How can I simulate PSF of incoherent light?

snowstarlele

Quote by Andy Resnick

I'm not sure what you mean by 'assumption'...? For example, using the Stokes vector (S0, S1, S2, S3) to describe the polarization state, the total intensity is S0. You can choose any basis states for polarization: x and y, left- and right-circular, radial and tangential, etc.

Hi Andy Resnick,

Thanks,

Here I've enclosed one attachment, which is according to your suggestion.
I = 1/2[I_r + I_t].

I was confused the difference between incoherent light and unpolarized light. I think I = 1/2[I_r + I_t] is more suitable for unpolarized light. do you think <<1/2[I_r + I_t]>> can reflect the incoherent but linear polarized light ? (such as the light from white light source + filter+polarizer).

thanks again

Regards

DrDu

I looked at the definition of the PSF and found that the answer to your original question is very simple: The point spread function defines the spread of light from a point source when passing through some optics. But the light from a point source is always completely spatially coherent and, if monochromatic, also temporally coherent.

snowstarlele

Quote by DrDu

After having proposed to average over polarizations myself first, I now rather think that you have to average over waves entering under slightly different angles or from different points (depending on the characteristics of the incoherent light source!)
Generally, I find this thread hard to follow: E.g. the article you cite does not mention point spread function.
Maybe you could just write down the expression you found for coherent light and explain it?

Hi

Thank you very much for your post.

I tried with small angle. please find the attachment. I also put the formula for PSF.

Thanks again for your help,

snowstarlele

Quote by DrDu

After having proposed to average over polarizations myself first, I now rather think that you have to average over waves entering under slightly different angles or from different points (depending on the characteristics of the incoherent light source!)
Generally, I find this thread hard to follow: E.g. the article you cite does not mention point spread function.
Maybe you could just write down the expression you found for coherent light and explain it?

Sorry forgot to put attachment. here it is.

DrDu

What are r_P, theta_P, phi_P, and theta, phi? Where is the point light source?

snowstarlele

Quote by DrDu

What are r_P, theta_P, phi_P, and theta, phi? Where is the point light source?

r_P, theta_P, phi_P, image coordinate
theta is open angle of objective lens, theta=arcsin(NA/n). phi is spatial angle at lens coordinate. there is one papar from wolf explain detailly about transfrom from Cartesian coordinate to polar coordinate.

Here it is the paper . please find the attachment.

Thanks for your help.

Regards.

the meaning of formula is the supperposition of all light rays which is diffracted from lens aperture.

DrDu

Can't see the paper

snowstarlele

Quote by DrDu

Can't see the paper

Does it works now? I enclosed again . It's so weird.

if it still not be able to upload, please find it on google by title "Electromagnetic diffraction in optical systems II. Structure of the image field in an aplanatic system"

Sorry for the incontinence.

Regards.

DrDu

It didn't work but I had a look at the paper.
As I said I don't see any problem as the light from a point source is always coherent.
Incoherence enters when you want to calculate the image of an extended object or source.

Andy Resnick

Quote by snowstarlele

<snip>do you think <<1/2[I_r + I_t]>> can reflect the incoherent but linear polarized light ? (such as the light from white light source + filter+polarizer).

If I understand you correctly, no- while you started with incoherent light, you ended up with coherent light. We may be getting off track here- are you still asking how to compute the incoherent PSF, or are you now asking something else?

Andy Resnick

Quote by DrDu

<snip> But the light from a point source is always completely spatially coherent and, if monochromatic, also temporally coherent.

Usually that's correct- but polarization is another degree of freedom.

DrDu

Quote by Andy Resnick

Usually that's correct- but polarization is another degree of freedom.

Sure, but adding two intensities is not really a problem. Furthermore, the case of unpolarised light has been treated in the article by Richards and Wolf to which the OP apparently was referring all the time:

Richards, B., & Wolf, E. (1959). Electromagnetic diffraction in optical systems. II. Structure of the image field in an aplanatic system. Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences, 253(1274), 358-379.

Andy Resnick

Quote by DrDu

Sure, but adding two intensities is not really a problem. Furthermore, the case of unpolarised light has been treated in the article by Richards and Wolf to which the OP apparently was referring all the time:

Richards, B., & Wolf, E. (1959). Electromagnetic diffraction in optical systems. II. Structure of the image field in an aplanatic system. Proceedings of the Royal Society of London. Series A. Mathematical and Physical Sciences, 253(1274), 358-379.

Right- and the OP was (originally) trying to understand why their simulation was not returning expected results.

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DrDu Recognitions: Science Advisor	I looked at the definition of the PSF and found that the answer to your original question is very simple: The point spread function defines the spread of light from a point source when passing through some optics. But the light from a point source is always completely spatially coherent and, if monochromatic, also temporally coherent.