深度和波长补偿算法生成彩色计算全息图

Color Computer Holography Generated by Depth and Wavelength Compensating Algorithm

针对新查表法(N-LUT)在计算彩色三维场景全息图时,查找表占用的存储空间大且计算速度较慢的问题,提出了深度和波长补偿N-LUT算法(DWC-N-LUT)快速生成彩色三维场景的全息图。将组成三维场景的点云分割为具有特定深度的一系列二维图像,并由提前存储的深度补偿因子计算某一深度二维图像红色(R)通道的基元条纹图(PFP),通过平移此PFP获取物光点R通道在全息面上的复振幅分布。利用波长补偿因子直接得到物光点绿色(G)通道和蓝色(B)通道的复振幅分布。用飞机模型和汽车模型进行的数字模拟实验表明:DWC-N-LUT法能够准确表现彩色三维场景的颜色和深度信息;物光点的复振幅引入随机相位可以有效降低再现像的相干噪声;DWC-N-LUT法与N-LUT法相比,查找表的存储空间减小了10倍以上,计算速度提高了约22%。

To solve the problem that the memory space is large and the calculation speed is slow in the novel look up table （N-LUT） method when calculating the color hologram three-dimensional scene. The depth and wavelength compensating N-LUT method （DWC-N-LUT） is proposed to generating color hologram three-dimensional scene fast. The point cloud, which compose three-dimensional scene, are sliced as a series of two-dimensional images with defined depth. The principle fringe pattern （PFP）for red （R） channel corresponding to one depth is obtained according to the pre-stored depth compensating factors. The complex amplitude of object point for R channel is acquired by shifting the PFP. The complex amplitude of object point for G and B channel is directly generated through multiplying that for R channel by wavelength compensating factors. Numerical simulation experiments with an airplane model and a car model indicate that the color and depth of three-dimensional scene can be precisely provided with DWC-N LUT method. The coherent noise in the reconstruction images can be obviously eliminated by adding random phase to the complex amplitude of object point. The memory space of DWC-N-LUT method is 10 times less than that of N-LUT method, and the computational speed of the proposed method is approximately improved 22 % comparing with N-LUT method.