以传统的干涉法全息技术为基础, 本文提出了一种纯光学的三维显示全息技术。利用空间光调制器实现真实物体的物光波前重现, 在不同平面上呈现物体的层析像。首先, 利用波前传感器采集真实物体的波前信息。接着, 运用单次快速傅立叶变换算法对光路中成像透镜的传递函数进行模拟, 制成含有该物光经透镜后的波前信息, 分别得到了实验所需的强度和相位灰度图片。然后, 通过两台空间光调制器对入射平行光场进行调制, 从而实现对物光经透镜后的光场进行波前重现。最后, 根据透镜的成像原理, 把CCD分别放置在物体前后两个成像面上即可得到层析的成像图。实验中分别在距离空间光调制器后2985 mm和3376 mm处观察所探测到的物体前后两个成像面的立体层析像。实验结果表明: 在模拟透镜的焦距为150 mm、计算衍射距离为150 mm的情况下, 前后两个成像面在x、y轴方向上的横向放大率分别为(11, 108)和(134, 109), 与利用透镜成像公式计算得到的横向放大率(1, 12)相比, 相对误差分别为(106%, 8%)和(117%, 8%)。角扩散度分别为295°和261°, 其相对误差分别为26%和07%, 低于5%, 基本符合实验原理。实验结果证明了该方法的可行性, 为后续开展的三维显示与新的全息技术提供了有效的技术支撑。

On the basis of traditional interferometric holography technology, we propose a purely optical three-dimensional display holography technology. A spatial light modulator is used to realize wavefront reproduction of object beams from a real object and holographic images of the object are presented on different planes through tomography. First, a wavefront sensor is used to acquire the wavefront information of the real object. After that, a single fast Fourier transform algorithm is applied to simulate the transfer function of the imaging lens in the optical path and a phase grayscale image containing the wavefront information of the object light passing through the lens is prepared. Then, the incident parallel light field is modulated using two spatial light modulators to achieve wavefront reproduction of the light field passing through the lens. Finally, according to the imaging principle of the lens, a CCD is placed on the imaging surface of the two objects to obtain their tomography. The experimental results show that the stereoscopic tomographic image of the detected object is observed at a distance of 2985 mm and 3376 mm from the spatial light modulator when the focal length of the simulated lens is set to 150 mm and the calculated diffraction distance is 150 mm, respectively. The lateral magnifications of the two front and back imaging planes in the x and y axes are (11, 108) and (134, 109), respectively. Compared with the lateral magnification (1, 12) calculated by the lens imaging formula, these relative errors are (106%, 8%) and (117%, 8%). The angular spread is 295° and 261°, respectively, and the relative error is less than 5%, which confirms the experiment principals. The experiment provides an effective research method for the subsequent three-dimensional display and new holographic technology.