Quantitative three-beam Ronchi test.
Sinusoidal gratings made by either the spatial filtering method or holography are used in a Ronchi setup to test lenses and mirrors. The interference between the strong zero-order and two weak first-order wavefronts gives a three-beam Ronchigram in which elliptically shaped moire fringes appear. The ellipses may be used to determine quantitatively the primary aberration, such as the coefficient of spherical aberration, coma, or astigmatism.
Lin
J A
JA
Hsu
J
J
Shiue
S G
SG