Abstract

Although Ronchi test is a simple and widely used test.it has long been recognized as a qualitative rather than a quantitative one. In the previous papers^1,2, we showed the electron Ronchigrams and computer simulated interferograms to confirm the possibility to use Ronchi test to obtain the aberrations quantitatively. Optical components were tested recently. We first make some sinusoidal gratings by spatial filtering method. The gratings only have three diffracted spot in their Fourier spectrum, two weak first order spots and one strong zero order spot. Those gratings were then used in Ronchi set up to test lenses and mirrors. It seems quite easy to determine the coefficient of spherical aberration accurately from the ellipses of the three-beam interferograms. With the calculated value of spherical aberration,we could also determine other primary aberrations,such as coma and astigmatism.

© 1987 Optical Society of America