The knife edge testing of optics is well known to be a sensitive but subjective test of an optical system. This test has been successfully used to figure telescope mirrors to a high degree of perfection. The problem with this test was that it was difficult if not impossible to get useful numbers as to the magnitude of error in the optic under test. With the advent of solid-state memory, microcomputers, and video sensors, we are now able to collect the information required to quantify the data available from the knife edge trace. The key to the new knife edge bench is the use of solid-state memory to capture and store pupil data so that it can be processed by the microcomputer. The system being described uses Zernike polynomials to bridge the gap between the subjective test and the objective measure. The Zernike polynomials are used to develop coefficients from the knife position. These Zernike coefficients are then converted to wavefront by using straightforward matrix operations.