Research of achromatic phase shift by means of partial coherent digital holography

In order to decrease system phase-shifting errors in light emitting diode based digital holography,achromatic phase shift was introduced.Both theoretical analysis and experimental results were displayed.First of all,the spectral distribution of the light emitting diode was studied and the phase shift error induced by micro-displacement pizeo-electric ceramic actuator was calculated.Then the principle of an achromatic phase-shifter based on a rotatable half wave-plate was studied and it was found that the phase difference between the two beams was,in principle,independent of wavelength.Digital holography by means of micro-displacement pizeo-electric ceramic actuators and achromatic phase-shifters was carried out respectively and the quality of the reconstructed fields was compared.The experimental results indicate that the reconstruction quality by means of achromatic phase-shift was greatly improved compared with that by means of microdisplacement pizeo-electric ceramic actuators.The results are helpful for the reconstruction quality of partial coherent source based digital holography.