Hi @Shivam,
Where have you placed your stop in the example provided?
What is the purpose of the paraxial lens after L3?
What is the threshold value for too much distortion? In your second example, it is only 0.005%.
How are you supposed to vary the distances between L1, L2, and L3?
Hi @Michael.Young ,
The stop is placed in the object space, before the lens 1.
The paraxial lens after L3 is representing as eye lens. We are assuming that rays coming out from the L3 lens will fall into the eye lens and converge on retina.
The distortion shown in the zemax is very less but in reality when seeing from this setup of lenses, only the center portion is clear, the edges seem to be distorted in a great amount. This is the observation from a human eye from seeing through these three lenses.
Lens 3 (which is closer to the eye or paraxial lens in this case) is fixed and distance between lense 3 & L2 is increased & then distance between L2 & L1 is changed. This is to note that L3 is closer to the eye and hence it is fixed. Lens 2 & 1 is moved.
Hi @Shivam,
I would like to follow up on your problem to see how things are going.
Originally, the question sounded like it was a homework assignment that was intended to demonstrate the methods to reduce the 3rd-order aberration of distortion (W400). However, given your comment about the image not being clear towards the edges, makes me think that may not have been the intent of the original question.
To reduce 3rd-order distortion, symmetry about the stop is the most straightforward way doing so. This means the stop should be placed near or inside of the biconvex lens. To control distortion, the DIST operand can be used.
To control for “clarity” or contrast/resolution. Use the default merit function to build the merit function and use the spot optimization at this point.
Perhaps these resources may shed some light on the design process,
https://support.zemax.com/hc/en-us/articles/1500005576302-How-to-design-a-singlet-lens-Part-1-Setup
https://support.zemax.com/hc/en-us/articles/1500005577942-How-to-design-a-singlet-lens-Part-2-Analysis
https://support.zemax.com/hc/en-us/articles/1500005577962-How-to-design-a-singlet-lens-Part-3-Optimization
