Thermal analysis - - How thermal parameter values being calculated?

Question

I want to know the detail about how thermal pick up values being calculatedin in multi-configuration editor for coefficients of even asphere surface.
The surface sag is given by:

I can find related information from helpfile:

Values in multi-configuration shown as below, surface 7 is even asphere surface, TCE for surf7&#160;is 8, TEMP for configuration 1,2, 3 is 20, 60, 100, respectively. The first configuration is the nominal configuration:

How thermal pickup values being calculated?&#160;

Julia · Accepted Answer

Answer:For coefficients of Even Asphere surface,&#160; a1, a2, a3… they have different units, and shown as below in case of lens units was mm&#160; :a1,&#160; units was 1/mma2,&#160; units was 1/mm^3a3,&#160; units was 1/mm^5……So the scaling for above parameters was &#160;1/r, 1/r^3, 1/r^5 ….The TCE value is the thermal coefficient of expansion in 1e-6/K. We know that TCE=8, and&#160;δT=40 K.&#160;a1=a2=a3=p=100Radius of surface7 is 100.For configuration2:radius= 100+100*8*40*e-6= 100.032crvt= 1/100.032= 9.996801024E-03&#160;a1= p/(scale of r) =&#160; p/(100.032/100)= 0.9996810 pa2=p/scale of (r^3)= p/ (100.032^3/100^3)= 0.99904614 pa3=p/ scale of (r^5))=p/(100.032^5/100^5)=&#160; 0.99840153 pFor configuration3:radius= 100+100*8*80*e-6= 100.064crvt= 1/100.064= 9.993604093E-03&#160;a1= p/(scale of r) =&#160; p/(100.064/100)= 0.9993604093&#160;pa2=p/scale of (r^3)= p/ (100.064^3/100^3)= 0.998082455 pa3=p/ scale of (r^5))=p/(100.064^5/100^5)=&#160; 0.9968061348 p

bhousand · Answer

Thermal formulaWhat&rsquo;s the equation for surface shape versus temperature in a sequential code? As it turns out, the equation is in the attached pdf with an explination, it is derived from the realization that the part expands and contracts, while the coordinate system does not. Not sure if this was published by anybody, I worked it out myself in 1986.-Brien Housand, 05/01/2020

Thermal analysis - - How thermal parameter values being calculated?

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