Thread Subject:

optical fourier transformation

hello,

Please help me to implementate in matlab an achromatic 2D fourier transformation.

when the system use a broadband illumination.

Regards
sonia

This is a massive request for your first posting...what have you done so far?

"sonia " <sonia_elwardi@yahoo.fr> wrote in message <i3eedl$d45$1@fred.mathworks.com>...
> hello,
>
> Please help me to implementate in matlab an achromatic 2D fourier transformation.
>
> when the system use a broadband illumination.
>
> Regards
> sonia

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.

ImageAnalyst <imageanalyst@mailinator.com> wrote in message <372af4d7-9574-4aba-983b-f92f2263c76a@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
 

Well, what are your formulas? It's been over 20 years since I got my
Ph.D. in optics and I don't remember the formulas off the top of my
head.

"sonia " <sonia_elwardi@yahoo.fr> wrote in message <i3ff7c$2jn$1@fred.mathworks.com>...
> ImageAnalyst <imageanalyst@mailinator.com> wrote in message <372af4d7-9574-4aba-983b-f92f2263c76a@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?

On Aug 5, 8:32 pm, "Joseph " <don'twannapos...@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

Right, I just assumed it was homework


ImageAnalyst <imageanalyst@mailinator.com> wrote in message <c0ee7d7a-56cc-4113-9cdd-aa084f20baa2@z10g2000yqb.googlegroups.com>...
> On Aug 5, 8:32 pm, "Joseph " <don'twannapos...@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

ImageAnalyst <imageanalyst@mailinator.com> wrote in message <c0ee7d7a-56cc-4113-9cdd-aa084f20baa2@z10g2000yqb.googlegroups.com>...
> On Aug 5, 8:32 pm, "Joseph " <don'twannapos...@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

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.