Patent ID: 9377284
Filing Date: 2016-06-28
CPC Classification: G01B

Claim Text:
1. A metrology apparatus comprising: a body and a member mounted to the body by mechanical bearing assemblies such that the member is rotatable relative to the body about an axis of rotation; a motor for actuating rotation of the member relative to the body about the axis of rotation; wherein a surface sensing device is attachable to the member such that the surface sensing device rotates with the rotation of the member, relative to the body; wherein the motor comprises a magnet and at least one metal coil spaced apart along the axis and mounted such that the magnet and the at least one metal coil are moveable relative to one another; and wherein the motor is arranged such that when it actuates rotation of the member relative to the body, substantially no radial forces from the motor act on the mechanical bearing assemblies such that the location of the axis remains substantially fixed.