Particle size, displacement, and velocity measurements with pulsed-laser holography

摘要

A method for measuring the size, position, displacement and velocity of particles in a particle field with pulsed-laserholography is introduced. In-line holography and off-axis holography are applied to analysis of particle fields, especially off-axis holography. A 4-F optical system is used in the holographic recording system, in which the information on particles is recorded on a holographic plate. In a parallel optical field, the particle analysis can be performed with different instruments and in different depth of field. The parallel optical field imparts each particle with the same amplification ratio. This kind of optical system will favour the reconstruction, data processing, and calibration of particles in a particle field. An interference pattern of particles formed on a recording plate and relationship among diameters of the particles, far-field number, and the distance from the plate to a particle are analyzed. Some experimental results of the size, position, displacement, and velocity measurement of particles of a reconstructed particle field are presented. The particle identification and the formation of noise in an image of a reconstructed particle field in one section are also discussed.