标题: How to calculate lens cut off frequency [打印本页] 作者: gudong 时间: 2004-1-9 10:21 标题: How to calculate lens cut off frequency is lens cut off frequency the same as MTF?
Say I have a periodic bar pattern as input, distance 3f/2 away there is F/4 lens, and after distance 3f I should have the image.
my solution is: diffraction limit is 1.22*wavelength*3f/D=14.64wavlength, then on the image plane, I assume the image of two bars is 14.64*wavelength, then at object plane, the cloest distance is 7.32*wavelegnth.
This number is very high, assume wavelength is 0.5um, it is 300+ cycles/mm. but normal lens MTF is less than 100. Where did I do wrong?
Thanks作者: gudong 时间: 2004-1-11 06:42 标题: How to calculate lens cut off frequency nobody help me on this? this is a question on our PhD qualify exam a couple years ago.