Abstract: A measuring probe includes a suspension module 112 in which a stylus holder 140 is suspended from a housing on a pair of diaphragms 142,144. At least one of the diaphragms is formed with spiral cut-outs whereby the stylus, which is connected at the center of the diaphragms, is able to move transversely of the axis of the housing as the stylus holder pivots when transverse forces are applied to the stylus tip. A transducer module 110 is releasably supported on the suspension module by a kinematic mounting 116,118 and is retained in position by magnets 120. The transducer module contains optical transducers 200,210,220 for measuring the deflection of the stylus.

Abstract: A method of calibrating a scanning system comprising a machine and a measuring probe, includes the steps of error mapping the system statically and qualifying the stylus tip so that the system will provide accurate measurements, determining the positions of a number of datum points on the surface of an artefact with the probe stylus in contact with the workpiece and at zero deflection normal to the surface, scanning the surface through the datum points at a nominal stylus deflection and at the maximum speed which provides repeatable position measurements to make a second determination of the positions of the datum points, determining the errors attributable to the scanning process by subtracting the positions obtained in the first and second determinations, and storing the error values for correction of subsequent measurements of similar artefacts.

Abstract: A rotary ring 3 for use in scale reading apparatus has a scale on its outer circumference and is mounted on a rotary shaft 6. To reduce error caused by the rotary ring 3 not sitting concentrically on the rotary shaft 6, the inner circumference 5 of the rotary ring 3 and the outer circumference of the shaft 6 are both tapered. To compensate for eccentricity of the shaft, mounting screws 8 are provided in holes on the rotary ring to adjust the position of the rotary ring until it is concentric with the axis of rotation of the shaft.

Abstract: A scale and scale reader are disclosed for measuring displacement in two directions. One embodiment of the scale shows a chequered pattern forming a matrix of marks for providing a light pattern to a diffraction grating. The diffraction grating has a similar chequered pattern and provides an interference light pattern to a photodetector array. The interference pattern enables the detector to determine movement in each of the two directions.

Abstract: A beam deflector has first and second wedge prisms having refractive indices and geometries which are similar (in the case of the geometry to within arc minutes). The prisms are rotatable about an optical axis O defined by the direction of propagation of the incident light beam, to adjust the angle through which the incident beam is deflected. A third prism has a wedge angle which is greater than that of the first and second prisms by a factor of 2. When the directions in which the first and second prisms refract the beam away from the optical axis are aligned about the optical axis at notional angles of 0° and 90° respectively, and the third prism is aligned with its direction of refractive deviation at a notional angle of 225° about the optical axis, the light beam will pass undeviated through the deflecting device.

Abstract: A probe arm for locating a probe on a machine includes a signal conditioning circuit which produces probe status signals to be sent to the machine. The signal conditioning circuit includes two LEDs mounted on the arm and which are differently coloured to provide a visual indication of probe status e.g. probe ready or probe triggered. One of the LEDs has twice the efficiency of the other and therefore to maintain consistent illumination one is driven with twice the current of the other. Thus by monitoring the current through the LEDs in a sensing circuit at the output terminals of the signal conditioning circuit the status of the probe is communicated to the machine. Power to the probe and signal conditioning circuit is provided from the machine via the output terminals so that only two wires are required to connect the arm to the machine.

Abstract: A tiltable table 10 is shown having (in this embodiment) two tilt positions to which top 20, and base 30 are repeatably repositionable. Support parts 32, 34, 36 and 38 provide a kinematic support in both of the two positions. Further embodiments provide more than two tilt positions. Positions are held by means of magnetic attraction, here, magnets, 40 and 42.

Abstract: A coordinate measurement machine 10 has a movable head 20. A probe 12 and arm 14 are attached via a disconnectable joint to the head. An exchange rack 30 is provided for exchanging one probe/arm, for another. A plate 50 acts to disconnect and reconnect the joint and also to support the probe/arm whilst disconnected. Plate 50 actuates a toggle mechanism 42 when the head is moved relative to the plate and causes a plunger 26 to engage/disengage with a peg 24 thereby securing or releasing the joint during the said movement.

