Abstract: The present disclosure relates to an equipment front end module (EFEM) teaching element. The EFEM teaching element includes a memory element configured to store data describing an initial position of an EFEM robot within an EFEM chamber. A position measurement device is configured to take measurements describing a new position of the EFEM robot within the EFEM chamber that is different than the initial position of the EFEM robot. A controller is configured to determine a set of new movement commands describing a path of the EFEM robot based upon the data describing the initial position of the EFEM robot and the measurements.

Abstract: A substrate transport empiric arm droop mapping apparatus for a substrate transport system of a processing tool, the mapping apparatus including a frame, an interface disposed on the frame forming datum features representative of a substrate transport space in the processing tool defined by the substrate transport system, a substrate transport arm, that is articulated and has a substrate holder, mounted to the frame in a predetermined relation to at least one of the datum features, and a registration system disposed with respect to the substrate transport arm and at least one datum feature so that the registration system registers, in an arm droop distance register, empiric arm droop distance, due to arm droop changes, between a first arm position and a second arm position different than the first arm position and in which the substrate holder is moved in the transport space along at least one axis of motion.

Abstract: A substrate transport empiric arm droop mapping apparatus for a substrate transport system of a processing tool, the mapping apparatus including a frame, an interface disposed on the frame forming datum features representative of a substrate transport space in the processing tool defined by the substrate transport system, a substrate transport arm, that is articulated and has a substrate holder, mounted to the frame in a predetermined relation to at least one of the datum features, and a registration system disposed with respect to the substrate transport arm and at least one datum feature so that the registration system registers, in an arm droop distance register, empiric arm droop distance, due to arm droop changes, between a first arm position and a second arm position different than the first arm position and in which the substrate holder is moved in the transport space along at least one axis of motion.

Abstract: Provided is a conveyance robot replacement apparatus used for replacing a conveyance robot installed in an atmosphere conveyance chamber of a semiconductor manufacturing apparatus in order to convey a substrate. The conveyance robot replacement apparatus includes a positioning unit configured to determine a position of the conveyance robot replacement apparatus with respect to the atmospheric conveyance chamber, a holding unit configured to suspend the conveyance robot to be supported, a guide portion configured to guide advancing and retreating into and from the atmospheric conveyance chamber of the holding unit by being engaged with the positioning unit, a position adjustment unit configured move the holding unit in each of the longitudinal direction, the horizontal direction, and the vertical direction to adjust a position of the holding unit, and a connecting component connectable to the holding unit as well as the conveyance robot.

Abstract: A high voltage power block includes a high voltage power transistor; and a switch driver configured to drive a gate of the high voltage power transistor. The high voltage power block is integrated in a programmable logic device (PLD) including a programmable fabric, a signal wrapper configured to provide signals between the high voltage power transistor and the programmable fabric, and a plurality of internal components. The plurality of internal components integrated in the PLD are programmably connected and characteristics of the high voltage power transistor are programmably adjusted using the programmable fabric and the signal wrapper.

Abstract: A distance measuring apparatus includes a reference member that is installed on a surface of a first metal member; a range finder that measures a distance to the reference member; and a mounting member to which the range finder is placed. The mounting member is installed on a surface of a second metal member coupled to the first metal member via a weld. One of the mounting member and the range finder includes first and second protruding parts. The other thereof includes first and second fitting holes into which the first and the second protruding parts are fit, respectively, such that the range finder is mounted to the mounting member, and first and second pressing members that press the first and second protruding parts from first and second directions toward inner side surfaces of the first and second fitting holes, respectively.

Abstract: The present invention relates to a method and device for detecting and analyzing deposits in liquid-bearing systems. More particularly, the device relates to being able to detect and analyze deposits in a liquid-bearing systems such as industrial plants that use and store fluids. The method relates to being able to determine a distribution of the run time of a detected ultrasonic reflection signal and analyzing the distribution to determine if deposits are deposited onto a reflecting area.

