Kozma A, Massey N
Appl Opt. 1969 Feb 1;8(2):393-7. doi: 10.1364/AO.8.000393.
The known techniques for making incoherent holograms succeed for an object containing a small number of points; however, they fail in practice for an object with a great many discrete points or for an object with a continuous intensity distribution. This results because the intensity pattern generated in incoherent holography in a superposition of random intensity patterns generated by the individual object points. Thus, the intensity pattern contains a large bias level which masks the relatively small spatial variations of the pattern in the recording film grain noise. This paper describes a technique for eliminating the bias. By introducing a narrow band time modulation of the light in one path of an interferometer used to generate the hologram intensity pattern, the spatially varying part of the hologram intensity pattern is modulated at the time frequency, while the bias part is unmodulated. The bias part can then be eliminated by performing a point-by-point time correlation over the hologram plane. Experimental results are presented.
制作非相干全息图的已知技术对于包含少量点的物体是成功的；然而，对于具有大量离散点的物体或具有连续强度分布的物体，这些技术在实际应用中却失败了。之所以会这样，是因为在非相干全息术中生成的强度图案是由各个物体点生成的随机强度图案叠加而成的。因此，强度图案包含一个较大的偏置电平，它掩盖了记录胶片颗粒噪声中图案相对较小的空间变化。本文描述了一种消除偏置的技术。通过在用于生成全息图强度图案的干涉仪的一条光路中引入光的窄带时间调制，全息图强度图案的空间变化部分在时间频率上被调制，而偏置部分未被调制。然后，可以通过在全息图平面上逐点进行时间相关来消除偏置部分。文中给出了实验结果。
