In order to measure aspherical surfaces more accurately, the influence of test device on measurement error was analyzed. Instead of ronchi grating, sinusoidal grating was used to test aspherical mirrors based on the Ronchi method.By synchronous phase detection technology and geometrical theory, shape deviation gradients of all tested points could be obtained. Then the surface of the tested mirror was reconstructed after restoring shape deviations using area wave-front reconstruction method.The influence of combination fringes, asphericity and grating contrast on reconstructed tested surface were presented.The numerical results showed that both the combination fringes and grating contrast affect the testing accuracy of aspherical surface, and the error of reconstruction increases with asphericity.The results may provide an affective and reliable basis for Ronchi test device.
