Z axis laser focusing control

[da21]

Hi , has anyone added or could give further info on interfacing a Linear displacement transducer ( LVDT ) , we have a laser we are retrofitting to Mach3
which has a Foot fitted with an LVDT , to track the Z axis height over a distance of 2.5mm , used for keeping the lens focused etc , how can we incorporate this function , or will it need a plugin etc ,

Any help appriciated

Dave