In optical testing a Ronchi test is a method of determining the surface shape (figure) of a mirror used in telescopes and other optical devices.

Geometric Ronchi test, basic geometric and diffraction principles, application, sensitivity and limitations

Ronchigram (after Italian physicist Vasco Ronchi [ˈroŋki] [1][2]) is the convergent beam diffraction pattern [3] of a known object with features comparable to the diffracting wavelength. In the case of electron Ronchigrams amorphous materials are used.

With a Ronchi screen this would be the illusion of straight and parallel lines, or bars, filling the mirror from your viewpoint. Anything else would be an aberration of these incoming and outgoing spheres. At the edge the bars would run off of the mirror without turning or hooking.

Feb 29, 2016 · It's simple: the Foucault (knife-edge) test measures longitudinal (or axial) spherical aberration (LA), and the Ronchi test measure transverse spherical aberration (TA). Daniel Malacara's book Optical Shop Testing 2nd and 3rd editions …

an electron beam that can reveal atomic structure in vivid detail. The Ronchigram— its structure, etymology, and the physics that describes it—is puzzling to new microscopists yet requisite fo.

Jan 1, 2002 · The so-called Ronchi Test, a standard method for assessing the presence of defects in mirrors, lenses and other optical components, is re-expressed in a more general fashion in phase space, by means of the Wigner Distribution Function, which allows not only to reproduce the standard formulation of the test, but also to explore novel ...

diagram below. If the lines appear bowed outwards inside the ROC and bowed inwards outside of the ROC the mirror has a curve deeper that a sphere. It may be elliptical, parabolic or hyperbolic. As stated the Ronchi test is not quantitative, observing the curved bands does not enable us to say which conic section fits the mirrors surface.

Introduction to the Ronchigram and its Calculation with Ronchigram.com. Microscopy Today, 27 (3). Schnitzer, N., Sung, S. H., & Hovden, R. (2020). Optimal STEM Convergence Angle Selection Using a Convolutional Neural Network and the Strehl Ratio. Microsc. Microanal. 26 (5).

In constructing telescope mirrors, the Ronchi test procedure evaluates the quality of the surface figure and provides guidance on refining the figure. The ruled divisions in a linear encoder are in the form of Ronchi ruling, which provides the basic precision of the measurements.