V. Ronchi, Testing of Optical Systems. Translated from the Italian by V. V. Antonov-Romanovsky, edited by S. I. Vavilov. GTTI, 1933, p. 102.

Ronchi’s small book contains a concise exposition of methods for investigating the quality of images produced by optical systems. After a very brief—and therefore insufficient—theoretical introduction, recalling the foundations of the diffraction theory of the image and the geometrical theory of system errors, the classical methods of Galileo, Foucault, and Hartmann are set forth; then follows the main part of the book, devoted to the description of numerous interferometric methods. The essence of each of these methods is presented in the simplest possible form, but always accompanied by formulas corresponding with sufficient accuracy to the observed phenomena and therefore quite suitable for practical application; as is known, the exact theory of all these phenomena is very complicated. Of particular interest is the main content of the exposition itself, which is a collection of the author’s own works published in not readily accessible Italian editions.

For persons engaged in practical methods of testing optical systems, a concise critical comparison of the existing diverse methods is of undoubted interest; some little-known methods may find wide application in the mass testing of systems in factory laboratories. Thus, for example, one of the author’s methods, almost coinciding with Lénouvel’s method, is undoubtedly very convenient for the rapid evaluation of a large number of similar photographic objectives, as has become clear in practice. The extensive material contained in the book, and the author’s numerous critical remarks and comparisons, may arouse in persons working in this field an interest in comparative investigations of various methods and give rise to new combinations alongside those classical methods that have already been adopted by our specialized laboratories.

Since much of what is discussed in the book can be carried out by relatively simple means, provided that one has some experimental skill and a taste for this kind of work, the book may also be useful to those persons who, while not working in special laboratories, nevertheless have at their disposal some set of apparatus and instruments in various kinds of physics classrooms and teaching laboratories. One may hope for such an expansion of the circle of persons who might be interested in the book because the optical phenomena considered by the author, in addition to their immediate practical significance, are interesting in themselves, as particular and rather complex cases of interference and diffraction; the study of these phenomena may in any case be placed alongside the numerous particular investigations with which experimental physics was occupied during the period of development of its methods and accumulation of facts.

The translation gives no cause for criticism; the appearance of the edition makes a favorable impression; the reproductions of very delicate photographs are, on the whole, satisfactory and in any case better than is often the case.

A. Tudorovsky.