Renishaw Plc

Michael Homer

James Reynolds Henshaw

Alan James Holloway

Iain Robert Gordon-Ingram

Peter Geoffrey Holden

A measurement scale () is movable in plane x relative to a mask () and photodetector (). When a pattern of apertures in the mask () are in correlation with a pattern of apertures e.g. a reference mark in the scale () then light bands a b and c may propagate to the detector (). The relative sizes of the patterns is such that the light bands converge at the detector (). Other embodiments show light divergent and light inversion correlation of incongruent patterns.

Position determination system for determining the position of one relatively moveable part relative to another relatively movable part

A scale ( ) is illuminated by a light source ( ). After interaction with an index grating ( ), fringes (F) are formed in a Talbot plane and analyzed by an analyzer grating ( ). To decrease the sensitivity to changes in the ride height of the index grating above the scale, the light source is restricted to a small but finite size, and positioned so that it subtends a small angle &Oslash; at the analyzer grating (or, if a collimating lens ( ) is used, positioned so that it subtends a small angle &Oslash; at the lens). The size of the light source should preferably be smaller than a predetermined value such that the extent of a geometric fringe visibility envelope exceeds the extent of a Talbot fringe visibility envelope.

Opto-electronic scale reading apparatus

A length of scale ( ) which has a profile consisting of a sequence of troughs ( ) and crests ( ) is subjected to a process to make the shapes of the crests more regular, thus increasing and making more predictable the signal reflected from the crests on the scale. The process comprises passing a length of scale ( ) between upper ( ) and lower ( ) cylindrical rollers. The lower roller ( ) may be driven or the length of scale ( ) may be pulled through. Reference marks or identification marks may be added to the scale by appropriately marking the upper roller ( ). Alternatively, the marks may be added at an initial embossing step which imparts the troughs and crests profile to the scale or at a separate subsequent step.

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Dursley, United Kingdom

Michael Homer