!%Precitech Inc.%! of Keene, N.H., and !%14560%%Taylor Hobson%! of Leicester, UK, have developed a technique to measure, analyze and correct for diffractive form errors in three dimensions. The process uses Taylor Hobson’s PGI 3-D with advanced aspherics analysis software, along with its CCI optical profiler, and Precitech’s NanoForm 250Ultra with a rotary B axis and a fast tool servo. Precitech provides ultraprecision single-point and multiaxis diamond-turning machines for rotationally symmetric and free-form applications in nonferrous, ferrous and high-performance metals.