Measurement of focal length using phase shifted moiré deflectometry

In present communication, a simple technique for determining the focal length using moiré deflectometry has been proposed. Necessary mathematical premise expressing the focal length of lens in terms of defocusing distance and the slope of wavefront phase has been deduced. Using a four-step phase shifting technique the testing procedure for determining the focal length has been demonstrated. Uncertainty in measurement has been estimated. Good co-relation between the measured value and the standard value has been obtained.

► Direct phase measurement using phase shifting interferometry has been used for measurement of focal length. ► Very simple, inexpensive and robust design of experimental setup. ► Improved measurement characteristics have been achieved.