Abstract
This paper presents a digital holographic technique for particle measurement in depth direction by using two-wavelength reconstruction and the measurement accuracy is evaluated by numerical simulation. In present method, image reconstruction is numerically carried out with two different wavelengths to shift particle image along depth direction and particle position in depth is computed by using the shift amount of particle image. The performance test of the present method is numerically evaluated by using the model of a single particle of 10, 20, 30, 40 μm in diameter and 1, 5, 10mm in depth. It is shown that the measurement error of the present method is -2.8 -2.6 μm for a particle of 20 |j,m in diameter and depth range from 1mm to 10mm, hence the measurement accuracy is found to be better than that of conventional method.