Abstract: The component parts of an optical measuring system include two housings (20,22) each of which contains optical elements of the system, and a base (10). The two housings are each provided on at least one face with the complementary parts of a kinematic support (18), and the optical components are arranged within the respective housings so that when the kinematic support is engaged the optical components are properly aligned. The base is provided with a kinematic support (16) on its surface which is arranged so that when the base is aligned with a machine axis, any housing placed on the kinematic support will automatically be aligned with the machine axis. Thus by aligning the base with a machine axis, the optical components of the system will automatically be aligned when the housings are connected to the base and to each other using the kinematic supports.

Abstract: A measuring probe includes a suspension module 112 in which a stylus holder 140 is suspended from a housing on a pair of diaphragms 142, 144. At least one of the diaphragms is formed with spiral cut-outs whereby the stylus, which is connected at the centre of the diaphragms, is able to move transversely of the axis of the housing as the stylus holder pivots when transverse forces are applied to the stylus tip. A transducer module 110 is releasably supported on the suspension module by a kinematic mounting 116, 118 and is retained in position by magnets 120. The transducer module contains optical transducers 200, 210, 220 for measuring the deflection of the stylus.

Abstract: A coordinate measuring machine (CMM) carries a probe and is controlled by a controller to drive the probe to take measurements on a workpiece. In order to reduce the effects of acceleration-induced deflections of the probe on the measurements made by the machine, accelerometers are provided to measure the accelerations of the probe and to produce signals indicative thereof. The acceleration signals (45) are passed to the controller (FIG. 2) where they are integrated (46) and filtered (48) before being passed as velocity signals (49) to a summing junction (50) from which they are fed to a velocity feedback control loop[ (34, 35, 36, 37) which reduces any changes in the velocity (and hence deflection) of the probe due to the accelerations.

Abstract: A coordinate measuring machine (CMM) carries a probe and is controlled by a controller to drive the probe to take measurements on a workpiece. In order to reduce the effects of acceleration-induced deflections of the probe on the measurements made by the machine, accelerometers are provided to measure the accelerations of the probe and to produce signals indicative thereof. The acceleration signals (45) are passed to the controller (FIG. 2) where they are integrated (46) and filtered (48) before being passed as velocity signals (49) to a summing junction (50) from which they are fed to a velocity feedback control loop (34,35,36,37) which reduces any changes in the velocity (and hence deflection) of the probe due to the accelerations.

Abstract: A coordinate positioning machine has an operating module such as a tool or probe (10) mounted for translational motion relative to a table (16) with three degrees of freedom by means of three articulated linkages (18). Each of the linkages is made up of a torsion box (22) which is pivotally mounted to a vertical pillar (20) with one degree of freedom, and a pair of struts (26), each of which is pivotally mounted with two degrees of freedom to the torsion box at one end, and to the operating module at the other. The linkages cooperate to prevent all rotational motion of the operating module, while allowing translation. Motion of the operating module is actuated manually, and the mass thereof is counterbalanced by an articulated counterbalance arm 90 which guides a cable 96 that is in turn connected to a fusee. Displacement of the operating module is measured using scale and readhead encoders (40,50).

Abstract: Vibrations of the stylus (4) of a measuring probe (1) mounted on a machine, and which are transmitted to the probe stylus via the machine quill and probe body, are reduced or eliminated by a vibration damping means positioned within a cavity of the stylus. FIG. 2 illustrates a first embodiment in which the vibration damping means is a unconstrained rubber cylinder (16), in a hollow cartridge (12) connected to the stylus at its tip. Alternatively a dynamic vibration absorber can be used.

