A linear stage or translation stage is a component of a precise motion system used to restrict an object to a single axis of motion. The term linear slide is often used interchangeably with "linear stage", though technically "linear slide" refers to a linear motion bearing, which is only a component of a linear stage. All linear stages consist of a platform and a base, joined by some form of guide or linear bearing in such a way that the platform is restricted to linear motion with respect to the base. In common usage, the term linear stage may or may not also include the mechanism by which the position of the platform is controlled relative to the base. Principle of operation In three-dimensional space, an object may either rotate about, or translate along any of three axes. Thus the object is said to have six degrees of freedom (3 rotational and 3 translational). A linear stage exhibits only one degree of freedom (translation along one axis). In other words, linear stages operate by physically restricting 3 axes of rotation and 2 axes of translation thus allowing for motion on only one translational axis. Guide types Linear stages consist of a platform that moves relative to a base. The platform and base are joined by some form of guide which restricts motion of the platform to only one dimension. A variety of different styles of guides are used, each with benefits and drawbacks making each guide type more appropriate for some applications than for others. Rollers Benefits Inexpensive. Drawbacks low load capacity, poor accuracy, short lifetime. Applications Optics lab stages, drawer slides. Recirculating ball bearing Benefits Unlimited travel, relatively inexpensive. Drawbacks Low load capacity, quick to wear, oscillating positioning load as bearings recirculate. Applications Flexure Benefits Excellent accuracy, no backlash, no wear (infinite lifetime). Drawbacks Short travel (limited by flexure range), low load capacity, expensive. Applications Optic fiber alignment. Cylindrical sleeve Benefits High load capacity, unlimited travel, inexpensive. Drawbacks Susceptible to binding if bending moments are present. Applications Radial arm saws, scanners, printers. Dovetail Benefits Highest load capacity, unlimited travel, long lifetime, inexpensive. Drawbacks High positioning force required, susceptible to binding if bending moments are present, high backlash. Applications Machine shop equipment (ex. mill and lathe tables). Position control methods The position of the moving platform relative to the fixed base is typically controlled by a linear actuator of some