THE THEORY OF FREQUENCY RESPONSE CALCULATIONS One of the principal advantages that have come from optical frequency response theory has been the possibility of evaluating the frequency response curves, and therefore the image quality, from the constructional data of the optical system. Since the methods have to be equally applicable to, say, extra-axial images in very wide-angle systems, it was necessary to reconsider critically the Fraunhofer diffraction formula on which they are based.

An automatic system which can fully replace the operator of a photogrammetric compilation instrument has not yet been developed, a fact which is perhaps not surprising in view of the wide range of mechanical and intellectual skills required in manual compilation. However, systems which automate the more routine operator tasks of stereo-perception and plotting have been successfully applied to a number of instruments. This paper discusses the use of electronic scanning and correlation techniques for the basic terrain-sensing function required in automatic stereoperception. It also shows how the information sensed by the correlation equipment can be used by the stored-program digital computer of an analytical stereoplotter to automatically plot contour and profile manuscripts. The final sections discuss potential approaches for improving the automatic stereoperception equipment and expanding the role of the computer to improve system performance and further increase the degree of automation.

A simple and inexpensive device for the measurement of equivalent widths directly from spectrograms is described and the accuracy of the results is discussed.

Radiation pumping of a laser rod causes internal stress upon absorption of any of the radiation. An NBS scientist has developed a photographic technique to simultaneously record these stresses at two focal points, in order to determine the optical quality of lasers used for scientific and industrial research.