Angular Spectrum and Fresnel Diffraction
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- เผยแพร่เมื่อ 9 ก.ย. 2024
- / edmundsj
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Rather than attacking propagation directly using the Fresnel Integral, we can instead take the (much simpler) route of figuring out how individual plane waves propagate, and then summing them all up at the end to figure out what the electromagnetic field is some distance away.
This is part of my graduate series on optoelectronics / photonics, and is based primarily on Coldren's book on Lasers as well as graduate-level coursework I have taken in the EECS department at UC Berkeley.
Hope you found this video helpful, please post in the comments below anything I can do to improve future videos, or suggestions you have for future videos.
Fantastic video, thank you!
Thank you for the wonderful video. I have one question:
According to Goodman's Introduction to Fourier Optics, the fresnel propagation transfer function should be exp(j*\pi*\lambda*d*x^2)*exp(j*k*d) where exp(j*k*d) is a constant phase delay term that can be dropped. The key is that the propagation distance d should be in the numerator, not the denominator. However, the video (at 2:00) had d in the denominator.
Was that a typo?
Good ! What about frequency spectrum? Does monochromatic wave create additional frequency components and change spectrum at Fresnel diffraction?
Nope, if you have a monochromatic wave you will always have a monochromatic wave. The frequency will only change if you have some weird nonlinearity going on or if you have moving objects due to the Doppler effect.
The only thing missing is a good example of all this stuff.