| kimclps |
2011-03-27 13:10 |
Zemax裏的說明，Grid Distortion不適用於field為real image height及半視場角>=90度的情形。 U J uz
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ZEMAX cannot compute the distortion in the manner described here if the field type is real image height. The reason is that when using real image height, ZEMAX iterates each ray trace to find the exact field coordinate to hit the desired image coordinate; implicitly removing the distortion. As a workaround, ZEMAX automatically changes the field type from real to paraxial image height for the purposes of this computation. This change is significant if the distortion is large. Note the value for "Field Width" will then be in units of paraxial image height rather than real image height. VFK]{!C_
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Grid distortion can not be calculated if the field units are angles and the maximum angle equals or exceeds 90 degrees. This limitation is due to the assumption that the predicted image height is proportional to the tangent of the field angle in object space. When the field angle exceeds 90 degrees, the tangent does not predict the linear image height correctly. `Bb32L
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