Learning Forum

[arezoo.tahmasebi]

Hi everybody,
I have found this definition for source distnace as one of the parameters of ellipse sources on Zemax Documentaion:

The distance along the local z axis from the apparent source point to the location of the source object.
Does anybody know what the apparent source point and the source object are?

[Ethan Keeler]

Hi Arezoo,

Thanks for the question. It might be easier to understand this with a visual example. If the source point is 0, the emitted rays are collimated; however, if the value is positive then the apparent source point is behind the object like shown below:

The distance is simply how far this point is from the source object. If it is positive, it will be behind, and negative means the apparent source point is in front of the source (rays are focusing).

Ethan