Modulating The Statistical Properties Of A Vector Partially Coherent Beam By A 4f Optical System

For a laser beam,some parameters like the intensity distribution,state of polarization,degree of polarization and the spectrum which will change through propagation are some basic characters of a beam.It is also important to study the spatial coherence of a laser beam.Many researches have been carried out based on modulating the statistical properties of coherence.Because of many significant characters such as the better imaging quality than high coherence laser beam and the maintenance of good quality in complex environment,partially coherent beams have many significant applications in some fields.Many researchers study hard about modulating the statistical properties of partially coherent beams.A 4f optical system is applied to modulate the statistical properties of a vector partially coherent beam.We find that the intensity distribution and the degree of coherence of an incident radially polarized Gaussian Schell-model beam can be shaped simultaneously by a 4f optical system with an amplitude filter in the frequency plane.By controlling the parameters of the amplitude filter and the coherence length of the incident beam precisely,the shaped beam can display periodic spatial coherence in the source plane and form intensity lattices with radially polarization in the far field.We will introduce the development of partially coherent beam in chapter 1,and also we will have a revise on 4f optical system.We will have a simple introduction about the combination of the applications of partially coherent beam and the 4f optical systemTo get some main results in this paper,we will introduce the physical and mathematical basis in chapter 2.It is important to generate a partially coherent beam and get the expression of partially coherent beam.We will also introduce the beam coherence-polarization matrix and discuss the propagation properties of partially coherent beam and the application of Collins formula.Finally,the method of describing polarized beams is introduced,and the beam coherent-polarization matrix of radially polarized Gaussian Schell-model beam at the source plane is theoretically constructed.In chapter 3,based on the characters of 4f optical system,a new beam is constructed theoretically.This beam is generated from radially polarized Gaussian Schell-model beam and shaped by a 4f optical system with an optical amplitude filter in the frequency plane.Both intensity distribution and the degree of coherence dissatisfy the Gaussian distribution.In addition,the state of polarization is shaped.As a result,we have constructed a novel lattice beam theoretically.In chapter 4,we carry out the experiment.The experimental setup and results of the experiment are briefly introduced.The experimental results agree well with the theoretical results to verify the accuracy of the theory.Finally in chapter 5,we summarize and look forward to the future development.