1. Calibration of incidence point (probe front edge): Use an IIW test block (also known as a Dutch test block) or CSK-IA test block to measure the zero point of the inclinometer probe, adjust the instrument's sound speed to 3230m/s, display a range of 150mm, and then start the test. The user places the probe on the test block and moves it so that the reflector echo of the R100mm circular arc surface reaches a high level. Use a ruler to measure the distance between the probe front end face and the R100mm arc center of the test block. This value is the front edge value of the probe, and the position on the probe corresponding to the R100mm arc center is the probe incidence point.  

The calibration of angle probes usually requires the following steps:

1. Calibrate the incident point (probe front);

2. Calibrate probe angle (K value);

3. Calibration material sound speed;

Calibrate the probe zero point.

2. Calibrate probe angle (K value): Probes calibrated with angle values can be calibrated using IIW test blocks, while probes calibrated with K values can be calibrated using CSK-IA test blocks. These two types of test blocks have rulers with angles or K values. Choose the appropriate ruler according to the nominal value of the probe (the upper side of the IIW test block can calibrate probes at 60-76 degrees, the lower side can calibrate probes at 74-80 degrees, the upper side of the CSK-IA test block can calibrate probes at K2.0, K2.5, K3.0, and the lower side can calibrate probes at K1.0, K1.5). Please select the appropriate calibration block and calibration method based on the calibration values on the test block. Place the probe as shown in the figure and move it left and right to make the reflector echo reach a high level. At this point, the scale corresponding to the incident point is the angle or K value of the probe.

3. Calibrate the sound velocity of the material as described in section 1 to find the high reflection wave of R100mm, adjust the display range so that the secondary echo of the curved surface can be displayed on the screen, select the double gate mode, adjust gate A to intersect with the primary echo, adjust gate B to intersect with the secondary echo, adjust the sound velocity value so that the measured value (S) of the sound path in the state line is 100, and the obtained sound velocity value is the actual sound velocity value of the material.

4. Calibrate the probe zero point to maintain the measurement state above, change the gate mode to positive or negative, adjust the probe zero point so that the sound path measurement value (S) in the state line is 100 again, and the obtained probe zero point value is the zero point value of the probe.

There are many calibration methods for angle probes, which are not strictly limited to using standard test blocks for calibration. They can also be calibrated using small holes of known depth. In theory, the smaller the reference reflector, the higher the calibration accuracy, but the difficulty of calibration also increases accordingly. When calibrating with a small hole, the angle can be calibrated by measuring the depth and horizontal position of the hole, calculating the slope, and using the measured depth or horizontal position value to calibrate the sound velocity and probe zero point.