Hi Amit

Could the image simulation be a solution to your problem? I have copied the link to the article: How to simulate high resolution images

Sandrine

Hi Sandrine,

Thank you for the response.

In the beginning the thought of image simulation also crossed my mind.

However, I am little sceptical, because even if I set the display settings as PSF grid, the evaluation is only qualitative.

If I can evaluate the PSF quantitavely, it would help me out in validation of the simulations. 

Now since the deformation of the image plane effectively means that the image surface is at different disctances from the last optical surface, I want to have a qualitative value of paramaters (here I suggested PSF) at different positions on the image plane.

The PSF grid option in image solution only shows a qualitative results which makes absolute sense for evaluation in preliminary but in the end I cannot validate my results.

or, maybe I missed something in what you wanted to describe.

-Amit

Hi Amit,

Another method you might consider: Define your pixel locations as field points given by Real Image Height. You can use the Field Wizard to set up a grid of points. Then a Standard Spot Diagram will show you the results for each field. Merit function operands can be used to give numerical results. For a system that is aberration limited, spot radius operands such as RSCE can be used. For a nearly diffraction limited system, the DENC operand uses a PSF calculation to compute the distance to a given diffraction encircled energy fraction. Both of these operands accept the field number as an argument.

Kind regards,

David

Hi Amir,

I'm not sure why you feel that the Image Simulation feature is 'qualitative'...can you explain more what your reservations are?

Is your imaging system diffraction-limited? If it isn't, then Geometric Image Analysis is the sequential equivalent of using non-sequential ray tracing and just flooding the system with rays.

Now if your system is diffraction limited, you need to be aware of one of the issues associated with FFT-based PSFs: the image formed is not associated with the image surface directly. Check the Help, under The Analyze Tab (sequential ui mode) > Image Quality Group > PSF > FFT PSF, and the section 'Assumptions Used'.  The PSF is computed on an imaginary plane that is normal to the chief ray, not the image surface. This difference is usually small, but may be important in your case.

I think you would be better served by using Huygens' PSF calculations. The Huygens PSF is computed on an imaginary plane tangent to the image surface at the chief ray intercept. Note the imaginary plane is normal to the normal of the surface, not the chief ray. Therefore, the Huygens PSF accounts for any local tilt in the image surface caused by either the image surface slope, the chief ray incidence angle, or both. Note that the Huygens Image surface is flat, not curved, and it is tangent to the image surface at the location the chief ray strikes.

Again, I'm not sure what your problem with the Image Simulation feature is, but it may be that the Extended Diffraction Image Analysis is better suited to you. It is not useful over an extended field of view, as Image Simulation is, but if you want the PSF at a point over just a few pixels it may be what you want.

- Mark

Hello David,

Your suggestion seems to be really interesting. I will definitely give it a try and let you know if I was successful.

Best regards,

Amit

Hello Mark,

Thank you for the detailed expalanation of things that I was a little ignorant about.

To answer your question about the image simulation, I just was not sure if I will be able to replicate image simulation measurements when I validate my lens design with measurements such as a through focus scan MTF. However, I understand your point and maybe a little more reading up on the image simulation might help me.

if I understand you correctly, as you say:Note that the Huygens Image surface is flat, not curved, and it is tangent to the image surface at the location the chief ray strikes, does that mean that even if my image surface is curved calculating the Huygens PSF will not give me the result that I need?

I will try out the Extended Diffraction Image Analysis and get back to you with the results.

Thanks again for the detailed explanation.

Best regards,

Amit