Abstract: A method and system for assisting in the manufacture of composite parts such as those used for various high-strength assemblies such as aircraft wings, vertical stabilizers, racing car shells, boat hulls, and other parts which are required to have a very high strength to weight ratio. The system uses laser technology to measure the resultant surfaces of a first manufactured composite part. A computer system analyzes and compares the as-built dimensions with the required production specifications. Supplemental composite filler plies are designed including shape and dimensions. These plies are nested together into a single composite sheet and manufactured to minimize wasted material. The plies are then cut out and applied to the first part guided by a laser projection system for locating the plies on the part. The part is then re-cured. The final assembly is then re-measured for compliance with production dimensions.

Abstract: A daily checking and calibrating method of a length measuring machine is disclosed. The method includes the following steps. Step (1) is for detecting a state of the length measuring machine at a predetermined daily check time. Step (2) is for stopping the transportation of substrates upon determining the length measuring machine is in an idle state. Step (3) is for measuring coordinates of positioning marks on a substrate-carrying platform to generate a measured data file and comparing the measured coordinates of the positioning marks with predetermined standard coordinates. Step (4) is for automatically calculating a calibration value when a difference between the measured coordinates of the positioning marks and the predetermined standard coordinates is smaller than a predetermined value and updating the calibration value to a coordinate parameter file to complete automatic calibration. Otherwise, an alarm is activated.

Abstract: A calibration standard includes a base and an outside measurement gage block disposed in a recess of the base such that edges and calibration surfaces of the outside measurement gage block are protected by the base and allow access to the calibration surfaces by a caliper. A method for calibrating calipers using the calibration standard is also provided.

Abstract: An acting force is applied to a probe on the basis of a target speed serving as a probe speed in a stable copy scanning state of a target surface to be measured and a probe speed error serving as a difference between the target speed and a probe speed.

Abstract: A photo scaling guide or system configured to scale both the area and linear dimensions of wounds or objects at the same time with one device.

Abstract: A processing system employs a processing tool to process workpieces, for example cold working holes and/or installing expandable members into holes. Sensors sense various aspects of the processing. Information regarding performance of the process and/or materials may be stored, for example a hole-by-hole or a workpiece-by-workpiece basis, allowing validation of processing. Information also allows dynamic operation of the processing tool. Analysis of response relationships (e.g., pressure or force versus position or distance) may provide insights into the process and materials, and/or facilitate the real-time feedback including control, alerts, ordering replacement for consumable components.

Abstract: A method of calibrating a surface texture measurement device includes obtaining Y-axis shape measurement data and a maximum diameter portion to obtain upper and lower maximum diameter portions of a reference sphere from Y-axis upper and lower shape data obtained by relatively moving in the Y-axis direction while a downward and an upward styluses are in contact with an upper and a lower surfaces, respectively, of the reference sphere; obtaining X-axis shape measurement data to obtain X-axis upper and lower shape data of the reference sphere by relatively moving in the X-axis direction while the downward stylus is in contact with the upper diameter portion and the upward stylus with the lower diameter portion of the reference sphere; and calculating offset amounts ?x and ?z of the upward and downward styluses from center coordinates O3 and O4 obtained from the shape data.

Abstract: A calibration artifact includes an elongated body made substantially entirely of ceramic material and having a direction of elongation. A plurality of measurement elements comprising the ceramic material are integrally formed with the elongated body, each measurement element comprising a first planar measurement surface facing in a first direction. The first planar measurement surface of each measurement element is parallel to the first planar measurement surface of each of the other measurement elements of the plurality of measurement elements. The calibration artifact may be a unitary step gauge formed with a single piece of ceramic material.

Abstract: A fluid percussion system for modeling penetrating brain injury includes a fluid percussion device that takes inputs in the form of pressurized gas and electrical signals from a computer and outputs a single hydraulic pulse, or multiple hydraulic pulses in quick succession. The fluid percussion device may include a pneumatic cylinder assembly and a hydraulic cylinder assembly that is actuated by the pneumatic cylinder assembly to produce the hydraulic pulse(s) of pressurized fluid. Each pulse may be used to rapidly inflate and deflate an attached balloon (representing a brain penetrating device). The balloon may be inserted in a test specimen, and the rapid inflation and deflation of the balloon creates a lesion that simulates a penetrating brain injury. A calibration system that employs an optical sensor may be used to determine maximum balloon diameter achieved during rapid inflation.

