+1Hi,
I downloaded a simple lens (LA7270-E4, Thorlabs) zemax files, and I don’t understand the focal plane and principle plane locations in image space as shown in the prescription, I think they are opposite.
Image attached. Please let me know your thoughts.
Thanks,
Ying
Best answer by David.Nguyen
Hi Ying,
I think the answer might be written in the description below CARDINAL POINTS. It says:
Image space positions are measured with respect to the image surface.
This means the focal plane is pretty much (0.079572 lens units away) located at the image surface and the principal plane is about 500 lens units back, which is more or less where the lens is, and where I would assume the principal plane to be also.
Does that make sense?
Take care,
David
+2Hi Ying,
I think the answer might be written in the description below CARDINAL POINTS. It says:
Image space positions are measured with respect to the image surface.
This means the focal plane is pretty much (0.079572 lens units away) located at the image surface and the principal plane is about 500 lens units back, which is more or less where the lens is, and where I would assume the principal plane to be also.
Does that make sense?
Take care,
David
+1
Hi David,
Yes, you are absolutely correct.
Thanks,
Ying
Hi Ying,
There is a the Cardinal Point function located in Analyze > Ray & Spots > Cardinal Points.
It tells the same information shown in the prescription data, but in cardinal points you can decide the first and last surface. It makes it easier to look for specific principal planes in your system if you have a single or multiple lens. I attached an image of the cardinal points for a F=50mm doublet as an example.
Best,
Ian
+1Hi Ian,
This is very helpful!
Thanks,
Ying
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