Contact Imaging Sensor Automated Resolution Testing Using Stationary Test Objects

A method is described to test the resolution of a contact imaging sensor within a depth of field (DOF) as a function of the distance from the sensor surface. Conventional characterization methods scan resolution test patterns at multiple intervals within the DOF, and calculate the modulation transfer function (MTF). This approach is time-consuming and requires mechanical moving parts. This paper describes an alternative measurement technique that measures: (1) focal distance from the sensor surface and (2) MTF within the DOF. The method utilizes several resolution test targets and a stationary mechanical apparatus. Data from four stationary line-scan images are analyzed, and the focal distance and MTF are calculated. This method reduces measurement time drastically, and eliminates the need for mechanical scanning.