Kingsview has added the the Trioptic Optisurf LTM to its metrology tools. It is a non contact method using low coherence interferometry which can achieve accuracy of less than 1 micron. Using this in production combined with CNC lens manufacture the highest accuracy can be achieved routinely for lens thickness.
Trioptic Optisurf LTM
Kingsview non-contact lens thickness measurment