Recent applications of photoionization mass spectrometry are reviewed and advantages over conventional electron impact mass spectrometry are pointed out. The need for further development of the involved optical techniques and an application to space engineering are discussed.

Exploratory studies were conducted to determine the factors responsible for possible flexibility problems in glass fiber optics. Commercial glass fiber optic materials of known composition were employed. Such mechanical properties as tensile strength and modulus, Poisson's ratio and fatigue were measured. Single and multi-fiber materials were compared.

The development of a system for the photometric reduction of Lunar Orbiter video magnetic tapes to obtain high-resolution topographic information of proposed Apollo landing sites was initiated by the Mapping Sciences Branch at the NASA Manned Spacecraft Center (MSC). The task of system design, hardware development, and integration (begun in late 1965) was assigned to the Information Systems Division of MSC The Computation and Analysis Division provided analyses of the programs and the development and operation of the system. This paper describes the system, its operational features, the special analysis techniques involved, results obtained to date, and continuing investigations.

A method for determining the acceleration due to gravity is suggested. Two falling interferometer reflectors illuminated by a laser are used. The falling reflectors are separated by a AT and thus have a constant velocity differential, this generates a frequency linearly proportional to acceleration ( g = kf ) Thus, the metrology of measuring g is simplified by having g linearly proportional to frequency.

COMMENT: ACOUSTICAL HOLOGRAPHY Acoustical Holography has developed into a subject in its own right and separate conferences on this subject ar now held. The fourth such meeting will take place in Santa Barbara on April 10-12, 1972. ( This meeting will be immediately followed by a SPIE seminar-in-depth on non-destructive testing that will be held in conjunction with this Fourth International Symposium on Acoustical Holography.) In this column the proceedings of the first three meetings are reviewed to provide a background to the fourth symposium.