Abstract: A vision measuring device includes: a camera which images a workpiece and transfers image information of the workpiece; a position control unit which controls an in-focus position of the camera and outputs the in-focus position as position information representing a position in a Z-axis direction; and a vision measuring machine which performs vision measurement on the workpiece based on image information and position information. The position control unit acquires and retains position information in response to a trigger signal output from the camera or the position control unit to the other at a certain timing of an imaging period during which the camera images the workpiece. The vision measuring machine calculates position information representing a position of image information in the Z-axis direction based on image information transferred from the camera and position information output from the position control unit, and performs auto-focusing control.

Abstract: A vision measuring device includes: a camera which images a workpiece and transfers image information of the workpiece; a position control unit which controls an in-focus position of the camera and outputs the in-focus position as position information representing a position in a Z-axis direction; and a vision measuring machine which performs vision measurement on the workpiece based on image information and position information. The position control unit acquires and retains position information in response to a trigger signal output from the camera or the position control unit to the other at a certain timing of an imaging period during which the camera images the workpiece. The vision measuring machine calculates position information representing a position of image information in the Z-axis direction based on image information transferred from the camera and position information output from the position control unit, and performs auto-focusing control.

Abstract: A method of operating a coordinate positioning apparatus having a surface sensor that is rotatable about at least a first axis. The method comprises obtaining a first measurement with the surface sensor at a first angular orientation and obtaining a at least a second measurement with the surface sensor at a second angular orientation. The first and second angular orientations are different to each other such that any offset of the surface sensor from an expected position will have at least a partially opposing affect on the first and second measurements. The method then compensates and/or establishes for the offset using the first and second measurements.

Abstract: An antenna in a radar sensor is vibrated at a known frequency and velocity in a direction generally normal to the antenna surface. A response received by the antenna is used to scale or calibrate sensor responses at frequencies of interest.

Abstract: A method and apparatus for combining pressure information from pressure sensors, motion information from dead reckoning or other motion sensors, such as accelerometers, gyroscopes, and geomagnetic sensors, and temperature information from temperature sensors, to separate a change in altitude from a change in environmental pressure or temperature. A change in measured pressure without any motion or change in temperature must be a weather-related barometric pressure change. If there is an associated temperature change, but no motion, and the rate of change is too fast for a normal weather change, the measured change represents a change in sensitivity of the pressure sensor with temperature, and the sensor calibration can be adjusted. A rapid change in pressure, associated with horizontal motion, but no measurable vertical motion represents a movement into a different pressure environment. Only changes in pressure that are associated with measurable vertical motion are true changes in altitude.

Abstract: A system for controlling a numerical control machine tool with movable component parts carrying tools (5) and/or mechanical component parts to be checked includes a control unit (7) and a sensor device (9) having an associated interface unit (15). A digital channel (20), through which there are transmitted measuring signals from the interface unit to the control unit, is used, at different moments and as an alternative to the measuring process, for transmitting confirmation pulse signals (ACK) consequent to request/instruction messages that the control unit sends to the interface unit. A method for controlling the machine tool includes the sending of request/instruction messages (M) from the control unit to the interface unit, for example for checking the efficiency and the operativeness of the measuring chain, and the reception of confirmation pulse signals through the transmission channel which is a component part of the measuring chain.

Abstract: A system and method for correcting surface height measurements for optical aberration is provided. Heights determined by an autofocus tool, which may depend on surface feature angles in a focus region of interest (ROI) and on the ROI location in the field of view, are corrected based on a novel error calibration. Error calibration data includes height corrections for different feature angles in images, and for multiple locations in a field of view. Height corrections are determined by weighting and combining the angle dependent error calibration data, e.g., based on a gradient (edge) angle distribution determined in the ROIs. When Z-heights are determined for multiple ROIs in a field of view, storage of image data from particular images of a global image stack may be efficiently controlled based on determining early in processing whether a particular image is a sufficiently focused “near-peak” focused image or not.

Abstract: Systems and methods, etc., to improve operations where a barrier could interfere with the tag line of a clam shell dredging bucket suspended from a crane and/or the z-axis elevation of the bucket needs to be closely determined. The systems include an elongate rigid link connecting a suspended implement such as the bucket to a holding wire hanging from the crane. The elongate rigid link can further comprise at least one anti-rotation connection element located at an upper portion of the link to attach to the tag line for horizontal/rotational control, and/or comprise at least one z-axis calibration device configured to identify a z-axis elevation of the link and thereby the suspended element.

