How to implementation DFT (discrete fourier transform) to intensity?

2 次查看（过去 30 天）
MOHD
MOHD 2014-6-17
编辑： Star Strider 2014-6-18
Here I am trying to calculate intensity of Xpolarized light by using DFT (discrete fourier
transform) instead of fft, by using DFT I am getting intensity in 4th quadrant only (Which is
shown in figure (1)). How can I get intensity in total plane. Can some help me in this regard
clear all;
clc;
lose all;
[kx,ky]=meshgrid(-1:2/21:1);
circ=sqrt(kx.^2+ky.^2)<1;
alp=asin(0.95);
k0=1/sin(alp);
kz=sqrt(k0^2-(kx.^2+ky.^2));
GX=sqrt(k0./kz).*((k0*ky.^2+kz.*kx.^2)./(k0*(kx.^2+ky.^2)));
GY=sqrt(k0./kz).*((kz-k0).*kx.*ky)./(k0*(kx.^2+ky.^2));
la=1;
lb=0;
EX=(GX.*la-rot90(GY.*lb, 3));
M=22;
N=22;
F=zeros(22,22);
for Xpx=1:M
for Xpy=1:N
F(Xpx,Xpy)=sum(sum(EX.*exp(1j*2*pi*(((Xpx.*kx)/M)+((Xpy.*ky)/N)))));
end
end
F=F/(M*N);
I1=F.*conj(F);
figure(1)
imagesc(I1),colormap gray;axis image; axis off;
Thank you very much in advance Your Mohd. Gaffrar

请先登录，再回答此问题。

回答（1 个）

Dishant Arora
Dishant Arora 2014-6-17
Use the logarithmic scale to image the fourier transform. Fourier transform results in large dynamic range, thereby logarithmic scale makes it easy to see small signal components in the presence of large ones. Probably you can do:
imagesc(log(I))
  2 个评论
Dishant Arora
Dishant Arora 2014-6-18
编辑：Dishant Arora 2014-6-18
The kx and ky you are using inside the loop for dft calualation, shouldn't they be integers. They need to be indices not spatial coordinates. Make appropriate changes to your code and cross check with built in fft2. I tried and it works for me.

请先登录，再进行评论。

类别

在 Help Center 和 File Exchange 中查找有关 Discrete Fourier and Cosine Transforms 的更多信息

标签

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by