase distortion determination does not require complicated iterative mathematical algorithms. Using a single-shot real-time implementation of this technique the multi-pass amplifier (MPA) compressor of fs Ti:sapphire laser system was adjusted.
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