Abstract: A system and method for correcting surface height measurements for optical aberration is provided. Heights determined by an autofocus tool, which may depend on surface feature angles in a focus region of interest (ROI) and on the ROI location in the field of view, are corrected based on a novel error calibration. Error calibration data includes height corrections for different feature angles in images, and for multiple locations in a field of view. Height corrections are determined by weighting and combining the angle dependent error calibration data, e.g., based on a gradient (edge) angle distribution determined in the ROIs. When Z-heights are determined for multiple ROIs in a field of view, storage of image data from particular images of a global image stack may be efficiently controlled based on determining early in processing whether a particular image is a sufficiently focused “near-peak” focused image or not.

Abstract: An apparatus for detecting a pipe length in an air conditioning system includes a detector to detect a signal traveled through a pipe and a first impedance coupler that couples to one end of the pipe, where the detector detects the signal traveled through the pipe at the first impedance coupler. A processor determines a pipe length based on the detected signal and a signal generator generates the signal to be sent through the pipe. A second impedance coupler couples to another end of the pipe, where the signal generator sends the signal to the pipe through the second impedance coupler.

Abstract: A measurement apparatus calibrated to measure an absolute diameter of a part in a shop floor environment. The measurement apparatus includes a calibration that includes compensation factors for thermal expansion, shifting of measurement parts (arm, support tower, and related laser), and variances of these parts. The resulting measurements report an absolute diameter of a part to a higher degree of accuracy than previously possible. Also, the calculated compensation factor eliminate the need for an isolated, climate-controlled measurement room.

Abstract: The defect correction method includes arranging a plurality of neighbor depth pixel information values of respective neighbor depth pixels, comparing a depth pixel information value of a depth pixel with a reference value, which is one of the arranged neighbor depth pixel information values, and correcting the depth pixel information value according to a comparison result.

Abstract: Embodiments of the present invention include a calibration and measurement system designed primarily for use in the rapid evaluation and characterization of open or visible wounds in patients. The invention in a preferred embodiment comprises a set of colored concentric rings, typically constructed of paper or synthetic paper. The practitioner removes only as many rings, from the center outward, until the entire wound is visible within the open aperture at the center of the remaining rings. The area dimensions of the wound are then read out from the size of the inner remaining ring. Photography optionally records the wound appearance and size. A related system is developed for linear dimensioning of wounds. This embodiment is also designed to standardize the color scheme for accurate photography wound description. The color scheme is also applicable to a linear device to accurately describe wound size. Embodiments of the invention are also useful in forensic and accident investigations.

Abstract: Distance measuring device comprising an emitter and a receiver, said emitter being arranged to produce a magnetic field by means of a resonant circuit having a resonant frequency, said receiver being arranged to pick up at said resonant frequency the magnetic field emitted by the emitter and convert the strength of the magnetic field picked up into a first signal having an energy value, said emitter being arranged to produce said magnetic field intermittently, each emission having a predetermined energy, said receiver being connected to a detector arranged to determine, by correlation of said first signal with a second predetermined signal having a waveform representative of a signal to be picked up by the receiver, a distance measurement signal representing the distance between the emitter and the receiver. The device finds its application in detectors for sleep disorders or other forms of illness.

Abstract: Alerting a user of a material inspection device to a change in thickness of a material being inspected is disclosed. A thickness offset is determined from calibration information. The calibration information identifies a time of flight of a pulse through a reference sample similar in composition to a material to be inspected. The thickness offset indicates when a thickness of a material being inspected differs from a thickness of the reference sample. A calibration thickness alarm is set, the calibration thickness alarm corresponding to the thickness offset. A change in thickness of the material being inspected is detected. The calibration thickness alarm is engaged to alert the user of the inspection device of a detected change in thickness of the material being inspected.

Abstract: A method for the calibration of measuring equipment, and measuring equipment. The measuring equipment comprises at least one first sensor, at least one second sensor and at least one reference piece. When the measuring equipment is calibrated, a moving web is supported against the reference piece and the reference piece with the moving web supported thereto is moved to different distances from the first sensor and the second sensor. Further, a distance between the first sensor and the moving web and a distance between the second sensor and the reference piece is measured at least for two different distances, and the first sensor and the second sensor are calibrated to be uniform in relation to the movement of the reference piece.

