Jean St. Thomas and I had a very gratifying working association for more than two years during the mid-fifties. St. Thomas was obsessed with the desire to do something about the problem of codification. It was apparent that he had a keen insight into the re-quirement and the problem. He made serious attempts to verbalize the nature and the scope of the problem in various papers. St. Thomas reflected later that his early proposals were "premature, incomplete, and unsuitable for indexing." This statement of construc-tive self-criticism was presented by a man who is earnestly involved with an unquenchable desire for a workable solution. St. Thomas probed, discussed, revised, re-considered and has currently presented a base from which a system of codification can now be initiated. I was requested by the Society of Photographic Instrumentation Engineers to review and introduce the revised work and to add my endorsement. I am delighted to comply: The codification of Photo-Optical Instrumentation Engineering under the Dewey Decimal System, as proposed by St. Thomas, is the result of the analysis and selection of a currently recognized classification system to serve as the structure from which an immediate and workable solution to the indexing of "hardware" can be accomplished for the systematic storage and retrieval of information. The practical experiences gained from other serious attempts to codify the field has been considered in the St. Thomas proposal. The accelerated growth of technological knowledge is creating an ever increasing demand for the service of storing and retrieving PhotoOptical Instrumentation information. It is recommended that the proposal receive the immediate attention of the responsible parties who are in the authorized position to initiate and execute a plan of action.

Diffraction by opaque and transparent particles which present a circular cross-section to a collimated quasi-monochromatic beam of light is discussed theoretically and experimentally. The plane in which the diffraction is recorded is at a sufficient distance from the plane containing the particles for the ap-proximation of Fraunhofer diffraction to be made--but not in the focal plane of a lens. The intensity distribution in the Fraunhofer pattern consists of several terms but the dominating one involves the Airy pattern of a circular aperture multiplied by a sine function, which is independent of the size of the particles. This term, which represents the interference between the light diffracted by the particle and the coherent background, may be removed by spatially filtering the diffraction pattern formed in the focal plane of a lens. A second lens re-transforms the remaining pattern to produce an image of the original particles. The film planes are set at known distances from the image plane so that Fraunhofer diffraction patterns of the individual particles are recorded. Using a pulsed ruby laser as a source, diffraction patterns of moving particles have been photographed. The results obtained indicate that this technique should prove quite useful in the measurement of small particles, aerosols, fog droplets, etc.

The first laser was announced about four years ago. Since then, many of us have watched the progress of laser tech-nology with particular interest in the applications in which this new device might prove itself either superior to pre-sent devices or, hopefully, able to perform new tasks. Out of this continuing exami-nation will come the new applications which will establish the laser as a useful tool for the scientist and the engineer.

Since many of you attending this session of the 8th Annual SINE Technical Symposium may not be familiar with the activities of Korad Corporation, I think it would be useful, as an introduction, to briefly describe our organization and products. After being formed in October, 1962, Korad became a subsidiary of Union Carbide Corporation. Dr. Theodore H. Maiman, who invented the ruby laser, is the President of Korad. The principal objective of the company. is to develop and manufacture laser de-vices and associated electro-optical components. The company's work with lasers, encompass many fields including materials research, spectroscopy, laser flashlamp development, semiconductor lasers, as well as a full line of solid state crystal lasers..