Liquid crystal display as spatial light modulator for diffractive optical elements and the reconstruction of digital holograms

摘要

Liquid crystal displays, originally designed and fabricated for projection systems, are often used as spatial light modulators in optical correlators or in fringe projection systems. Operating in a linearized phase mode, they can achieve a performance to be applicable as diffractive elements. An adapted driver electronics and adapting measurements of the phase modulation behavior can lead to a dynamic phase modulating system with an almost linear modulation and a maximum phase shift of 2π. The electronic system can directly address the graphics card signal or can picture various video standards. So, computer generated holograms can be addressed at video frame rates. The limiting parameters of the performance are mostly due to physical boundary conditions, such as pixel number and size, response time, transmission etc.. We can assume that the fast growing micro-structuring technology will serve us soon with displays of higher resolutions and efficiency. Beam shaping elements, two-dimensional holograms and the reconstruction of digital holograms will be shown. The latter opens new possibilities for non-destructive testing devices especially in the field of holographic interferometry. We will show results of different systems and derive boundary conditions for applications in holographic reconstruction of coherent masks.