A New LIDAR Method using MEMS Micromirror Array for the JEM-EUSO mission

LIDAR (LIght Detection And Ranging) is an important method in measuring atmospheric transparency that is used to correct fluorescence light yield from extensive air showers. For the JEM-EUSO (Extreme Universe Space Observatory on Japanese Experimental Module) mission to observe ultra-high cosmic rays at the ISS (International Space Station) orbiting at 400 km altitude the method is used also to measure the cloud-top altitude which is one of crucial information to estimate the energy of primary cosmic rays. A novel type of space-LIDAR system has been proposed for JEM-EUSO telescope. This system utilizes an array of rapid MEMS (Micro-ElectroMechanical Systems) micromirrors that allow shooting the source laser light in any direction in the view of the telescope. The detection of backscattered photons is made with the JEM-EUSO telescope. The key element of the rotatable micromirrors is the electrostatic analog two-axes actuators with resonance frequencies of about 1 kHz. The micromirror plates installed on top of the actuators are designed to have high-quality surface roughness (lower than 4 nm in average) and robustness in a long-term exposure to the LIDAR beam. A prototype of the micromirror array was successfully tested on the ISS. The LIDAR concept, system design, and initial test results are presented.