Larry B. Petway holds a Ph.D. in physics and has been working in the laser field for 25 years. His involvement with laser theory and application began while a graduate student. The title of his thesis was “Experimental and Theoretical Laser Fluorescence Studies of Excited States”.
He is presently the Assistant Branch Head of the Laser Remote Sensing branch at Langley Research Center, and leading the optical design, build, and demonstration of the Doppler LIDAR that is part of the ALHAT project. A number of innovative technological advancements have been developed to greatly improved the efficiency and signal to noise of the Doppler LIDAR during Dr. Petway’s time at NASA. The first generation Doppler LIDAR was built and successfully implemented for many years, but now the second generation design is completed, incorporating improvements in a more compact configuration.
He conducted research to develop an all solid-state terahertz laser that has multiple applications. Terahertz waves (30-micron to greater than 3 millimeter of the electromagnetic spectrum) have attracted a great deal of attention for their ability to penetrate solid surfaces and allow imaging of underlying materials. This technology, originally created for UV wavelength LIDAR technology, was adopted to measure the ozone from space.
Dr. Petway has led the development of a space-based UV laser transmitter to enable global earth observations of aerosols and ozone at resolutions greater than the current satellite instrument capabilities. As project lead of the UV effort, he was responsible for developing wavelength conversion technology to convert a Nd:YAG laser into an efficient, high-energy, tunable, pulsed UV laser in the 300-320 nm range, capable of space-based operations. A total of three nonlinear processing steps were need in this conversion technology, thus the risk was high. Three alternative technology development paths were initiated in parallel to obtain the UV wavelength objective. (1) A double pumped OPO experiment was designed with the aim of doubling the efficiency of the UV conversion. (2) The laser crystal Nd:Y2O3 development effort was pursued to replace the OPO to improve efficiency and reduce design complexity. (3) A UV conversion effort carried out by DOE’s Sandia National Labs.
Dr. Petway was also responsible for the building, testing and deployment of the Ti:Sap laser transmitter for the LIDAR Atmospheric Sensing Experiment (LASE). LASE is the first fully engineered, modular, tunable, autonomous Differential Absorption LIDAR (DIAL) system for the remote measurement of water vapor and aerosols across the troposphere.
During his course in development of solid-state lasers at NASA Langley, he has received several NASA awards for his contributions to the NASA remote sensing program:
* NASA’s Public Service Medal
* 5 NASA Superior Accomplishment Award
* 8 NASA Group Achievement Award
Contact Information:
NASA Langley Research Center
5 North Dryden Street
Building 1202, Room 237 C, MS 468
Hampton, VA 23681-2199
phone: (757) 864-8084
fax: (757) 864-8828
email: larry.b.petway@nasa.gov