The CaliBall™ is used to calibrate interferometer transmission spheres. The CaliBall™ does this using the Random Ball Test (RBT) described in papers in the Technical Library under CaliBall papers. Please register (below left) to view these informative papers.               

To perform a calibration the CaliBall™ is positioned in x, y    and z so that its center is at the focus of the transmission sphere so light is reflected back into the interferometer by the convex ball surface. An interferogram is taken and stored. The CaliBall™ is lifted out of its kinematic mount, rotated to an arbitrary new position and replaced in the mount. Another interferogram is taken and averaged with the first. The process is repeated several times. The average is an estimate of the residual error in the transmission sphere because the errors in the CaliBall™ average to zero in the limit of a large number of tests.

The CaliBall™ is supplied with a three ball kinematic mount potted in a substantial steel base that is cut away on one side so f/0.7 transmission spheres can be calibrated. The CaliBall™ is shipped with a Certificate showing roundness and finish, complete instructions for use and a clean room compatible storage case.

CaliBall is available directly from OPG and we accept all major credit cards.

To order, please (click here), or call or send message using the Contact Us page.

OPG announces a new version of the CaliBall™ that requires no additional hardware.

(click here) to view CaliBall2™