Infinity

The reference to "Infinity" makes the assumption that the exit pupil is very far away and that the OPD correction term is given strictly by the angular error in the ray.

For focal systems (where option Afocal Image Space is unchecked), the OPD is the difference of optical path lengths up to the image plane between the ray being considered and the chief ray, minus a correction term. The correction term is defined as below:

If OPTH is the Optical Path Length, then OPD can be simply written as:

OPD = OPTH (Surf=Image Plane, Wave,Hx,Hy,Px,Py) – OPTH(Surf=Image Plane, Wave,Hx,Hy,0,0) - Delta.

This setting should only be used if OpticStudio is unable to correctly compute the effective exit pupil location and size. This can occur with some very unusual optics which do not form images (real or virtual) of the stop surface, or for some non-axial systems where the computed exit pupil lies too close to the image surface for the exit pupil correction to be accurate. Do not use the Infinity reference unless there is compelling reason to believe that the exit pupil computation is not correct.

This settings can also be used when working on coherent effects from multiple rays at the chief ray point. This OPD calculation sets all the phase values to be appropriate for passing through that one point.

Note that for afocal systems (where option Afocal Image Space is checked), this option has no effect. The OPD calculation will be equivalent to setting the Reference OPD to Exit Pupil.

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• Absolute/Absolute 2