title: Null testing in a modified scatterplate interferometer.
abstract: By using the scatterplate interferometer in a noncommon path mode, it becomes possible to cancel test aberration. The techniques for fabricating such a scatterplate are very similar to those found in holographic interferometry. A null test of a 20-cm diam, f/3 parabola is described.
authors.forename: L F
authors.initials: LF
authors.lastname: Rubin