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- How to Set the Lens Mount Reference for Thermal Analysis
How to Set the Lens Mount Reference for Thermal Analysis
- By Nam-Hyong Kim
- Published 26 September 2006
- Thermal Analysis
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Changing the mechanical reference of the lens mount
By default, the lens mount contacts the lenses as shown below. The rear surface of the front lens and the front surface of the rear lens physically contact the mount (shaded in green).
The animation below shows how the optics and mount expand and contract with temperature.
Sometimes, the mechnical reference (contact point) between the mount and lens needs to be different. For example, having the mount contact the right surface of the right lens in the layout above. This can be achived by using extra dummy surfaces.
The following animation shows the same system but with the mount contacting the rear-surface of the right lens.
We will demonstrate the method by an example.
Open the attached sample file "rear_mount_sample_1.zmx", available from the last page of this article.
Modify the Lens data Editor as following.
This system models nominal center air gap of 100mm. Notice how the spacer (surface #2) goes all the way to the back of the lens, by its thickness being 140 instead of 100. The dummy propagation on surface #3 needs to be same as the thickness of surface #4 at any temperature; therefore, the TCE of surface #3 has to be the same as the TCE of N-BK7 glass. The TCE of the glass is specified in the glass catalog, and for N-BK7 it is 7.1. Enter this value in the TCE column of surface #3 in the LDE.
Using the Make Thermal tool, create multiple configurations at different temeperatures.
If the temperture of one of the configuration is sufficinetly different than the nominal, the 3D layout will look.
The animation below shows how the optics and mount expand and contract with temperature.
Sometimes, the mechnical reference (contact point) between the mount and lens needs to be different. For example, having the mount contact the right surface of the right lens in the layout above. This can be achived by using extra dummy surfaces.
The following animation shows the same system but with the mount contacting the rear-surface of the right lens.
We will demonstrate the method by an example.
Open the attached sample file "rear_mount_sample_1.zmx", available from the last page of this article.
Modify the Lens data Editor as following.
This system models nominal center air gap of 100mm. Notice how the spacer (surface #2) goes all the way to the back of the lens, by its thickness being 140 instead of 100. The dummy propagation on surface #3 needs to be same as the thickness of surface #4 at any temperature; therefore, the TCE of surface #3 has to be the same as the TCE of N-BK7 glass. The TCE of the glass is specified in the glass catalog, and for N-BK7 it is 7.1. Enter this value in the TCE column of surface #3 in the LDE.
Using the Make Thermal tool, create multiple configurations at different temeperatures.
If the temperture of one of the configuration is sufficinetly different than the nominal, the 3D layout will look.
