optical fourier transformation
in [Matlab]
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From: Joseph on 5 Aug 2010 20:32 "sonia " <sonia_elwardi(a)yahoo.fr> wrote in message <i3ff7c$2jn$1(a)fred.mathworks.com>... > ImageAnalyst <imageanalyst(a)mailinator.com> wrote in message <372af4d7-9574-4aba-983b-f92f2263c76a(a)q22g2000yqm.googlegroups.com>... > > sonia: > > What is an "achromatic 2D fourier transformation"? How does that > > differ from a regular 2D FT on a 2D array? And MATLAB doesn't do > > anything optically, just numerically. To do an optical FT, you'd need > > an optical bench/table with lenses, transparencies, etc. > > Hi thanks for your answers, > > I want to implementate my architecture with matlab, to simulate the real properties of each element . > I know that the regular 2D FT can be realized with matlab by the function (fft2). > In this case, we used a monochromatic light (a single wavelength (lambda0), and the used lens is caracterised by a constant focal distance f). > > but, when the system is illuminated by a temporally broadband light, there is an interval of [lambda_min ... lambda_max], So we must use an achromatic lens with a variable focal length.... > I don't know > - haw can I write a broadband ligth in a spatial system. > -haw we can write an fft2 when the distance focal change with lamdba. > > > REgards > Sonia > Quick question - what exactly are you simulating? If your lens is achromatic, shouldn't it affect all your wavelengths the same way?
From: ImageAnalyst on 5 Aug 2010 20:40 On Aug 5, 8:32 pm, "Joseph " <don'twannapos...(a)nopers.com> wrote: > Quick question - what exactly are you simulating? If your lens is achromatic, shouldn't it affect all your wavelengths the same way? ---------------------------------------------------------------------------- Joseph: Depends on how you define it, or where you look. Normally the index of refraction of glass depends on wavelength and different colors of light get focused at different places. However if you're doing some theoretical homework exercise, you might ignore that and assume there is no dependence of index of refraction on wavelength. Maybe she's doing that. On the other hand, you might assume the real world situation where the index of refraction does depend on wavelength. An achromatic imaging system, such as a simple achromat lens (http://en.wikipedia.org/wiki/ Achromat), will focus all the wavelengths of light to the same place, but they will differ in position as you move along the optical path, so that different colored rays of light don't always overlap everywhere. See the figure in the wikipedia article for an illustration. Image Analyst
From: Joseph on 5 Aug 2010 23:54 Right, I just assumed it was homework ImageAnalyst <imageanalyst(a)mailinator.com> wrote in message <c0ee7d7a-56cc-4113-9cdd-aa084f20baa2(a)z10g2000yqb.googlegroups.com>... > On Aug 5, 8:32 pm, "Joseph " <don'twannapos...(a)nopers.com> wrote: > > Quick question - what exactly are you simulating? If your lens is achromatic, shouldn't it affect all your wavelengths the same way? > ---------------------------------------------------------------------------- > Joseph: > Depends on how you define it, or where you look. > > Normally the index of refraction of glass depends on wavelength and > different colors of light get focused at different places. However if > you're doing some theoretical homework exercise, you might ignore that > and assume there is no dependence of index of refraction on > wavelength. Maybe she's doing that. > > On the other hand, you might assume the real world situation where the > index of refraction does depend on wavelength. An achromatic imaging > system, such as a simple achromat lens (http://en.wikipedia.org/wiki/ > Achromat), will focus all the wavelengths of light to the same place, > but they will differ in position as you move along the optical path, > so that different colored rays of light don't always overlap > everywhere. See the figure in the wikipedia article for an > illustration. > Image Analyst
From: sonia on 6 Aug 2010 18:31 ImageAnalyst <imageanalyst(a)mailinator.com> wrote in message <c0ee7d7a-56cc-4113-9cdd-aa084f20baa2(a)z10g2000yqb.googlegroups.com>... > On Aug 5, 8:32 pm, "Joseph " <don'twannapos...(a)nopers.com> wrote: > > Quick question - what exactly are you simulating? If your lens is achromatic, shouldn't it affect all your wavelengths the same way? > ---------------------------------------------------------------------------- > Joseph: > Depends on how you define it, or where you look. > > Normally the index of refraction of glass depends on wavelength and > different colors of light get focused at different places. However if > you're doing some theoretical homework exercise, you might ignore that > and assume there is no dependence of index of refraction on > wavelength. Maybe she's doing that. > > On the other hand, you might assume the real world situation where the > index of refraction does depend on wavelength. An achromatic imaging > system, such as a simple achromat lens (http://en.wikipedia.org/wiki/ > Achromat), will focus all the wavelengths of light to the same place, > but they will differ in position as you move along the optical path, > so that different colored rays of light don't always overlap > everywhere. See the figure in the wikipedia article for an > illustration. > Image Analyst Hello, It is a section in my research work, A sample of architecture that I want to simulate is illustrate in this paper: LANCIS J. ; TAJAHUERCE E. ; ANDRES P. ; MINGUEZ-VEGA G. ; FERNANDEZ-ALONSO M. ; CLIMENT V. ''Quasi-wavelength-independent broadband optical Fourier transformer" Optics Communications Volume 172, Issues 1-6, 15 December 1999, pp 153-160 . Regards Sonia
From: ImageAnalyst on 6 Aug 2010 19:30
Sonia Well okay then. I, of course, don't have that paper nor am I going to order it. But just program up the formulas in it. Ask the authors for advice if you need it - maybe they'll be eager/flattered to help. you I can see that you didn't ask a MATLAB question, so... Good luck with your research. |