K-21KMitutoyo operates a policy of continuous improvement that aims to provide the customer with the benet of the latest technological advances.Therefore the company reserves the right to change any or all aspects of any product specication without notice.■Measurement along Multiple Portions of an ImageLarge features that cannot be contained on one screen have to be measured by precisely controlling the position of the sensor and stage so as to locate each reference point within individual images. By this means the system can measure even a large circle, as shown below, by detecting the edge while moving the stage across various parts of the periphery. ■Composite Coordinates of a PointMeasuring machine stage positionM = (Mx, My, Mz)Detected edge position (from the center of vision)V = (Vx, Vy)Actual coordinates are given by X = (Mx + Vx), Y = (My + Vy), and Z = Mz, respectively.Since measurement is performed while individual measured positions are stored, the system can measure dimensions that cannot be included in one screen, without problems.■Principle of Auto FocusingThe system can perform XY-plane measurement, but cannot perform height measurement using only the camera image. The system is commonly provided with the Auto Focus (AF) mechanism for height measurement. The following explains the AF mechanism that uses a common image, although some systems may use an AF laser.The AF system analyzes an image while moving the camera up and down in the Z axis. In the analysis of image contrast, an image in sharp focus will show a peak contrast and one out of focus will show a low contrast. Therefore, the height at which the image contrast peaks is the just-in-focus height.■Variation in Contrast Depending on the Focus ConditionEdge contrast is low due to out-of-focus edges.Edge contrast is high due to sharp, in-focus edges.MMzMyMxVxVyVMachine coordinate systemVision coordinate systemCameraZ coordinateIn-focus heightContrastHighHighLowLowContrast in the scanning directionContrast in the scanning directionVision Measuring MachinesQuick Guide to Precision Measuring InstrumentsISO10360-7 (Geometrical product specications (GPS) -- Acceptance and reverication tests for coordinate measuring machines (CMM) -- Part 7: CMMs equipped with imaging probing systems) was published on June 1, 2011.Some inspecting items are listed in ISO10360-7. The following summarizes the test method for determining length measurement error (E) and probing error (PF2D). Length measurement error, EFive test lengths in seven different directions within the measuring volume, each length measured three times, for a total of 105 measurements. Four directions are the space diagonals; remaining three positions are user specied; default locations are parallel to VMM axes.When CTE (coefcient of thermal expansion) of the test-length artifact is < 2×10-6/K, additional measurement of artifact with normal CTE (8 to 13×10-6/K) is performed.Probing error, PF2DMeasure 25 points distributed evenly around the test circle (14.4º pitch).Each of the 25 points shall be measured by using the specied 25 areas of the eld of view.Calculate probing error as the range of the 25 radial distances (Rmax - Rmin) from the center of the least-square circle.■Overview of ISO 10360-74 positions (space diagonals) 3 positions(user specied) Normal CTE additional inspectionField of view


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