Automatic measurement of the modulation transfer function of an optical system

摘要

A system and method are described for automatically determining the modulation transfer function (MTF) of an optical system. In accordance with exemplary embodiments of the present invention, optical information is collected from the optical system by imaging a bar target having at least one associated frequency to provide a bar target image for a first focus setting of the optical system. A first MTF of the optical system is determined for the at least one associated frequency at the first focus setting from the bar target image. The steps of collecting and determining are repeated by automatically selecting at least a second focus setting of the optical system to determine at least a second MTF for the at least one associated frequency. An MTF for the at least one associated frequency of the optical system is determined by interpolating the first and at least second MTFs. According to exemplary embodiments, a bar target with alignment holes is used for automatically determining the orientation of the bar target. In an alternate exemplary embodiment, an open-hole DC target is used to calculate the DC response of the optical system.