LED-based lidar quantifies dust devils on Mars
A rugged, miniaturized, LED-based lidar system designed to study Martian dust devils has been developed.
A rugged, miniaturized (10 cm3), LED-based lidar system designed to study Martian dust devils has been developed by researchers at Chiba University, Chiba Institute of Technology (Narashino), Fukuoka University, Okoyama University, and the Meteorological Research Institute (Tsukuba). Although dust devil size and motion can be estimated from camera images, lidar can yield more-accurate information such as the diffusion and convention characteristics of dust and other particles in the wind flow.
Because laser-based lidar systems are too large and consume too much power, the LED source is a logical alternative, especially because the Nichia (Anan, Japan) 385 nm LED source chosen has been used on other spacecraft missions and can achieve 0.75 W pulsed power (7.5 nJ/10 ns) at a pulse-repetition frequency of 500 kHz. A specially designed high-speed photon counter from Trimatiz (Chiba, Japan) is synchronized to the high repetition frequency of the LED source and measures the photons that enter the 3 mrad Cassegrain telescope receiver optics over a series of bins to achieve a spatial resolution of 0.15 m for a 1 ns bin width and operates for pulse repetition rates up to 1 MHz. Wind-tunnel experiments using the LED-based lidar system successfully recorded the diffusion and convection characteristics of glycerin smoke in 0–5 m/s winds 15 m ahead of the instrument. In the next round of experiments, the researchers will simulate the lighting conditions as they would be on planet Mars to ensure that their system will operate successfully in a Martian atmosphere. Reference: T. Shiina et al., "LED-powered mini-lidar for martian atmospheric dust studies," SPIE Newsroom (Oct. 28, 2016); http://dx.doi.org/10.1117/2.1201609.006707.