Studies Of Second-harmonic Talbot Effect And Double-grating Talbot Interferometry

Talbot effect refers to the phenomenon that self-imaging of a periodic object replicates at certain planes after the object without using any optical components when illuminated by incident lights. Research on Talbot self-imaging effect has a long history of-170years. People have done systematic work in its theory and applications. This thesis summarizes recent progresses about Talbot effect investigates the novel second-harmonic Talbot effect, and theoretically discusses double-grating Talbot interferometers.First, we present theoretical deductions about integer and fractional Talbot effect based on Fourier’s optics theory. We study the characteristics of the images of one-dimensional gratings and two-dimensional arrays at1/4,1/3, and1/2Talbot planes in theory. Also, we give theoretical analyses about the double-grating diffraction system and its applications in observations of phase objects, Moire fringe phenomenon, and so on.Second, we studies the second-harmonic (SH) Talbot effect in periodically poled LiTaO3(PPLT) crystals. The SH Talbot images are carefully recorded at different fractional Talbot planes. At the same time, based on Fresnel-Kirchhoff diffraction theory and angular spectrum theory, we numerically simulates the intensity distributions of the SH waves at different observation planes. The results show that duty cycle and the background of the array have certain influence on fractional SH Talbot images.Third, we present a series of theoretical calculations about double-grating systems. Using a phase-type object as a sample, we optimize the parameters of the double-grating system for better imaging.