Supercontinuum lidar applications for measurements of atmospheric constituents

Recent advances in the field of supercontinuum lasers have provided a unique opportunity for developing lidar instruments that cover a wide spectral range. These instruments permit many simultaneous measurements of differential absorption spectra (DIAL and DAS techniques) to determine species density. Application of MODTRAN^TM 5 and other simulation software has allowed us to design and validate the findings of supercontinuum lidar systems developed at Penn State Lidar Laboratory. The multiple line differential absorption concepts have been demonstrated with various system topologies for a host of atmospheric windows in the visible to near infrared regions. During the past three years, we have developed and demonstrated several systems that are capable of measuring concentrations of various atmospheric constituents at background or elevated levels through long path absorption by transmitting only milliwatts of optical power. Our most recent supercontinuum lidar system utilizes a nanosecond supercontinuum laser fiber optically coupled to a transceiver system for remote sensing of atmospheric species concentrations. Due to the flexibility of the design, the operational prototype is currently being used to demonstrate the capability for accurately measuring real world open path atmospheric concentrations across the Penn State campus. The purpose of this study is to develop the technology and to demonstrate the capability for accurately measuring species concentrations without the complexities and uncertainties inherent in hyper-spectral remote sensing using the sun as a source, or the limitations and errors associated with using pairs of laser lines for DIAL measurements of each species. Initial simulations and measurements using this approach are presented.