FAST WAVELENGTH SWITCHING OF NARROW-BAND EXCIMER LASERS

A novel system was developed, which allows one to switch the wavelengt h of a narrow-band excimer laser between two successive light pulses a t a repetition rate of at least 250 Hz. This is realized by a periodic ally driven piezo actuator, which is attached to the diffraction grati ng of the narrow-band KrF excimer laser. The achieved position accurac y of the grating leads to a wavelength reproducibility of +/- 0.2 pm, which allows one to apply this system to laser spectroscopic investiga tions like LIF or LIPF of OH in flames. Using the fast wavelength swit ching system background reduced concentration and temperature fields i n flames can be measured within one sequence. Some possible realized a nd planned applications like the measurement of gas temperature, the d iagnostic of turbulent combustion processes, and the investigation of combustion processes under microgravity are discussed. (C) 1997 Americ an Institute of Physics.