Propagation And Transformation Of Laser Beams Through Optical System With Aperture

In the usual lives, laser beam need either propagation through optical system to interreact with other material or in order to satisfy the parameter require. Aperture is a kind of familiar component in optical system. With the development of laser technology, The study of different beams propagation through aperture-lens system have changed with each passing day. In this dissertation, different beams propagation through aperture-lens system are discussed. The main work of the dissertation is as follows:The propagation equations of Hermite-Laguerre-Gaussian beams through circular hard-edged aperture have been derived. In addition, based on the relations between Hermite and Laguerre Gaussian modes and recurrence algorithm, recurrence formulas of Laguerre-Gaussian (LG) beams propagating through a paraxial ABCD optical system with a rectangular aperture are derived. As an application example, the transformation of LG beams through a system with rectangular aperture and lens separated is studied numerically. The results provide a useful method for the transformation of beams with different geometrical symmetry.The propagation and transformation of elegant Laguerre-Gaussian beams(ELGBs) by a serrated aperture are studied using the Huygens-Fresnel diffraction integral. The diffraction characteristics of the serrated aperture are analyzed. The result show that the modulations of axial intensity of ELGBs diffracted by the serrated aperture can be suppressed, the transversal intensity distributions become more uniform and the filling factor is also increased. The analytical express that the axial intensity distribution of laser beams relate to the parameter of serrated aperture, so we can make the most Suitable serrated aperture in the practically use.Programming use mathematic soft, A detailed comparative study of diffraction properties of laser beams by hard-edged, super-Gaussian and serrated apertures is performed, the result show that different apertures have different applied area and advantages.