Mobile CARS instrument for combustion and plasma diagnostics

A mobile CARS system for combustion and plasma diagnostics is described. The instrument is compact, easily transportable, readily adaptable to a wide variety of laboratories and experiments, capable of withstanding high noise and vibration levels, and remotely operable to protect the operator and delicate components from high noise or hazardous environments. The system is intended for single-pulse temperature and concentration measurements in practical combustion systems, such as gas turbines and diesel engines and plasma process applications. The instrument consists of three major subsystems, each of which is easily transportable. The transmitter consists of a modified, commercially available, 20 Hz Nd:YAG laser, self-constructed dye lasers, and appropriate optics to produce the CARS pump and Stokes beams in the properly phase-matched orientation and direct them to the measured point. The transmitter consists of two optical pallets on a 2 1/2- x 5-ft cart and is connected by a single umbilical to the laser power supply. The receiver subsystem is a smaller optical pallet (2 x 2 ft), which collects the Stokes, pump, and CARS beams, separates them, and focuses the CARS beam into an optical fiber for transmission to a remotely located spectrograph. The receiver also contains two photomultiplier tubes, one to monitor alignment of the transmitter and the other, used in conjunction with a reference cell and the residual Stokes and pump beams, to determine gas concentrations