Manual linear stages

- Nov 20, 2017-

 In manual linear stages, a control knob attached to a lead screw is typically used. The knob may be indexed to indicate its angular position. The linear displacement of the stage is related to the angular displacement of the knob by the lead screw pitch. For example if the lead screw pitch is 0.5 mm then one full revolution of the knob will move the stage platform 0.5 mm relative to the stage base. If the knob has 50 index marks around its circumference, then each index division is equivalent to 0.01 mm of linear motion of the stage platform.

 Precision stages such as those used for optics do not use a lead screw, but instead use a fine-pitch screw or a micrometer which presses on a hardened metal pad on the stage platform. Rotating the screw or micrometer pushes the platform forward. A spring provides restoring force to keep the platform in contact with the actuator. This provides more precise motion of the stage. Stages designed to be mounted vertically use a slightly different arrangement, where the actuator is attached to the movable platform and its tip rests on a metal pad on the fixed base. This allows the weight of the platform and its load to be supported by the actuator rather than the spring.