圆柱型层析计算全息技术研究

Study on tomographic computer generated cylindrical holography

研究了三维物体圆柱型层析计算全息技术:分别将不同深度三维物体的圆柱截面与对应的点扩展函数进行卷积后叠加获得位于全息面的物光场分布,并与参考光干涉获得计算全息图,再现该全息图可对原物体实现360°观测。首先建立三维物体圆柱型层析计算全息模型,推导系统点扩展函数与不同方向采样间隔所需满足的条件;然后通过理论与实验分析了物体不同圆柱截面半径、波长对空间频率和系统传递函数的影响,采用峰值信噪比和均方误差来评价再现图质量;最后对三维地球模型采用圆柱型层析计算全息编码,再现了不同观察角度与深度的信息。仿真结果表明,该方法对于一般三维物体360°全视场显示具有较高的应用价值。

The method for tomographic computer generated cylindrical holography of three-dimensional object was researched:the diffracted wavefront on the holographic surface was the superposition of convolution between the cylindrical cross sections of three-dimensional object with different depths and the corresponding point spread functions,and the computer generated hologram could be obtained by recording the interference patterns from the diffracted object wavefront and the reference.The 360°view of the object could be observed from the reconstructed holograms.Firstly,the tomographic computer generated cylindrical holography model of three-dimensional object was built,and the conditions of system point spread function and sampling interval in different directions were derived.Secondly,the impact on the spatial frequency and the system transfer function by the radii and the wavelengths of different cylindrical cross sections was analyzed from both theory and experiments,and the peak signal to noise ratio as well as the mean square error were adopted to evaluate the quality of the reconstructed holograms.Finally,the tomographic computer generated cylindrical holography was used to encode the three-dimensional earth model,which represented the information of different observation angles and depths.The simulation results show that the proposed method has wide applications for 360°full field display of the ordinary three-dimensional objects.