TEDX, TEDY, TEDR: Tolerance on Element Decenters
TEDX, TEDY and TEDR are used to analyze the decentration of a lens group in X, Y, or a random radial direction respectively. Int1 (Surf1) and Int2 (Surf2) indicate the first and last surfaces of a lens group or element. Min and Max specify the minimum and maximum decentration in lens units.
For TEDR, both Min and Max must be greater than or equal to 0.
Decentration is achieved by inserting a pair of coordinate breaks around the surfaces contained by Surf1 and Surf2 and decentering the entire group as a unit. For this reason, these operands generally should not be used on either side of an existing coordinate break.
For the tolerancing of a single surface of any type, set Surf1 and Surf2 to the same surface number. For single Standard surfaces the TSDX, TSDY, TSDR operands can also be used.
These operands may be nested. Nesting rules are fully described in the section Nesting rules for Monte Carlo analysis.
The TEDR radial decenter operand is recommended for systems with circular optics and circular mounts such as traditional camera lenses or microscope objectives. TEDX and TEDY Cartesian decenter operands are recommended either for anamorphic systems with a decoupled X and Y optical axis or for systems with rectangular optics and rectangular mounts. If Cartesian decenter operands are used with circular optics and circular mounts, there will be a higher probability the decenters will tend towards the 45° diagonals between the X and Y axis, possibly leading to skewed tolerancing results.
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