Yosuke Koga

Effect of dummy area in the generation of computer-generated hologram to improve the reconstruction diffraction efficiency

In most cases of the generation of computer-generated hologram, a zero-valued dummy area is usually added to the desired object in order to avoid the disturbance of high order reconstruction. The high order reconstruction not only disturbs the zero order reconstruction but also decreases the zero order reconstruction diffraction efficiency. In this study, we show a method to improve the zero order reconstruction diffraction efficiency by using a finite dummy area. According to the structure of a general computer-generated hologram, that is each calculated computer-generated hologram point has the same square size, then the high order reconstruction is the product of the zero order reconstruction and a sampling function with a scale factor. We use computer simulation to show the effect of dummy area in the improvement of the zero order reconstruction diffraction efficiency. According to our simulation results, we find that the zero order reconstruction diffraction efficiency increases as increasing the size of dummy area. In addition, we also find that the on-axis reconstruction has a higher reconstruction diffraction efficiency that the off-axis ones.