Investigations On The Talbot Effect And Moiré Effect Of The Square-Aperture Microlens Array

In the information age, we not only need to update more devices to obtain, control and transmission the information, but also put forward higher requirements to the speed, quality and diversity of information. To achieve these goals, we need different optoelectronic devices to control light, Such as imaging, focusing, coupling, splitting, modulation and other acts. Microlens array as an important microoptical component is used in various fields, such as the parallel confocal scanning system, and it’s the key component of the wave-front sensing.Square-aperture planar microlens array is an optical device which is fully taken into account the light receiving area and filling coefficient. In addition to the regular features, to research the other properties are also the important aspect. When monochromatic light vertically incident on the periodic structure such as transmission grating, we observe the self-image of the periodic structure along the optical axis direction. The phenomenon is called self-imaging or Talbot effect. When monochromatic light incident on periodic microlens array, the self-imaging phenomenon is appeared along the optical axis. So we discuss the Talbot effect of the microlens array.In studying the optical properties of the microlens array, we found the Moiré effect about microlens array with corresponding micrographics array. Moiré pattern is very sensitive for subtle displacement, deformation and rotation. So it is used to optical detection, optical alignment and document encryption security and so on. Studying the Moiré effect of microlens array will further expand the applications.The main contents are as follows:The Talbot effect of the square-aperture microlens array is studied theoretically and experimentally. The complex wave amplitude distribution of this array in the Fresnel diffraction field is analyzed with the optical transfer function to resolve the Talbot image situation. In the experiment, three alternating images appear at certain distance, and the experimentally measured imaging distance is consistent with the theoretical value. In addition, the Talbot sub-image imaging law is invariant when the parameters of the square-aperture microlens array changing. The Talbot sub-image image elements overlap, when the center distance is larger than one time and simultaneously shorter than twice aperture diameter. The clear Talbot sub-images with checkerboard-shaped distributions of the square-aperture microlens array are observed in the fractional Talbot planes. It will broaden the practical application of the square-aperture microlens array.The Moiré pattern is appeared when the translucent hole array overlapping the same period micrographics array. The Moiré pattern is slightly enlarged graphic. We observed the same phenomenon of Moiré pattern about microlens array and explored the Moiré display mechanism.