Electron Multiplying CCD a New Sensor for the Wales LIDAR Application

Abstract

The Earth Explorers Core Mission WALES (Water vApor Lidar Experiment in Space) is aimed at providing a better understanding of the distribution of atmospheric water vapor in the troposphere and lowermost stratosphere on a global scale using a space-based Differential Absorption Lidar (DIAL) observation technique. The Lidar system contains Laser and Detectors. Optical detectors for earlier LIDAR space missions have been built with Avalanche Photo Diodes (APDs) based detectors which have several drawbacks for such applications, e.g. saturation problems with ground echo (possible destruction), relative complex electronics, etc. As a new sensor type for such application has been recognized the Electron Multiplying Charge Coupled Device (EMCCD) of the company E2V. With this EMCCD it is possible to detect from single photon to thousands and benefit from ranging capabilities down to 100 m. The device contains an electron multiplication register (provides gain) which multiplies the electrons before they pass the output amplifier. To evaluate such a sensor for the WALES mission an ESA detector study and test campaign within the ESA ALCATEL SPACE leaded WALES Phase A study was conducted under ESA contract. This paper will demonstrate the EMCCD sensor and its promising application for the WALES mission gained from a test campaign of such sensors in 2003 and will compare this new sensor with the conventional APD solution.