Collapsible three=dimensional calibration test body for measuring or positioning instrument

摘要

The test body is tetrahedral. The test body has four balls at the corners, which serve as contact form elements, and six rods which serve as connecting elements between the balls. Each ball touches exactly three connecting elements at their end sections, and the ball centres lie approximately on the extensions of the rod axes.The relative positions of the rods with respect to each other are fixed through the balls, or through holders mounted at the balls holder in their position.