Advantages of UV Lasers in Laser and Phase Doppler Anemometers for Submicrometer Particles
For laser Doppler (LDA) and phase Doppler anemometry (PDA) measurements with submicrometer particles ultraviolet lasers with wavelengths between 240nm and 280nm are compared with lasers emitting visible radiation. UV lasers offer a main advantage in the higher signal-to-noise ratio (SNR) obtainable, since the scattered power is significantly increased at shorter wavelengths. Furthermore, for PDA the capability of making size class distinctions in the submicrometer size range is improved, as shorter wavelengths lead to steeper phase difference-to-diameter relationships. In particular, the use of ultraviolet (UV) laser light enables the size class distinction of 0.2µm from even smaller particles, that is not possible when using visible radiation. The feasibility of performing laser Doppler and phase Doppler anemometry measurements with ultraviolet laser light is confirmed by experiments.
Unable to display preview. Download preview PDF.
- Bohren, C. and Huffman, D. Absorption and Scattering of Light by Small Particles. John Wiley & Sons, Inc, 1983.Google Scholar
- Domnick, J., Ertel, H., and Tropea, C. Processing of phase-Doppler signals using the cross spectral density function. In Proc. 4th Int. Symp. on Applications of Laser Anemometry to Fluid Mechanics, page 3–8, Lisbon, 1988.Google Scholar
- Durst, F., Meiling, A., and Volkholz, P. The extension of phase-Doppler anemometry to small particles. In Proc. 4th Int. Congress on Optical Particle Sizing, page 185, Nürnberg, 1995.Google Scholar