The Rank Organisation Plc

David J Whitehouse

John Jungles

Eric Gordon Nightingale

Harish C Sharma

A method of determining the coordinates of the center of curvature of the curved surface of a workpiece with respect to a predetermined frame of reference the origin of which coincides with the center of relative rotation between the workpiece and a sensor of a surface measurement instrument. The method requires sensor signals to be derived at only three points along the traverse of the sensor and there are no constraints on the position or symmetry of the three points thereby allowing the method to be used on workpieces having only a partial arc. Two output signals representing the x and y coordinates of the center are produced from signals representing the angular position of the three points and from the sensor signals at the said three points.

Method of determining the coordinates of the center of curvature of the

A method of deriving the value of any one of the commonly used parameters for characterizing surfaces in surface measurement technology includes the steps of computing the autocorrelation function of a signal representing the surface, and selectively utilizing values of this autocorrelation function together with the value of the sampling interval used in generating the autocorrelation function, to derive the desired parameter values. This method considerably simplifies the information on a surface which is required, and enables micro-processor techniques to be used in the computation of the parameters.

Testing apparatus

An optical sensing instrument for detecting specular and/or non-specular reflections of light from a surface under test has a sensor head with a plane face having a semi-circular recess in which are housed a plurality of light sources and a plurality of photodetectors each having an associated lens, the optical axis of which passes through the center of curvature of the semi-circular recess. The photodetectors and the light sources are positioned such that respective source/detector pairs are located on optical axes which form mirror angles with respect to the axis of symmetry of the sensing head. Means are provided for simultaneously energizing one or more selected light sources and one or more of the photodetectors.

Measuring instruments

A surface measurement apparatus of the type in which a sensor is traversed along a path in contact with or adjacent the surface of a component under test. The sensor has three or more transducers which, in the described embodiment, physically contact the surface under test and produce individual signals as they are traversed along the same path over the surface of the component under test. The signals produced by the transducers are amplified and combined in such a way that the composite signal so produced is not dependent on any variation in the position of the body of the transducers as the device is traversed along the surface of the component under test thereby allowing the use of sensors which are not mounted on accurately preformed datum-determining mounts such as a flat bed or an accurate spindle.

Measuring instrument

An optical diffractometer is disclosed in which there is provided a television camera system for displaying light patterns derived from the image plane or the transform plane of the diffractometer. The camera system includes a modulating network for providing a pseudo three dimensional display by mixing signals from the X ramp and Y ramp generators together and by mixing the signal from the Y ramp generator with a signal representative of the television camera beam current. The mixed signals are applied to the X and Y plates of a cathode ray tube to provide a display of the signals.

Growing community of inventors

Melton Mowbray, United Kingdom

David J Whitehouse