Performance of a breadboard lidar receiver at 1570 nm for remotely sensing atmospheric CO/sub 2/ concentration

Summary form only given. We are developing a differential absorption lidar technique to remotely measure the atmosphere CO/sub 2/ concentration from aircraft. It uses two alternating multi-kilohertz pulsed lasers, one "on-line" at a CO/sub 2/ absorption wavelength about 1570 nm and one "off-line" at a nearby wavelength. The two lasers are co-aligned and pointed at the ground. The receiver detects the ground echoes from both lasers and measure the ratio of the echo pulses energies to determine the absorption due to the CO/sub 2/ in the column along the optical path. The goal is to achieve a signal to noise ratio (SNR) of 500 to 1000 in each measurement after averaging over a few tens of seconds for detecting CO/sub 2/ concentration to a few parts per million.