Calibration

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CalibrationClosed A series of measurements that check the accuracy of the [[[Undefined variable _FAROc_Migrate-from-FM.Hardware Name]]] against known standards. is the procedure where the performance of a measurement device is verified. There are simple checks that you can perform to ensure the device is working optimally. In this section we will explain two probing performance checks and two scanning performance checks.

Both the ball probe and the Laser Line Probe must be properly compensated before starting any calibration testing. For more information, see FARO Prizm Laser Line Compensation.

Probing Performance Check

There are two methods for performing the Probing Performance Check:

Method 1 - Single Point Test

Perform the single point repeatability test to check the ball probe and repeatability using a hole or a cone. You must use a firmly secured object with a hole at least 1 mm smaller than the ball probe. If a cone hole is used, extreme care must be taken to ensure that the probe is seated at each “measurement.”

For more information, see Single Point Articulation Test (SPAT).

Method 2 - Sphere Test

  1. Attach a sphere to your work surface within approximately ⅔ of the ScanArm's reach.

  2. Select the ball probe.

  3. Measure the sphere with a minimum of nine (9) readings - evenly distributed over the surface of the sphere.

  4. Measure the sphere in the same method at least two more times.

  5. Use the software command to get the distance from the center of a sphere to the center of another. The distance from any sphere to another should not exceed the system precision of the ScanArm:

    • 2.5 M Length - 0.075 mm (0.003 in)

    • 3.5 M Length - 0.110 mm (0.004 in)

    • 4.0 M Length - 0.130 mm (0.005 in)

If any test fails, print the results and repeat the calibration two more times. Print all of the results and contact FARO ’s Customer Service by Phone, Fax or Technical Support.

Scanning Performance Check

There are two methods for performing the Scanning Performance Check:

Method 1 - Plane Test

  1. Attach the calibration plate to your work surface within approximately ⅔ of the ScanArm's reach.

  2. Select the Laser Line Probe (LLP).

  3. Scan a plane in a single sweep, while following a straight path, with an even distribution of points over the surface of the plate.

  4. Use the software command to create a plane from the cloud of scan points.

  5. Scan the plate again in the same method but rotate the laser line 90°.

  6. Use the software command to create a plane from the second cloud of scan points.

  7. Use the software command to get the distance between the two planes. The distance should not exceed the system precision of the ScanArm:

    • 2.5 M Length - 0.075 mm (0.003 in)

    • 3.5 M Length - 0.110 mm (0.004 in)

    • 4.0 M Length - 0.130 mm (0.005 in)

Method 2 - Sphere Test

Use an optical scanning sphere larger than 25 mm (1 in). These spheres are typically white or gray with a matte finish.

  1. Attach a sphere to your work surface within approximately ⅔ of the ScanArm's reach.

  2. Select the Laser Line Probe (LLP).

  3. Scan the sphere with an even distribution of points over the surface of the sphere.

  4. Use the software command to create a sphere from the cloud of scan points.

  5. Scan the sphere in the same method at least two more times.

  6. Use the software command to get the distance from the center of a sphere to the center of another. The distance from any sphere to another should not exceed the system precision of the ScanArm:

    • 2.5 M Length - 0.075 mm (0.003 in)

    • 3.5 M Length - 0.110 mm (0.004 in)

    • 4.0 M Length - 0.130 mm (0.005 in)

If any test fails, print the results and repeat the calibration two more times. Print all of the results and contact FARO ’s Customer Service by Phone, Fax or Technical Support.