US 5,341,702 AGranted

Apparatus for calibration of an angular displacement

AssigneeRenishaw Transducer Systems Limited

InventorsRaymond J. Chaney, Jeffrey Graham

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Abstract

A system for calibrating a rotary table (10) includes an indexing table (20) (which is a Hirth coupling table) and an angular interferometer (100), together with a control (200). The indexing table is mechanically coupled to the rotary table (this being the only connection between the rotary table to be calibrated and the calibration system), and the interferometer is set up to measure rotation of the indexing table. During rotation of the rotary table (10) to a target angle, the control (200) monitors the interferometer reading, and when this reading exceeds a predetermined threshold, actuates a drive motor (240) of the table (20) to counter rotate the table, thereby to maintain the optics (106) of the interferometer in alignment with the laser beams (L2, L3) and thus enable continuous measurement of the position of the indexing table.

Claims7

Dependent claims

Apparatus for measuring angular displacement of a support mounted for rotation relative to a base of a rotary table, the apparatus comprising:

an indexing table including a stator which, in use, is mounted to the support of the rotary table, and a rotor rotatable relative to the stator between a plurality of discrete angular rest positions;
an angular interferometer for measuring angular displacement of said rotor of said indexing table;
a motor provided on said indexing table for rotating said rotor relative to said stator in response to a control signal;
and
a control for;
(a) receiving a value of angular displacement from said interferometer;
(b) determining whether said value is equal to or exceeds a predetermined threshold value;
and
(c) generating said control signal in response to said value equalling or exceeding said predetermined threshold value to cause said motor to counter-rotate said rotor.

6 more elements

Dependencies are inferred from the claim text.