Simulation of paraxial pinhole photon sieves model based on Fresnel zone plates

Abstract

Soft X-rays has applications in many fields because of its special characters. Therefore the focusing and imaging is important to those applications. The traditional refractive lens to focus soft x-rays has some shortcomings. Fresnel zone plates can overcome these shortcomings. However, it presents new problems, that is, the resolution is limited by the width of the outermost zone. Kipp et al2 developed a novel diffractive optical element called the photon sieve. It can overcome the limitations of Fresnel zone plates. According to Fresnel-Kirchhoff diffraction integral, one can present the far field model3 and obtain the radius and the central position of pinholes on the conditions of far field and near field correction. We show the simulated figures and the diffraction pictures when the number of pinholes is 20, 40 and 80 respectively by imitating this model. Then we compare some diffraction pictures of the photon sieves with different number of pinholes to monochromatic light, and analyze the influence of the number of pinholes to the ability of focusing. The result indicates that the pinhole photon sieve has higher precision focusing ability than zone plates. This model is simple in theory and it has facility in operation.