Abstract: A rotation detection kit, comprising: a beam source; a receiver comprising at least one beam intensity sensor; a polariser device for location in the path of a beam emitted from the beam source and received by the beam sensor; and a modulator. The modulator is configured to modulate at least one of i) the beam source and ii) a beam emitted by the beam source to create a discretely varying polarisation orientation thereby defining first and at least second temporally spaced beam portions. The temporally spaced beam portions are incident on the polariser device and the beam sensor and have substantially identical profiles and at least an initial common propagation axis toward the polariser device.

Abstract: Apparatus for measuring displacement between two members. A scale is provided on one member and has an incremental pattern with at least one reference mark embedded in it. A read head is provided on the other member and comprises a periodic diffraction means for interacting with a light pattern modulated by the incremental pattern on the scale to produce interference fringes having movement relative to said readhead responsive to said displacement, first detecting means for detecting the movement of the interference fringes, imaging means for imaging the reference mark and second detecting means for detecting the image of the reference mark.

Abstract: A method of calibrating an articulating probe head comprising the steps of measuring an artefact of known dimensions with the workpiece sensing probe mounted on the articulating probe head, in which the articulating probe head is unlocked. An error functional map is generated corresponding to the difference between the measured and known dimensions of the artefact. Subsequent workpieces are measured with the articulating probe head unlocked and the corresponding correction applied. The true dimensions of the artefact may be determined by measuring it with a probe mounted on an articulating probe head in which the axes of the articulating probe head are locked. A mechanical lock is provided to lock the axes of the articulating probe head.

Abstract: A pivot joint assembly is described that includes a multi-axis revolute joint portion and a ball joint portion. The multi-axis revolute joint portion provides rotational movement about two or more revolute axes that substantially intersecting at an intersection point. The ball joint portion comprising a ball located in the vicinity of said intersection point. The pivot joint assembly allows separate coupling of load members and metrology members to one or more platforms. A hexapod co-ordinate measuring machine including such pivot joint assemblies is also described.

Abstract: A pivot joint has a first member having a ball located at one end, a fixed member having one or more bearing surface, which locates on the ball of the first member and a second member having one or more bearing surface located at one end which locates onto the ball of the first member. The first and second members are rotatable about the centre of the ball. This type of pivot joint is suitable for use in a machine such as a Stewart platform.

Abstract: A rotary gas bearing is described that comprises a first part rotatable relative to a second part. The first part comprises a support member and a first portion and a second portion attached to the support member. The first portion comprises a first bearing surface and the second portion comprising a second bearing surface. Both the first portion and the second portion are attached to the support member by screw thread connections. The second part may comprise complimentary bearing surfaces. Epoxy may be used to fix the first and/or second portions to the support member. A method of determining the bearing working gap by measuring gas flow through the bearing is also described.

Abstract: An optical element has a member having features which interact with incident light to produce two or more resultant beams. The configuration of the optical element is such that light which interacts with said features when passing through the member from a first side to produce two or more resultant beams does not interact with said features when returned to another side of the member and/or vice versa. The optical element may be used in a readhead of a scale and readhead apparatus.

Abstract: A pivot joint has a first structure comprising a ball mounted in a receptacle, wherein the location of the ball is held with respect to the receptacle, and a second structure mounted on and movable with respect to the ball, wherein the second structure has at least one bearing surface which defines its position with respect to the ball. The ball may be held in location by contact with the receptacle at least two positions. At least one of the positions of contact may be adjustable.

Abstract: Position measurement apparatus, such as hexapod co-ordinate measuring machine, is described that comprises a thrust frame and a metrology frame. The thrust frame comprises a load carrying base connected to a moveable platform by a plurality of powered extendable legs. The metrology frame comprising a metrology base attached to the load carrying base by a base attachment mechanism such as kinematic mounts. The base attachment mechanism is arranged to prevent any distortions of the load carrying base being transmitted to the metrology base.

Abstract: A probe for position determining apparatus has a probe body (18) and a workpiece-contacting stylus (14). A strain sensitive structure connects the probe body and the stylus, and includes bendable members (32). The bendable members have an asymmetric cross-section, e.g. “T” shaped. A strain gauge (33) is mounted to the stem of the “T” to detect the bending caused when the stylus contacts a workpiece. This enables the strain sensitive structure to be both robust and sensitive to the bending.

