Means for in-place automated calibration of optically-based thickness sensor

摘要

The calibration of a laser caliber is described. The laser caliber uses first and second sensors to determine the distance to different sides of a sheet. A third sensor is used to determine the distance between the first and second sensors. The calibration of the first, second, and third sensors is done by positioning a test object onto the platform sensed by the third sensor. The platform is moved to multiple positions in order to calibrate the first, second and third sensors. Since the displacement of the platform moves the distance to the target of the first, second and third sensors the same amount, the sensors can be accurately calibrated for a number of different positions of the test object. A very accurate calibrating displacement measuring device such as an LVDT can be used.