Abstract: Determination of non-linearity of a positioning scanner of a measurement tool is disclosed. In one embodiment, a method may include providing a probe of a measurement tool coupled to a positioning scanner; scanning a surface of a first sample with the surface at a first angle relative to the probe to attain a first profile; scanning the surface of the first sample with the surface at a second angle relative to the probe that is different than the first angle to attain a second profile; repeating the scannings to attain a plurality of first profiles and a plurality of second profiles; and determining a non-linearity of the positioning scanner using the different scanning angles to cancel out measurements corresponding to imperfections due to the surface of the sample. The non-linearity may be used to calibrate the positioning scanner.

Abstract: Disclosed is a navigation-training model comprises a base, a holding device for securing a surgical practice model bone to the base in a predetermined position, and a support for fixing a patient tracker onto the base at a predetermined orientation. With the fixed relative positions of the support and the holding device, constant orientation of the patient tracker and the surgical practice model bone is achieved each time they are placed on the navigation-training model. A navigation-training apparatus having the navigation-training model is also disclosed, which includes a navigation system and a surgical tool with a tool tracker. Fluoroscopic images of the surgical practice model bone are captured once and uploaded into a computer of the navigation system. The practice of the fluoroscopic images-guided orthopedic surgery can thus be carried out with the fluoroscopic images loaded onto the navigation system without the need for further fluoroscopy.

Abstract: The present invention relates to a combination calibration/verification gauge for calibrating measuring instruments with a measurement precision. More particularly, the present invention relates to a multi-function, multi-dimension length standard and works as a working standard to compare various measuring instruments on the shop floor.

Abstract: An adjustment arrangement for a measuring head, in particular an adjustment arrangement in order to simplify the calibration of a measurement probe (3) supported by a measuring head in a coordinate measuring machine, where the adjustment arrangement includes an element for the determination of the measured position of the probe ball (7), and where an element is arranged to turn or displace, or both, the probe ball in order to determine a newly measured position of the probe ball, whereby the offset of the probe ball (7) can be determined.

Abstract: A method of calibrating stack height sensing in a media stack height monitoring system in an image forming machine includes sensing the angular position of a pick mechanism arm, generating electrical signals having levels correlated to the pick mechanism arm angular positions that correspond to different stack height levels, measuring and storing at least one value corresponding to the level of the electrical signal at least at one of two calibration points: “full load” and “stack out” conditions of the media stack, estimating either the amount or percent of media sheets remaining in the media stack corresponding to measured and stored value of the electrical signal level at the at least one calibration point, and indicating either of the amount or percent of media sheets remaining in the media stack.

Abstract: An adapter can be easily used to assist a surgical navigation system to determine the effector axis or the effector plane of a surgical instrument. The adapter has a body with a geometrical feature, the geometrical feature has a known relation with a navigation tracker device that can be attached to the adapter. When the adapter is held against a surgical instrument in a non-fixed manner, the effector axis or the effector plane of the instrument can be tracked by the surgical navigation system. The method includes a calibration method to determine the known relation between the effector axis or the effector plane and the location of the navigation tracker.

Abstract: A thermometer and extensometer for cables and conductors is described. The travel time of one or more acoustic signals along a conductor is used to determine the temperature along the conductor and the length of the conductor. The acoustic frequency is selected to minimize temporal dispersion of the propagating acoustic energy. The technique can be used to measure the temperature of the windings in a transformer or other electrical apparatus.

Abstract: A thermometer and extensometer for cables and conductors is described. The travel time of one or more acoustic signals along a conductor is used to determine the temperature along the conductor and the length of the conductor. The acoustic frequency is selected to minimize temporal dispersion of the propagating acoustic energy. The technique can be used to measure the temperature of the conductor in a buried, undersea or submerged electrical power cable.

Abstract: Apparatus of easily controlling the Z-position of the probe used in a microprobe analyzer. The apparatus has: (A) a holder, (B) a reference body having a reference surface that is at the same height as a surface of a sample, the reference body being placed on or in the holder, (C) a probe-positioning device for bringing the probe into contact with the reference surface, (D) a controller for controlling motion of the probe-positioning device in the Z-direction, (E) position-measuring apparatus for measuring the Z-coordinate of the probe at which it is in contact with the reference surface, (F) a memory for storing a positional coordinate outputted by the position-measuring apparatus, and (G) probe contact detection apparatus for detecting that the probe is in contact with the reference surface.

