The BBP series of air-extended, spring-loaded linear variable displacement transducer position sensors features a probe that moves out and makes measurements only near the end...
EAZY-CAL LVC 4000 signal conditioner with analog (4-20 mA or user-selectable voltage) and RS-485 outputs is compatible with most LVDT and RVDT linear position sensors.
LVDTs have a spring-loaded shaft running in a precision sleeve bearing and connected to the core of an LVDT. Measurement repeatability is 0.6 µm or better.