INFLUENCE OF THE MEASUREMENT VOLUME ON THE PHASE ERROR IN PHASE DOPPLER ANEMOMETRY .2. ANALYSIS BY EXTENSION OF GEOMETRICAL-OPTICS TO THE LASER-BEAM REFRACTIVE MODE-OPERATION

The influence of the measurement volume can be investigated by using e xtended geometrical optics, which is based on geometrical optics by in cluding the amplitude and phase distribution in the laser beam. The dy namics in phase Doppler anemometry can be analysed, in addition to eff ects of the particle size-dependent detection volume. Extended geometr ical optics has been developed as a powerful tool to investigate these influences for each order of light scattering separately. Phase error s caused by Gaussian-beam intensity distribution and the curvature of the wave fronts beyond the beam waist can easily be calculated. Accord ing to Part 1 (Reflective Mode Operation), the influence of the partic le trajectories on measured phase and mass concentration is simulated for refractive mode operation.