Step 2: Calibrate the Laser Probe

The calibration process that this step describes varies based on the type of measure laser probe options and the type of installed interface. For detailed information on calibration options, refer to the "Measure Laser Probe Options" topic in the PC-DMIS Laser documentation.

The following steps outline the procedure to use when you first calibrate your laser probe:

1. Once the tip is defined in step 1, click Measure from the Probe Utilities dialog box. This opens the Measure Laser Probe Options dialog box.

2. Click Measure to begin the calibration procedure. If you are NOT using a Perceptron V5 sensor, skip to step 5. If you are using a Perceptron V5 sensor, you are first prompted to scan the entire range of the laser's Z depth on a flat target.

3. Measure the Z-depth of your V5 sensor (flat target calibration) by doing the following:

1. Place a white piece of paper on a flat surface where you intend to perform the flat target calibration.

2. Hold the V5 sensor close to the flat surface so the scan line is beyond the laser's projected grid box.

3. Press and hold the sensor's trigger while you move the probe away to the full extent of the laser's range so that the laser line crosses the grid box to the other side.

4. Release the trigger. This completes the flat target calibration.

4. Follow any on-screen instructions and visual indicators from the Laser tab to complete the sensor calibration on the calibration sphere.

1. You are prompted to move the probe to 15 different locations on the calibration sphere (5 different positions around the sphere with 3 different fields at each position). The laser probe will continually be probing, but it only accepts a stripe of data when certain criteria are met. The system needs 5 stripes of data at each of the 15 different locations to complete the calibration.
   
   When you calibrate in the three fields ("far", "left", and "right") for the 5 different positions, be sure to take a hit (laser stripe) at both of the tropics. The tropics are indicated as "Band 1" and "Band 2" in the above image located in the drop-down link). Also, when you probe at 0, 120, and 240 degrees around the equator, favor the lower part of the sphere by taking 2 stripes on the lower location and only 1 on the upper location. This is because additional data will be taken during sets 4 and 5 which occur on the top of the sphere.

   Graphical Depiction of the Different Probing Locations

   • 5 Positions around the sphere:

   Position 1: The laser stripe should be horizontal along the side of the sphere as in the image below.

   

   Position 2: Rotate the sensor 120 degrees around the sphere from Position 1.

   Position 3: Rotate the sensor 120 degrees around the sphere from Position 2.

   Position 4: Point the sensor straight down on the top of the sphere.

   Position 5: Point the sensor straight down on the top of the sphere with the laser stripe located 90 degrees from Position 4.

   • 3 Sensor Fields (Far, Right, and Left) within the laser's range:

   Field 1: Far	Field 2: Right	Field 3: Left

   • 2 Bands on the sphere's surface. Hold the probe within either of these bands for five stripes.

   

   Band 1: 20 Degrees above the equator (mid-line) of the sphere.

   Band 2: 20 Degrees below the equator (mid-line) of the sphere.

    

   Criteria for an Acceptable Stripe:

   • The probe must not be against the hardstop of the arm.

   • The stripe must have more than 100 points.

   • In the Laser View, the laser's red arc must be inside the green rectangular area that bounds the yellow arc.

   • The solved circle that is created by the laser's arc must have at least 100 degrees of arc angle. This is the difference between the starting vector and the ending vector of the arc.

   • The laser must probe a diameter of .875 multiplied by the theoretical diameter of the calibration sphere. This means it should probe between 81.9% and 96.6% of the theoretical diameter.

   • The probe must remain motionless. It should not move more than 1.5 mm over the last 5 probings.

2. For each hit (or laser stripe) of the calibration, use the Laser tab to align the red arc of the laser with the yellow arc (representing the sphere's theoretical arc) so the form and size match as close as possible.

3. Move the laser's red arc so that it remains within the green rectangular box surrounding the yellow arc. As you position the laser's arc on top of the yellow arc, an audible beeping sound increases in frequency and pitch. This helps you know when you are approaching the desired location.

4. Hold the laser probe motionless at the appropriate location until the various criteria are met. PC-DMIS automatically accepts the stripe and prompts you to probe at a new location.

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