Effects Of Aberration On The Focal Switch

Beam focusing is one of the most interesting subjects in the application of high power laser beams. Further studies on beam focusing are of great significance for lasers application and design of optical system. In the practice work, aberrations exist in beams and lens more or less, so to study the effects of aberration on focal switch is very necessary. The present thesis is devoted to study effects of aberration on focal switch properties of beams. The main results achieved in this thesis can be summarized as follows:1. From the Huygens-Fresnel diffraction integral (Collins formula), recurrence equations for the axial irradiance of tilted phase H-G beams through a system with the aperture and lens separated are derived, to study the influence of tilted phase on the focal switch. The study shows that the tilted phase coefficient (c₂) is closely relative to the appearance of focal switch. If c₂ is relatively small and other parameters are fixed, and the truncation parameter within the certain region of α_{c min} <α<α(c max), we can observe the focal switch phenomenon. But when the tilted phase coefficient is increased up to a certain region, truncation parameter can be anything bigger than the critical minimum, no critical maximum existing.2. We investigate the focal switch phenomenon of a tilted phase L-G beam passingthrough a system with the aperture and lens separated. The results demonstrate that the tilted phase affects not only the relative shift and the...