Abstract: In a touch sensor for detecting the deflection of a feeler pin or the like, which is mounted for movement against a pressure element in a housing (1, 27), the pressure element is to consist of two magnets (23, 24) of opposite polarity, one of them being associated with the feeler pin or the like.

Abstract: A touch probe has a sensing module 10 and a stylus module 12 magnetically retained and kinematically located thereon. A stylus holder 102 is biased into a kinematic rest location within the stylus module 12. The sensing module 12 has a fixed structure provided by connector 14, cylindrical housing 16, and circuit supporting structure 18. An intermediate load member 30 is connected to structure 18 at one end by means of a relatively resilient diaphragm 40 and at the other by three supporting struts 50, extending at an angle of 45.degree. to the axis A. The load member 30 carries a circular retaining plate 22 upon which the stylus module 12 is located. During a measurement operation, a force applied to stylus tip 112 will cause bending of struts 50, and deformation of diaphragm 40 prior to movement of the stylus holder 102 out of its kinematic rest position. Strain gauges provided on the struts 50 detect this bending and generate an output signal accordingly.

Abstract: An indexing mechanism includes a first body and a second body. The first and second bodies are rotatable relative to each other about a plurality of index positions which are provided at discretely spaced angular orientations about the axis. The bodies are relatively moveable in an axle direction to facilitate disengagement from a given index position.

Abstract: An opto-electronic scale reading apparatus includes a reflective scale (410) relative to which a readhead is movable. The readhead includes a light source in the form of the emission end of an optical fiber (300), which directs light via collimating lens (420), beam splitter (310), and deflecting optics (312,314) onto the scale. The light reflected from the scale passes through an index grating (416) to generate a series of spatial fringes in the plane of an analyzer (418). The analyzer comprises a series of elongate light transmitting color filters, extending substantially parallel to the fringes and arranged in a repeating pattern (e.g. red, blue, green, red, blue . . . ); like-colored elements are separated by a distance corresponding to an integer multiple of the fringe pitch. The array (418) encodes the fringes into a plurality of phase-shifted signals, which pass through the beam splitter (310), lens (420) and back along fiber (300).

Abstract: A mounting device for a telescopic ball-bar has a hexagonal shank retained in jaws of a chuck on a spindle of a lathe. A supporting bracket extending from the shank carries a magnetic socket in one of a plurality of locations, and receivably mounts one end of the ball-bar for universal pivotal motion. The configuration of the bracket, the spacing between the socket and the shank, and the orientation of the socket, are such that the other end of the ball-bar, which is universally pivotally mounted to the tool post of the lathe, may execute a circular trajectory of greater than 180.degree., which trajectory intersects the axis of rotation of the lathe.

Abstract: To provide a better seal for example in an indexing arm for a machine tool to prevent swarf getting to the rubber seal, an outer spring seal is provided. The seal takes the form a closely wound coil spring formed into a ring and positioned in a slightly expanded state in a vee-grove at the entrance to the space being sealed. The spring is compliant enough to allow for slight axial and transverse relative movements of the two parts of the arm and is hard enough not to be damaged by swarf or the limited relative rotation between the parts during indexing.

Abstract: A sample placed under a microscope is illuminated by light from a laser beam. Raman scattered light is passed back via a dichroic filter to various optical components which analyse the Raman spectrum, and thence to a CCD detector. The optical components for analysing the Raman spectrum include tunable dielectric filters in a filter wheel; a Fabry-Perot etalon; and a diffraction grating. These various components may be swapped into the optical path as desired, for example using movable mirrors, enabling the apparatus to be used very flexibly for a variety of different analysis procedures. Various novel analysis methods are also described.

Abstract: Apparatus which can be used to calibrate a machine or as a machine itself includes two structures, each with three 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. When used as a calibration device, 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 calibrated. When used as a machine, the members are powered struts by means of which one of the structures, which carries a tool or a probe can be manipulated relative to the other, to position the tool or probe relative to a workpiece.

Abstract: A probe head for a coordinate measuring machine is provided with a heat control management system which regulates the amount of heat generated within the probe head in order to provide thermal stability thereof. The heat control system includes a processor which determines the amount of current passed to one or more motors within the probe head over a predetermined time interval. The processor then determines whether auxiliary heat sources should be activated in order to provide thermal stability. In one embodiment the auxiliary heat sources are provided by passing a high frequency current through the motors of the probe head.

Abstract: An interface circuit for processing signals from a touch trigger probe is adapted to prevent the generation of false trigger signals during an inspection cycle. The probe incorporates a plurality of strain gauges, the voltage across which rises above a predetermined threshold when a stylus supported by the probe contacts a surface. When the probe is moved away from the surface and the stylus loses contact, the outputs across the gauges drop below the trigger threshold. The interface prevents false triggers When, while the stylus is in contact with a surface, a machine vibration occurs which causes an oscillation in the voltage across the gauges; the voltage dropping below the threshold level (causing the interface to reset), and then immediately passing back up through the threshold, causing the interface to emit a trigger signal.

