Effects of Difference in Spatial Frequency Response of Sensors When Measuring Straightness Using Multiple Sensors.

Abstract

This paper presents transfer functions that include the characteristics of sensors, in the case of measurig straightness using sensors, e.g., 2-point method. When sensors exhibit symmetrical spatial frequency response regarding the center of their aperture, difference in their spatial frequency response causes phase shift in the results of measurement. When sensors show asymmetrical response with respect to the aperture, to avoid deviation of gain in the low-frequency domain, it is important to grasp the center of gravity of sensor's intensity in the spatial domain. In the case of the 3-point method, difference in the sensors causes deviation of the transfer function of the system. However, in the case of differential laser autocollimation, the transfer function is stable.