无狭缝计算全息图的白光再现

Reconstruction of No-Slit Computer-Generated Hologram with White-Light Illumination

利用彩虹全息是实现白光全息的常用方法,由于记录过程中引入狭缝使得再现像的视场非常狭小,且只有水平视差。在计算全息中模拟无狭缝记录,通过博奇编码获得菲涅耳全息图,以视频信号输入液晶板(LCD)显示,在白色发光二极管(LED)照明下获得同时具有水平和垂直视差的彩色全息再现像,大小为15 mm×15 mm。调整物面采样间距和滤波小孔孔径以减小色模糊、提高再现光的空间相干性,获得的白光再现像与彩虹全息图的再现像相比,前者虽然牺牲了一定的像质,但垂直视场角远大于后者,且整个系统简单紧凑、操作方便,再现像视场范围大,利于观察和接收,另外宽光谱光源和空间光调制器的使用为实现实时三维彩色全息打下了基础。

Rainbow holography is a major method in white-light holography, which is lack of vertical parallax due to introducing a slit that reduces the view zone of reconstructed images in recording process. A Fresnel hologram without slit simulation is computed by Burch coding, and displayed on liquid crystal display （LCD） as video frequency signals; color reconstructed images with full parallax are obtained by white-light illumination. By adjusting sample interval and pinhole filter to reduce color blurring and enhance the spatial coherence of reconstructed light, reconstructed images with much wider vertical view zone are achieved comparing with the results of rainbow computer-generated hologram （CGH）, though the image quality of the former is a little worse than the later for the money. Not only the whole system is simple and easy operated, but also the reconstructed images have large view zone in favor of observing and receiving. Wide-spectrum light source and the spatial light modulator are used in this system, which is ready for the development of real-time three-dimensional （3D） color digital holography.