紧凑型矢量光场发生器中4f系统的对齐方法

Alignment of 4f system in compact vector optical field generator

提出了紧凑型矢量光场发生器中4f系统在横向和纵向上的精确对齐方法,并进行了实验验证。将设计的特定相位图加载到矢量光场发生器中,通过调整4f系统中各元件之间的距离以及物面和像面到相应透镜的距离,以CCD采集光斑图像的锐利程度作为判据来实现4f系统的纵向对齐。以空间光调制器的相位控制区域作为参考坐标系,采用四象限图测量另外三个调制区域的光斑在横向上的坐标位移,通过在设计的相位图中预补偿测量到的坐标位移来实现4f系统的横向对齐。实验结果表明,所提出的4f系统对齐方法可以显著减小矢量光场发生器中所调制光斑的衍射效应。

Precise transverse and longitudinal alignment methods were experimentally demonstrated for the 4f system in compact vector optical field generator(VOF-Gen).Specifically phase patterns are designed for the VOF-Gen,and the longitudinal alignment is achieved by adjusting the distance between the components in the 4f system as well as the distance between the object plane(image plane)and its corresponding lens,with the sharpness of the image captured by the CCD as the criterion.The Cartesian coordinate was used in the phase modulation region of the liquid crystal spatial light modulator as reference.Specifically,four-quadrant phase patterns are employed to measure the transverse displacements between the modulated beam in the other three regions and that in the phase modulation region.The transverse alignment can be realized through pre-compensating the obtained transverse displacements in the designed phase patterns.The experimental results show that the presented alignment method could notably minimizing the diffraction effects of the modulated beam output from the VOF-Gen.