Abstract: Disclosed is an interferometry system for measuring one or more properties of a test object, wherein the interferometry system is configured for use with at least one exchangeable optical element, and the interferometry system includes: an interferometer configured to combine a test wavefront derived from the test object with a reference wavefront to form an optical interference pattern on a detector when the test object and the exchangeable optical element are optically coupled with the interferometer; and an electronic controller coupled to interferometer and configured to analyze the optical interference pattern to determine metrology information about the test object; wherein the electronic controller is further configured to receive information from the exchangeable optical element, obtain calibration data about the exchangeable optical element based on the received information, and use the calibration data to reduce measurement uncertainty when determining the metrology information about the test object