Abstract: A tool shank (18;38;138) is described that comprises a spindle attachment portion (20) that is removably attachable to the rotatable spindle (12) of a machine tool (10), a shank body portion (21;121) which extends beyond the end of the spindle when the tool shank (18;38;138) is attached to the spindle (12) of a machine tool (10) and the first part (26;38;148) of a separable electrical coupling (22;132). The shank body portion comprises a feature (28;128) suitable for engagement with a tool change device (29) and the first part (26;38;148) of the separable electrical coupling (22;132) is located on the shank body portion (21;121) between the feature (28;128) and the spindle attachment portion (20). A machine tool (10), and a kit for retrofitting a machine tool (10), that comprise the second part (24;148) of the separable electrical coupling (22;132) are also described.

Abstract: An extendable leg assembly for a measuring machine, such as a co-ordinate measuring machine, is described. The extendable leg assembly has a first end and a second end and comprises metrology apparatus for measuring the separation between the first end and the second end. The metrology apparatus comprises one or more elongate metrology members having a low coefficient of thermal expansion. The extendable leg assembly may be attached to one or more platforms by a pivot joint.

Abstract: A method of calibrating an articulating probe head comprising the steps of measuring an artefact of known dimensions with the workpiece sensing probe mounted on the articulating probe head, in which the articulating probe head is unlocked. An error functional map is generated corresponding to the difference between the measured and known dimensions of the artefact. Subsequent workpieces are measured with the articulating probe head unlocked and the corresponding correction applied. The true dimensions of the artefact may be determined by measuring it with a probe mounted on an articulating probe head in which the axes of the articulating probe head are locked. A mechanical lock is provided to lock the axes of the articulating probe head.

Abstract: A pivot joint has a first structure comprising a ball mounted in a receptacle, wherein the location of the ball is held with respect to the receptacle, and a second structure mounted on and movable with respect to the ball, wherein the second structure has at least one bearing surface which defines its position with respect to the ball. The ball may be held in location by contact with the receptacle at least two positions. At least one of the positions of contact may be adjustable.

Abstract: Methods are described for calibrating a turning machine having a first rotatable portion or chuck for holding a workpiece. The first rotatable portion has a first feature associated therewith. The method comprises the steps of using a measurement probe to determine the position of the first feature, rotating the first rotatable portion through an angle, and using said measurement probe to determine the new position of the first feature. The extension of the technique to swivel head mill-turn machines is also described.

Abstract: Apparatus and method for making a metrological scale by electrochemical machining of a scale substrate using a tool having at least one feature. The method has the steps of passing an electrolyte solution between the tool and the scale substrate and forming an electrical connection between the scale substrate and the tool. Electrochemical dissolution of the scale substrate occurs adjacent to the feature of the tool to produce at least one scale marking. This is suitable for making linear, rotary and two dimensional scales.

Abstract: A tool shank (18;38;138) is described that comprises a spindle attachment portion (20) that is removably attachable to the rotatable spindle (12) of a machine tool (10), a shank body portion (21;121) which extends beyond the end of the spindle when the tool shank (18;38;138) is attached to the spindle (12) of a machine tool (10) and the first part (26;38;148) of a separable electrical coupling (22;132). The shank body portion comprises a feature (28;128) suitable for engagement with a tool change device (29) and the first part (26;38;148) of the separable electrical coupling (22;132) is located on the shank body portion (21;121) between the feature (28;128) and the spindle attachment portion (20). A machine tool (10), and a kit for retrofitting a machine tool (10), that comprise the second part (24;148) of the separable electrical coupling (22;132) are also described.

Abstract: A metrology instrument, such as a probe, probe head, stylus or stylus arm, for mounting on a coordinate position apparatus. The metrology instrument is at least partially constructed from at least one sheet of thermally stable metallic material which is folded to form a three dimensional structure. The at least one sheet of thermally stable material is utilized in the metrology loop of the metrology instrument.

Abstract: The present invention relates to an apparatus for the manufacture of a metrological scale comprises a scale substrate (18), at least one laser (20) for producing scale markings on the scale substrate (18), a sensor (30) to detect the depth of the scale markings produced on the scale substrate (18), and a feedback system which uses data from the sensor (30) to adjust parameters of the system to produce scale markings with the desired depth.

Abstract: Disclosed is a scanner for the scanning of articles including a scanning apparatus (10) having a scanning device (18) and a rotatable sample mount (14,420) whereby, the scanning device and mount are relatively displaceable along the rotary axis (48) of the mount, a receptacle (40,140,240,400) mounted on the sample mount, the receptacle being capable of securely accommodating an article (30), and an actuator (146,246) for linearly displacing the receptacle whereby, actuation of the actuator displaces the receptacle and any article secured thereto, with respect to the sample mount. The article may be elongate and the displacement by the actuator is along an axis defined by the elongate axis of the elongate article. Also disclosed is a method of scanning.