I am looking to replace a lens by a grid phase description of it. However, after several attempts and trials, I am becoming unsure whether it can be done.
Here is the lens I would like to convert into a grid phase : R1=70.9, R2=105.5, thickness=12,5 (all are in mm).
But first, I am trying with a simple convex-plane lens : R1=100, R2=Infinity, thickness=12.5 (all are in mm).
It seems that whether I have 10 or 20 or 50mm of glass after the curve doesn’t matter in the phase description, because it only adds a phase offset in a uniform manner on the grid, and it seems that Zemax interprets these 3 different grids identically. To sum up, 3 different lens are represented identically by a single grid phase, because only an offset differentiates them.
However, when I simulate a change of thickness using traditional methods in Zemax, there is a difference between these 3 lenses, for example the amount of spherical aberration.
I have read across other topics that the phase sag should be defined through phase, dphase/dx, etc, however I have only implemented phase.
My interrogations are the following :
- Is it possible to represent a lens entirely through phase in Zemax ?
- If so, is it really necessary to implement dphase/dx, d^2(phase)/dx^2, etc in addition to phase ? If so, why, since I would extract these values from the sole phase shape, why wouldn’t Zemax do it itself ?
- What should I measure to check the grid phase represents a lens identically ? Because the grid phase is a thickness=0 plane, the positions of other elements in the system are altered compared to the classical representation ; and the values given by Zemax for effective focal length in the grid phase configuration aren’t right ; and it doesn’t plot aberrations (Seidel Diagram) in the grid phase case either.
If you need any more information do not hesitate to ask, I will provide for them, if that helps you help me!
Best answer by MichaelHView original