1、documents作业激光原理与应用高斯.bmp);A1=A(:,122);x1=1:1:224;x2=-100:100;a2=exp(-x2.2/10);figureimshow(A);axis offtitle(fontsize12CCD采集的高斯光束光强分布plot(x2,a2,linewidth,1,color,baxis(-40 40 0 1.2)fontsize12实验测量高斯曲线plot(x1,A1,rfontsize12理论高斯曲线axis(50 200 0 180)画三维强度分布。取图片矩阵的中间层,用mesh命令画出三维图如图4所示。图4 三维强度分布由于读入的图片有一行白
2、边,需要手动去除掉,否则三维图会有一边整体竖起来,影响观察。最终的M文件如下。high, width, color = size(A);x=1:width;y=1:high-1;mesh(x, y, double(A(2:224,:,1);grid onxlabel(x),ylabel(y),zlabel(z三维强度分布再用matlab仿真理论上传播过程中高斯光束的变化这次先给出M文件:%Gaussian_propagation.m%Simulation of diffraction of Gaussian Beamclear;%Gaussian Beam%N:sampling numberN
3、=input(Number of samples(enter from 100 to 500)=L=10*10-3;Ld=input(wavelength of light in micrometers=Ld=Ld*10-6;ko=(2*pi)/Ld;wo=input(Waist of Gaussian Beam in mm=wo=wo*10-3;z_ray=(ko*wo2)/2*103;sprintf(Rayleigh range is %f mm,z_ray)z_ray=z_ray*10-3;z=input(Propagation length (z) in mmz=z*10-3;%dx:
4、step size dx=L/N;for n=1:N+1 for m=1: %Space axis x(m)=(m-1)*dx-L/2; y(n)=(n-1)*dx-L/2; %Gaussian Beam in space domain Gau(n,m)=exp(-(x(m)2+y(n)2)/(wo2);%Frequency axis Kx(m)=(2*pi*(m-1)/(N*dx)-(2*pi*(N)/(N*dx)/2; Ky(n)=(2*pi*(n-1)/(N*dx)-(2*pi*(N)/(N*dx)/2; %Free space transfer function H(n,m)=exp(
5、j/(2*ko)*z*(Kx(m)2+Ky(n)2); endend%Gaussian Beam in Frequency domain FGau=fft2(Gau);FGau=fftshift(FGau);%Propagated Gaussian beam in Frequency domain FGau_pro=FGau.*H;%Peak amplitude of the initial Gaussian beam Peak_ini=max(max(abs(Gau);Initial peak amplitude is %f mm,Peak_ini)%Propagated Gaussian
6、beam in space domain Gau_pro=ifft2(FGau_pro);Gau_pro=Gau_pro;%Peak amplitude of the propagated Gaussian beam Peak_pro=max(max(abs(Gau_pro);Propagated peak amplitude is %f mm,Peak_pro)%Calculated Beam Width N M=min(abs(x);Gau_pro1=Gau_pro(:,M);N1 M1=min(abs(abs(Gau_pro1)-abs(exp(-1)*Peak_pro);Bw=dx*a
7、bs(M1-M)*103;Beam width(numerical) is %fmm,Bw)%Theoretical Beam Width W=(2*z_ray)/ko*(1+(z/z_ray)2);W=(W0.5)*103;Beam width(theoretical) is %fmm,W)%axis in mm scale x=x*103;y=y*103;figure(1);mesh(x,y,abs(Gau)Initial Gaussian Beamx mmylabel(y mmaxis(min(x) max(x) min(y) max(y) 0 1)axis squarefigure(2
8、);mesh(x,y,abs(Gau_pro)propagated Gaussian Beam程序主要根据高斯光束的传播规律计算传播过程中任意z处的高斯光强分布。运行结果:Number of samples(enter from 100 to 500)=500wavelength of light in micrometers=0.568Waist of Gaussian Beam in mm=1ans =Rayleigh range is 5530.972982 mmPropagation length (z) in mm100000Initial peak amplitude is 1.000000 mmPropagated peak amplitude is 0.210252 mmBeam?width(numerical) is 1.940000mmwidth(theoretical) is 18.107635mm束腰半径处的理想高斯光强分布传播1m处的理想高斯光强分布传播10m处的理想高斯光强分布传播20m处的理想高斯光强分布传播30m处的理想高斯光强分布传播50m处的理想高斯光强分布传播100m处的理想高斯光强分布而用实验测得的光斑仿真的结果是:原始光斑的光强分布0.1m处1m处1.8m处5m处10m以后,已经基本是均匀强度的光斑
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