Why should the scale handwheel be in one direction?
Avoiding the return difference. A way of reducing errors.
Hand wheel connection is mostly turbine, gear. In reverse rotation, due to the gap (also known as backlash) reasons, will lead to reversal when there is a part of the actuator does not move, resulting in inaccurate calibration
In the physics experiment instrument, the gap in the gear structure (or thread) causes the displacement to be stable in the course of moving along the one-way direction. If the displacement is transferred to the other side first, and then to the other side, when the middle direction changes, the power tooth will appear a little idle due to the existence of the backlash. Since the power teeth are often connected to the scale of our reading mechanism, the readings change when idling, but the actual instrument measurement status has not changed, which is the null path difference.Therefore, when measuring the length of the He-Ne laser beam, the micro handwheel can only rotate in one direction, so as to avoid the error of the gap.
