Referenceless phase holography for reconstruction of complete optical wave fields for metrology and displays II (RELPH II)

无参考位相全息术(Relph)是一种用于显示任意强度和位相分布的3D场景的概念。它不仅在显示水平、垂直和运动视差方面优于其他3D显示方法，而且不存在适应-会聚冲突，而且在产生无DC项和无孪生图像方面也优于传统全息术。该技术基于两个硅基液晶(LCOS)型空间光调制器(SLM)对两个准直波的干涉。虽然目前市场上还没有足够高的空间带宽产品，但这种有前景的方法的基础已经为未来的3D电视和3D电影奠定了基础。在项目的第一阶段，基本理论的存在和唯一性已经得到了证明，并从实验上证实了方法的可行性。对样例3D场景的显示实验证明了3D特征的焦深、物体遮挡和视差。很明显，Relph需要对两个LCO进行精确的相互调整。通过对样本物体的实验，提出了一种LCOS的刚体相互调整策略。但是，必须通过测量变形并在两个LCO的相位分布中添加校正的相位分布来消除叠加在期望的复波场上的剩余杂散干扰图案。在这里提出的下一阶段计划中，必须开发和实施这种校准。每个LCOS的变形都必须由外部干涉仪测量。这些测量的结果可以与相移测量的结果进行核对，相移测量的结果产生了两个错误的相位分布的差异。激光二极管的使用将被调查，它们在空间或时间多路复用彩色显示中的组合也将是一个问题。将分析要显示的3D场景的数字全息捕获，目的是发现从全息数据计算相对数据的容易和快速的过程。为了获得更好的视觉效果，必须提高Relph产生的波场的光学放大倍数，并在计算过程中对横向和纵向的不同放大倍数进行补偿。嵌入到Relph方法的性能评估中，将调查和执行对像斑点之类的图像退化的抑制。

Referenceless phase holography (RELPH) is a concept for displaying 3D scenes with arbitrary intensity and phase distributions. It is not only superior to other 3D display methods in showing horizontal, vertical, and motion parallax while exhibiting no accommodation-convergence conflict, but also is better than conventional holography in producing no dc-term and no twin images. The technique is based on the interference of two collimated waves which are phase modulated by two spatial light modulators (SLM) of liquid crystal on silicon (LCOS) type. Although today still no SLMs with a space-bandwidth-product high enough are offered on market, the foundations of this promising method for future 3D TV and 3D movies have to be developed now.In the first phase of the project existence and uniqueness of the underlying theory has been proven and the feasibility of the method was confirmed experimentally. Experiments displaying sample 3D scenes proved the 3D features depth of focus, object occlusion, and parallax. It has become obvious that RELPH requires an exact mutual adjustment of the two LCOS. Experiments with a sample object suggested a strategy for mutual rigid body adjustment of the LCOS. But a remaining spurious interference pattern superposed to the desired complex wave field has to be eliminated by measuring the deformations and adding correcting phase distributions to the phase distributions of both LCOS.In the next phase of the project, which is proposed here, this calibration has to be developed and implemented. The deformation of each LCOS has to be measured by an external interferometer. The results of these measurements can be checked against the results of phase-shifting measurements, which yield the difference of the two erroneous phase distributions. The employment of laser diodes will be investigated, their combination in spatially or temporally multiplexed color display also will be an issue. The digital holographic capture of the 3D scenes to be displayed will be analyzed with the objective to discover easy and fast procedures to calculate the RELPH-data out of the holographic data. The optical magnification of the RELPH-generated wave fields for better vision has to be improved with compensation of the different magnifications in lateral and in longitudinal direction already in the calculation process. Embedded into a performance assessment of the RELPH method the suppression of image degradations like speckles will be investigated and carried out.