In an extrusion force estimation device (1), an oven wall profile acquisition unit (171) measures the unevenness of an inner wall face of a coke oven chamber and acquires the oven wall profile.

In order to create a tangency condition proximate the neck anchor boundary, the parabola used to create the wall profile is angularly offset from the wall profile's axis of rotation.

The respective degrees of operational linearity of the lens sidewall contact angle functions are then evaluated to identify an optimized sidewall profile.

A fluid lens is then constructed by forming the fluid lens reservoir having at least one sidewall with the optimized sidewall profile.

A portion of a parabola is used to define at least part of the revolved wall profile.