Design Revision of Walters Probes—High Sensitivity Differential Temperature, CT2, Probes for Atmospheric Optical Turbulence Characterization

Abstract

As the Department of Defense (DoD) and industry continue to advance the development of high energy laser (HEL)–based directed energy weapon (DEW) systems, the need for modernized test and evaluation (T&E) and experimentation capabilities for DEW has become critical. This will allow airborne, ship-based, and land-based HEL systems to be tested against air and surface targets in a well-understood atmospheric environment. T&E capabilities in maritime test arenas and land environments will be enhanced by instrumenting open-air test ranges with advanced sensor systems, including atmospheric optical turbulence measurement systems, which play a critical role in HEL device beam and fire control. Teknicare, Inc. has conducted extensive reverse engineering of an existing differential temperature sensor previously used in data collection at various locations including Starfire Optical Range, Los Alamos National Laboratory, Nevada Test Site, Nellis Air Force Base, San Nicolas Island & Point Mugu NAWC on the PMSR as well as China Lake NAWC. This effort has included detailed requirements analysis as well as research of related designs, schematics, theses and reports conducted at Naval Postgraduate School by Dr. Donald L. Walters and his students. The devices, now known as Walters Probes, make use of precision fine wire thermocouples separated at a known distance to provide a measurement of temperature difference. The associated electronics provide necessary amplification and sampling rate to ensure a measurable ensemble average is obtained to determine CT2 at the Walters Probe location. These systems are capable of low noise operation and hence measurement of CT2 values that render atmospheric optical turbulence at extreme values indicative of terrestrial neutral events, therefore they can easily measure values expected in the near maritime environment. Revisions to the design to enhance reliability, sustainability, operability and maintainability have been undertaken to ensure the Walters Probes meet T&E mission OPTEMPO requirements.