In recent years, a large number of linear and nonlinear laser-based diagnostic techniques for nonintrusive measurements of species concentrations, temperatures, and gas velocities in a wide pressure and temperature range with high temporal and spatial resolution were developed and have become extremely valuable tools to study many aspects of combustion. Modern "pump-probe" laser spectroscopic methods give direct insight into the microscopic dynamics, product channel distributions, and reaction

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... ates of elementary combustion reactions over a wide range of temperatures and pressures. Nonlinear laser spectroscopic techniques using infrared-visible sum-frequency generation can now bridge the pressure and materials gap to provide kinetic data for catalytic combustion. Laminar flames are ideal objects to develop the application of laser spectroscopic methods for practical combustion systems and to test and improve gas-phase reaction mechanism in combustion models. Besides diagnostics, lasers can also provide welldefined starting conditions for detailed experimental and theoretical studies of ignition processes. Nonintrusive laser point and field measurements, especially joint velocity-scalar data at the same point in space and time, are of basic importance in the validation and further development of turbulent combustion models. As an area for the application of quanitative laser spectroscopy to practical combustion devices, investigations in internal combustion engines are described. Finally, the potential of laser techniques for active combustion control in various devices from laboratory burners to full-scale jet engines, municipal waste incinerators, and pressurized fluidized-bed reactors are illustrated.