Abstract: A retaining device comprises a holder for receiving an object and a clamp 4. The holder comprises a cylindrical sleeve 1 with three longitudinal cut-out slits 3 spaced 120° apart and a base 2 secured at one end. The inner surface of the clamp 4 has three lobes 11,12,13 also spaced 120° apart. The portions midway adjacent lobes contact the portions of the sleeve midway adjacent slits 3, resulting in a symmetrical force being applied to the circumference of the sleeve 1 when the clamp 4 is tightened. The clamp 4 is free from the base 2 of the holder and is not rigidly attached to the sleeve 1 and thus does not apply unequal forces to the holder when the clamp is tightened. Alternatively the sleeve 1 may have a thin continuous wall which deforms when forces are applied to it by the clamp 4. The object inserted into the sleeve may have a spherically shaped portion to allow is to be angularly adjusted in the sleeve before the clamp is tightened.

Abstract: An indexing mechanism comprises a disc 2 rotatable about a central axis, suitable for holding objects such as lenses. Detents 8 are provided on the disc which interact with a pawl 14 on a fixed surface adjacent the disc 2. When the disc rotates in a first direction the pawl 14 is deflected by each passing detent 8, returning to its rest position when the detent 8 is passed. When the disc is rotated in an opposite direction, the pawl 14 abuts a detent 8 to define an index position. The disc is driven or biased in this direction to retain this position. A stop 10 may be provided on the disc 2 adjacent each detent 8 which defines the position of the pawl 14 relative to the disc 2. The disc 2 may be driven by a motor 12 and drive means. An alternative system may be used in which lever 40 interacts with a plurality of protrusions 46 on the disc to rotate the disc in a first direction or bias the disc in a second direction so that the pawl 14 abuts a detent 8.

Abstract: The output frequency of a semiconductor laser beam is stabilized using a grating or another optical device which has an interaction with the beam whose parameters are sensitive to the beam frequency. The grating (130) generates positive and negative first order diffracted beams (132, 134), whose angle of diffraction is sensitive to the beam frequency, and is detected by split photodetectors AB, CD respectively. In the event of a change in beam frequency the outputs from the photodetectors AB, CD will vary to provide an error signal for the laser frequency. This error signal is insensitive to variations in angular alignment between the beam and the diffraction grating. This is because variations in frequency and variations in angular alignment cause different changes in the outputs of the photodetectors AB, CD.

Abstract: A coordinate positioning machine comprises a fixed structure including a table and a supporting frame, rigidly connected together. A movable arm is suspended from the frame by means of three powered telescopic struts, each of which is universally pivotally connected to both the arm and the frame. As a consequence, the movable arm is able to move with three rotational degrees of freedom. Movement of the arm with each of these degrees of freedom is constrained by a passive device, connected to the arm and the fixed structure, and which eliminates all rotational movement of the arm, while simultaneously permitting translation thereof.

Abstract: A mounting for optical components, e.g. in spectroscopic apparatus, has a rotatable baseplate 10, on which a plurality of quadrant-shaped mounting plates 12 can be kinematically located. Each mounting plate 12 carries respective optical components, which can be brought into and out of an optical path by rotation of the base plate 10. One or more of the mounting plates 12 carries both a housing 14 for components such as filters 20,22 and also a beam steering mirror 24 on a bracket 16. A gap is provided between the housing 14 and the mirror 24, so that the light beam 30 in the optical path can pass unhindered through the gap when this mounting plate is in an inoperative position.

Abstract: Apparatus which can be used to calibrate, or provide measurement data on, a machine. The apparatus comprises two structures each with three spherical supports spaced in a triangular array thereon. The supports may be balls or sockets. The structures are interconnected by six members and each support has the ends of two members connected to it. The members are passive extensible measuring bars and the structures are respectively connected to fixed and movable parts of a machine so that movement of the machine parts causes relative movement between the structures and varies the lengths of the measuring bars. From measurements of the lengths of the measuring bars the actual movement of the machine part can be determined. Calibration of the spherical supports is carried out using a measuring bar which is pre-calibrated in a Zerodur jig.