In the last years, several techniques have been developed for the measurement of the three velocity components in a fluid plane or volume.Digital holography particle tracing velocimetry(DHPTV)was applied to observe the chain transformation process of magnetorheological fluids (MR fluids) under an external magnetic field. With the help of correlation coefficient(CC)method, the focus plane of standard particle target was determined. The displacement of standard target mounted on a precise displacement measurement workbench was compared with the distance measured by difference of focal planes movement. Making use of a controlled rotating platform with constant revolving speed, the rotation speed of particles was obtained after extracting the coordinates from reconstruction images. The measured speed was compared with actual speed of particles,which can be worked out through rotation speed of platform. The transformation speed was measured when magnetic particle moved along with magnetic direction under an external magnetic field. The experiments showed that a visible part of 3D velocity field could be observed in the chain transformation process of MR fluids with DHPTV.
A holographic display method combing the Amplitude of real picture and the phase of hologram is proposed to improve holographic display. The hologram of the onion epidermal cells was recorded in the in-line digital holographic system. Then the phase unwrapping method was used to get the real phase of the epidermal cells of the onion. Intensity distribution of onion is recorded in CCD illuminated by LED. Based on that, Burch and Kinoform coding are utilized to make CGH (computer-generated hologram) using phase and intensity obtained before. Experiments indicate that clear reconstruction image and desirable display result are achieved with this novel method, providing a new idea for development of CGH display.