High energy laser detection through thermoelectric generators (Conference Presentation)

Detection of high energy laser strikes is key to the survivability of military assets in future warfare. The introduction of laser weapon systems demands the capability to quickly detect these strikes without disrupting the stealth capability of military craft with active sensing technologies. This paper explores the use of thermoelectric generators (TEGs) as selfpowered passive sensors to detect such strikes. Experiments were conducted using lasers of various power ratings, wavelengths, and beam sizes to strike 2cm x 2cm commercially available TEGs arranged in different configurations. Open circuit voltage and short circuit current responses of TEGs struck with 808nm, 1070nm, and 1980nm lasers at irradiance levels between 8.5-509.3W/cm2 and spot sizes between 2-8mm are compared. TEG surface temperatures indicate that the sensor can survive temperatures nearing 400°C. TEG open circuit voltage magnitudes correlate more strongly with net incident laser power than with specific irradiance levels, and linearity is limited by Seebeck coefficient variation with temperature. Open circuit voltage responses are characterized by 10%-90% rise times of ~2-10s, despite surface temperatures not reaching equilibrium. With open circuit voltage as the sensing parameter, detection thresholds three times the above the standard deviation noise level can be exceeded within 300ms of the start of a laser strike with irradiance levels of ~200W/cm2. Potential harvested power levels as high as 16mW are estimated based on measured electrical responses. A multi-physics finite element model corresponding to the experiments was developed to further optimization of a lightweight, low-profile TEG sensor for detection of high energy laser strikes.