Remove the default boundary constraints by rebuilding the default merit function with the glass boundary constraints de-selected:

We will instead use the “full thickness” boundary constraint operands FTGT (Full Thickness Greater Than) and FTLT (Full Thickness Less Than). Unlike the default boundary constraint operands, the FTGT/FTLT operands measure the thickness of a surface at 200 points between the vertex and the edge along the +y radial direction.

For our FTLT and FTGT operands, we will use the same thickness constraints as we used for the default boundary constraints (minimum thickness of 1 mm and maximum thickness of 5 mm). Set the weight of both operands to 10. Here is the merit function with the FTLT and FTGT operands added:

The value and contribution of the FTGT operand is indicative of what we already know; the thickness of the lens is too thin at intermediate locations. The value of the FTGT operand indicates that the thinnest part of the lens is only 0.4079 mm thick.

We can now optimize the system with the improved boundary constraints in place. Click on the “Opt” button in the button bar and select “Automatic” optimization. The results are encouraging. The thickness of the lens has increased noticeably at the intermediate locations:

The active cursor in the layout as well as the value of the FTGT operand in the merit function both indicate that the intermediate thickness values are still less than 1 mm. The value of the FTGT operand indicates that the thinnest part of the lens is 0.8265 mm thick. Increasing the target and/or the weight of the FTGT operand and re-optimizing will increase the thickness further.