Effects of air ionization on particle holographic image

In particle field holography, an optical system named 4F system is usually used for imaging particles in an appropriate position. At the real focus of the 4F system, air will be ionized when the laser pulse energy increases. In this case, intensity distribution of reconstructed images of off-line and in-line holography are opposite to those obtained under normal conditions. The reason is the spatial filtering. effect caused by the air ionization. Furthermore, high quality off-line particle holographic images can be obtained with air ionized, by adjusting the exposure pulse intensity.