Resolving power requirements for a good photograph -Rather than determining the resolving power of the lens as such, we must evaluate the performance of a system consisting of a target, a lens, an emulsion, and an observer.

A modified schlieren optical system was designed and constructed for a quantitative investigation of free-convection boundary layer temperature profiles. The differential equations governing convective heat transfer belong to the most difficult class of theoretical physics and have been solved analytically for only a few simple cases. Interference photographs, interferograms, obtained using the schlieren interferometer provide a means of circumventing the mathematical problem for many conditions. The photographic results, checked by using thermocouples, were used in evaluating the temperature distribution, the key to the solution of these problems. This paper reports the application of a modified schlieren system in determining the geometric configuration of the thermal boundary layer for free convection from a flat plate at various orientations with the horizontal. Included is a description of the optical and photographic methods used.

The success of optical cine theodolites in instrumenting the wide range of test requirements has led to the design of the K-400, a sixteen inch aperture, 2" accuracy, digitized instrument. It is designed to operate in a variety of modes with television, laser and infrared. The integral design results in higher sensitivity, long range video outputs, precise ranging and tracking with lasers and automatic tracking and radiometry in the infrared. Design characteristics and performance have been described.

A broad research program under the direction of USAECOM is in progress to investigate techniques and equipment characteristics suitable for automatically processing graphical data for military requirements. This paper considers a phase of this program, which is concerned with techniques and experimental test results designed to determine machine proficiency for automatic recognition and classification of military map symbols. For convenience of test, these map symbols are on glass slides, but the implication is that the technique is useful for automatically categorizing and symbolically recording any form of graphical data that can be displayed electrically or recorded on hard copy. Preprocessing methods used to reduce the complexity of the input data so that it can be more readily handled by the adaptive section of the machine are discussed. A description of the preprocessing technique is given.

SNELL'S LAW - n' = refractive index of the denser medium. n = refractive index of the rarer medium. i = ray angle with normal in rarer medium. r = ray angle with normal in denser medium.