W. Diehl’s research while affiliated with Battelle Memorial Institute and other places

A transportable laser system for remote sensing of road traffic emissions (carbon monoxide) has been developed and field testet at different sites in the city of Frankfurt. Based on the DAS technique using lead-salt diode lasers, the system yields mean values of the species density across a measurement path of several hundred meters. Interference with other absorbing species as well as varying operating conditions are compensated by using the second derivative technique. The time for starting operation after transportation of the system was two hours, time of availability during the campaign was better than 90%. It appeared sufficient to have technical checks and readjustments only once per day.

The design of CO2 laser transceiver system to establish and maintain a two way 1 Gbit/sec data link between two independently orbiting satellites is presented. The overall package has envelope dimensions of 70x35x90 cm, weighs 37 kg, and consumes 250 W of prime power. It comprises an externally modulated CO2 laser transmitter, an optical homodyne receiver, diffraction limited transceiving optics, a high performance pointing acquisition and tracking subsystem, and a stable light weight mechanical structure. Operational procedures are discussed and calculated performance data are given.

A laser absorption spectrometer for long path measurements of ambient carbon monoxide using second derivative techniques is described. First derivative techniques are used for automatic frequency stabilization of the diode laser. The linearity of system response for large laser frequency modulation was investigated experimentally and theoretically.