Enhancement of accuracy in OTF measurement.

ABSTRACT

A knife-edge scanning method was developed to enhance the accuracy in OTF measurement. A slit image formed by the lens under test was scanned by a knife-edge which was moved by a stepping motor. It was possible to increase the signal-to-noise ratio with averaging 4-32 data at each point through a scan. The standard deviation was decreased to under 0.25% in the MTF unit.