Abstract: A touch trigger probe for a coordinate measuring machine or machine tool has a stylus, which is biased into a rest position. The stylus has two independent supports, provided within a housing. A first support comprises a skirt of a stylus holder which is axially constrained on a surface of the housing. The second support comprises a kinematic arrangement of cylinders and balls, together with a planar spring, which together provide lateral constraint. The first support is biased by a much lighter force than the second support, so that its friction is very low. This reduces the lobing and hystersis of the stylus movement, and thereby increases the accuracy of the probe. The stylus movement first takes up a clearance between the first support and an abutment surface of the housing and then disengages the kinematic arrangement of the second support upon further stylus movement.

Abstract: A trigger probe 10 has electrical contacts which open when the probe contacts a workpiece. This is detected by a comparator 17 to produce a trigger signal. If spurious signals are generated at the probe contacts as a result of vibration, these are filtered out by a capacitor C1, which charges up when the contacts open and introduces a time delay. When the probe contacts re-close after a normal trigger operation, the capacitor C1 is discharged through a discharge circuit, e.g. transistor TR1, so that the energy stored on the capacitor does not damage the probe contacts.

Abstract: A method is disclosed whereby a probe head which articulates a probe on the moveable arm of a coordinate measuring machine is calibrated to reduce the effect of errors, such as misalignment of the rotary axes of the head, and droop of the head and the probe. The method involves measurement of the probe position at a number of orientations of the head, the angle of orientation being determined by encoders within the head. Pairs of adjacent orientations at which the probe position is measured define segments, over which it is assumed that all errors change linearly. From the measured probe positions, a value of actual angular displacement between measured probe positions is calculated.

Abstract: A diffraction grating receives a laser beam from a semiconductor laser diode. Light is diffracted in a first order of diffraction of the grating, through an aperture which selects a desired wavelength, free from side modes of the laser diode. A minor proportion of the light is reflected back by a glass window, and is fed back into the laser diode to stabilise it, preventing mode hopping. The majority of the light of the desired wavelength passes through the window to an output. Because the output light is both free from side modes and not subject to mode hopping, it is suitable for use as the exciting light in spectroscopy, including Raman spectroscopy.

Abstract: An arm 12 for holding a tool-setting probe 14 in a machine tool is rotatable between an operative position and an inoperative position. The operative position is defined by elements 48,52 which form a stop against further rotary motion beyond the operative position. These elements 48,52 are arranged as a kinematic support, so that the operative position is defined in a precisely repeatable manner. Springs 40 urge the elements 48,52 together. When the arm is in the operative position, these springs are stretched by a repeatable amount, so that they provide a repeatable force, in order to increase the precision of the operative position.

Abstract: In a Raman spectrometer having a charge-coupled device (CCD) detector (24), an incoming beam (36) containing a spectrum of Raman scattered light is dispersed by a diffraction grating (44). Different parts of the spectrum are split into separate optical paths (48A-C) by edge filters (38A, 38B) and a mirror (46). These components are tilted at different vertical angles, so that after the beams (48A-C) have been dispersed by the diffraction grating (44), they form partial spectra (50A-C), one above the other on the CCD (24). This enables several consecutive parts of a widely dispersed spectrum to be viewed simultaneously on the CCD (24) at high resolution.

Abstract: A laser interferometer, used for measuring displacement over long distances (e.g. 100 meters) includes an integral laser/detector unit 10, which emits a beam 12 of laser light. The fraction of the beam 12B which passes undiverted through a beam splitter 14 is laterally displaced by a periscope 18, which is positioned close to the laser 10. After passage through the periscope 18, the undiverted beam is incident upon a large retroreflector 20, whose size is such that the beam reflected by retroreflector 20 is laterally displaced by an amount greater than the lateral displacement due to passage of the beam through the periscope 18. Opaque housing 26 of the periscope 18 is used to screen reflected light from entrance into the laser cavity.

Abstract: A measuring probe has a stylus carrier supported on a fixed member in a rest position when no force acts on the stylus, the stylus carrier being deflected from its rest position to produce a signal when an external force is applied to the stylus. The support for the stylus carrier comprises two concentric rings of ball bearings of different pitch circle diameters and arranged that each ball on one of the members contacts two adjacent balls on the other member. An additional annular surface is provided on one of the members and is contacted by each of the balls on the other member. The arrangement provides that the force required to deflect the stylus is substantially equal in all directions of the force, and that the movable member is properly guided during its deflection to the point where a signal is produced.

Abstract: In a Raman microscope, Raman scattered light from an illuminated area on a sample 10 is collected by an objective 12 and imaged by a lens 18 onto a detector in an image plane 20. A filter 16 selects only light of a desired Raman wavenumber shift. Since the tuning of this filter is sensitive to the angle of incidence, it is placed after the lens 18 instead of before it, and the distance from the objective 12 to the lens 18 is made substantially equal to the focal length of the lens 18. This ensures that chief rays 14A',14B' from different points on the sample 10 pass through the filter 16 at the same angle of incidence. The wavenumber selected by the filter is therefore the same for light from all points on the sample, which it would not be if the filter were placed before the lens 18.

Abstract: A hexapod machine comprises a fixed structure (10,11) and a movable structure (14,15). Six extensible legs (18) are connected between the fixed and movable structures, and their lengths determine the relative position and orientation of the structures. The lengths of the legs are measured by respective laser interferometers (60,62). To increase the accuracy of the measurement, a retroreflector (62) of the interferometer is directly mounted to and fast with one of the structures (14,15).