Abstract: The invention relates to a calibration standard, especially for the calibration of devices for the non-destructive measurement of the thickness of thin layers with a carrier plate (16) of a basic material and a standard (17) applied on the carrier plate (16), said standard having the thickness of the layer at which the device is to be calibrated, wherein that a holding device (22) arranged on the basic body (12) of the calibration standard (11) receives at least the standard (17) to the basic body (12) such that upon setting a measuring probe of the device for the non-destructive measurement of thin layers onto the standard (17), its position will be changeable by at least one degree of freedom.

Abstract: A method and apparatus for calibrating a metrology tool are disclosed. The apparatus includes a substrate having at least one calibration site formed thereon. The calibration site includes a pattern of cells that have at least one feature disposed in a surface of the substrate. The feature provided for measurement by a step height metrology tool and a phase metrology tool to calibrate the step height and phase metrology tools.

Abstract: In probing by scanning a workpiece (71) to be measured using a coordinate measuring machine a stylus tip is moved before the scanning along a scanning path (73) along an initialization path (83) or/and after the scanning path (73) along a finalization path (85). A length (Lv, Ln) of the initialization path, respectively finalization path, is chosen in dependence of parameters of a concrete measuring task, in particular in dependence of a pre-determined scanning speed, a stiffness of the stylus or a mass of the stylus.

Abstract: A liquid cartridge for supplying liquid to an external device connected therewith is provided with a casing, a partition member movably fitted in the casing, which partitions the casing into a first chamber and a second chamber, an outlet port communicating between the first chamber and the external device and a pressure unit housed in the second chamber, which presses the partition member so as to discharge the liquid out of the outlet port.

Abstract: The invention relates to a method and arrangement for measuring a timber piece (4) in a wood handling machine (1). Such a wood handling machine comprises booms (2) arranged in a base machine and a wood handling device (3) operating therein. In such a wood handling machine (1), a wood handling device (3) grips the timber piece (4) to be handled, after which one end of the timber piece is guided into a measuring carriage (5) in the wood handling machine by the wood handling device. The timber piece arranged in the measuring carriage is subjected to one or more observation measures by observation means provided in the measuring carriage.

Abstract: A coordinate measuring machine to determine the coordinates of a number of points on the surface of a measured object, includes a support beam, supporting a measuring head over the surface of a support table that supports the test object. The measuring machine is constructed from separately manufactured units, which include at least a support beam, a measurement trolley and a measurement head. The support beam supports the measurement trolley, which is displaceable along the support beam. The measurement trolley in turn supports the measurement head. The beam, head and trolley are individually calibrated, and the trolley includes both mechanical and electrical attachment points for the head and the beam, where the mechanical attachment points are designed such that no geometric deformation can take place when these units are joined together such that the units, which have been individually manufactured, can be simply joined to the coordinate measuring machine.

Abstract: Measurement devices and methods for measuring balloon catheters are provided. Embodiments enable measuring the outer dimensions and burst pressure of a balloon catheter. The measurement apparatus can measure a balloon catheter in ambient air or a balloon catheter submerged in a heated water bath. In ambient air, an axial drive mechanism translates the balloon catheter in an axial direction and a rotary drive mechanism rotates the balloon catheter while a measurement device is used to measure balloon catheter dimensions. In a water tank, an axial drive mechanism translates the balloon catheter in an axial direction while a measurement device is used to measure the burst pressure of the balloon catheter. The devices and methods can utilize a laser micrometer in order to provide such measurements. A control unit provides a user interface and is capable of displaying real time data during the measurement process.

Abstract: A thermometer and extensometer for cables and conductors is described. The travel time of one or more acoustic signals along a conductor is used to determine the temperature along the conductor and the length of the conductor. The acoustic frequency is selected to minimize temporal dispersion of the propagating acoustic energy. The technique can be used to measure the temperature and sag of an overhead power line, the temperature of the windings in a transformer, or the temperature of the central conductor in a coaxial power cable.

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.