Final answer:
The index point on an ultrasonic angle beam probe is checked on a calibration block to ensure proper calibration and accuracy of the beam angle.
Step-by-step explanation:
An ultrasonic angle beam probe is used in ultrasonic imaging applications to produce images of internal structures. The index point on the ultrasonic angle beam probe is checked on a calibration block. This is to ensure that the probe is properly calibrated, and the angle of the beam is accurate.