Edge Gradient Analysis Otf Accuracy Study

The optical transfer function (OTF), obtained with the Perkin-Elmer edge gradient analysis (EGA) measurement technique, is a complex function consisting of the modulation transfer function (MTF) and the phase transfer function (91F). Previous experiments demonstrated the EGA technique to be accurate for measuring the modulation transfer function. An experiment was conducted to test the Perkin-Elmer automated EGA technique as to its accuracy in measuring the phase transfer function. Experimental equipment was designed to pro-duce photographic edges with a theoretically known phase component. The experimental apparatus provided sinusoidal image motion to an edge test target while it was photographed with a high quality optical system. The resulting photographic edges were degraded by a known amount of sinusoidal image motion during exposure. These edges were measured using the EGA procedure. The experimental values for all OTF effects other than that due to sinusoidal image motion were then removed. The resultant OTF's were compared to the theoretically derived values for the appropriate sinusoidal image motion. The results demonstrate that the EGA technique is an accurate method of measuring both the modulation transfer function and the2hasetran'sfer function over the spatial frequency region tested.