Study Of Propagation Properties Of Apertured Laser Beams

The propagation property of apertured laser beams (propagation and control of actual high-power lasers) is a complicated and challenging subject in the field of high-power-laser technology and a frontier subject many researchers devoting to. The present thesis is devoted to studying propagation properties of apertured laser beams confronted in the application of high-power-laser technology. The main results achieved in this thesis can be summarized as follows:1. By means of the Fourier series expansion, an approximate analytical propagation equation of flattened Gaussian beams(FGBs) passing through an apertured paraxial ABCD optical system is derived, and illustrated with numerical examples, when the transmissivity of the aperture is T(x) = cos( x). The hard-edged aperture can be regarded as a special case of = 0.2. By using the Fourier series expansion, approximate analytical propagation equations of laser beams through a paraxial optical ABCD system with different apertures are derived. The hard-edged aperture can be regarded as a special case treated here, while the other apertures can also be dealt with as a hard-edged aperture. Numerical calculations show the advantage of our method and the consistency with the results by means of the Collins formula.3. Based on the generalized Huygens-Fresnel diffraction integral, a recurrence propagation equation of Hermite-Gaussian (H-G) beams through a paraxial optical ABCD system with hard-edged aperture is derived, which permits us to obtain the analytical propagation expression for H-G beams of any order. The advantages of our analytical results are analyzed, and the application is illustrated with numerical examples.4. Starting from the Collins formula, a recurrence equation ofHermite-cosine-Gaussian (HCG) beams propagating through a paraxial ABCD system with a hard-edged aperture is derived, from which the analytical propagation expressions for apertured HCG beams of any order can be derived by using the recursive algorithm. The validity and advantage of our results are confirmed and illustrated by numerical calculations.5. The focusing properties of Gaussian beams through a compound optical system arediscussed. Based on the matrix optical method, formulae of the beam width at the focal plane and imaging distance of focused Gaussian beams through the system are derived.6. Binary optical elements for spatial beam shaping are designed by using IIIO algorithm. For Gaussian beams the shaping result is given by using two different ways.7. Propagation properties of flattened Gaussian, Bessel-Super-Gaussian and Laguerre-Gaussian beams are studied by using the Collins formula in the frequency-domain and Hankel transform. The results are compared with those by means of the Collins formula in the space-domain, and the advantage of the method is discussed.