部分相干光数字全息消色差相移技术研究

为了在以发光二极管作为光源的数字全息中降低系统相移误差,引入消色差相移的方法。对所提的方法进行了理论分析和实验验证。研究了发光二极管的光谱分布,并计算了在其光谱范围内使用压电陶瓷微位移器引入的相移误差,分析了基于旋转半波片的消色差相移装置的原理,计算出半波片位于不同方位角时两干涉光束间的相位差,由计算结果可知,此相位差独立于波长,即可以实现消色差相移。最后采用普通商用发光二极管作为光源,分别使用不同的相移方式进行了相移数字全息实验。结果表明,采用消色差相移装置的数字全息重建结果质量较采用压电陶瓷相移器的重建结果质量有明显提升。这一结果对于提升部分相干光数字全息的重建质量是有帮助的。

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.