The VE series Gap Detector is the sensor which can measure the gap, but you can also measure the thickness using two VE sensors.

 

Arrange the target measurement object in between VE sensor A and B as shown in following figure. Two VE sensors are measuring the gap between the target measuring object (Ga, Gb). if you specify the space between these two sensors (GS), you can obtain the thickness of the target measurement object (t).

 

Moreover, you can obtain the distance between two VE sensors by measuring the gap value with the master piece.

 

For farther information, please refer to the "Why do they need the master piece calibration during the thickness measurement of conductor and semiconductor by Non-contact Thickness/Displacement Meter?".