Coherence Modulation And Spectral Shifts Of The Partially Coherent Light

The partially coherent beam is between the completely coherent beam and completely incoherent beam,almost all of the beams in our lives belong to the partially coherent class.The completely coherent beam and the completely incoherent beam never existed.The research shows that the completely coherent light transmission will have bad effects,such as speckle,focus shift,edge effect and so on.Relatively speaking,the beam's coherence decreases to partially coherent beams,which will reduce the above adverse effects and the intensity distribution in the transmission will be more homogeneous.It will make the shape of beam better and the transmission efficiency will be higher.Based on the basic theory of beam coherence and transmission,this paper discusses the structure and transmission characteristics of two classical different structures of partially coherent light.The first is the Gauss-Schell model beam,and the second is the Gauss type partially coherent beam associated with the special spatial association of the Hermite type.The main contents of the study are as follows:First,the Gauss-Schell model beam passing the 4f optical system was researched in the theoretical and Experimental,it could be calculated by using the Collins formula,and the array filter with a small hole in the surface of the spectrum in the 4f optical system.The results show that adjusting the small hole of frequency plane will reshape beam characteristics of source plane,but also can adjust the initial radius on the plane and the coherence length,which was closely related to the beam parameters.Secondly,based on the Association for special Hermite type spatial association of partially coherent beams,the partially coherent light is constructed from the scalar and vector.we analyzed the transmission process of the above beams,and studied them in free space through a thin lens after the transmission spectrum changes in the process,we found that the beams will produce red and blue shift,the phenomenon in the transmission process is significantly different,the number orders of Hermite correlation function of spectral shift has obvious effect.It provides an important theoretical basis and guidance for future experiments to carry out relative spectral shift of partially coherent beams associated with special spatial correlation of Hermite type.