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262 F I R E R E S E A R C H An interferometer is described which is based on two shadowgraphs minutely displaced with respect to each other The apparatus, designed for fire research, allows the display of large test areas where the use of focusing optics becomes impractical The present system, as confined by the dimensions of the laboratory, provides a field 3 f t m diameter with sufficient illumination for exposures shorter than 0 04 s for still or motion pictures, using commercially available cameras and films A straightforward calculation suggests that a 1 W laser would allow coverage of a field 30 f t m diameter The apparatus is simple and rugged enough to be potentially useful for field studies of fires, given a sufiiciently large screen Some illustrations of apphcations and a discussion of its theory are included Baev, V. K . , Klimchik, G. V. and Yasakov, V. A. (Novosibirsk, USSR) "Optical Method of Measunng the Concentration in Axisj-nimetrie Gas Jets," The Physics of Combustion and Explosions {Fizika Goreniya i Vziyva) 8, 138 (1972) (in Russian) Sections: N , G Subjects: Schlieren techmques, Optical studies, Composition measurement AbstractâL Holtschlag The aim of the authors was to develop the "knife-and-sht" variant of the Schheren method to the point where the results from this method would not only yield the qualitative behavior of concentration in a flow, but would also correspond qualita- tively to the expenmental data obtained by other methods An image of the in- homogeneity is obtained using a Toysler instrument, the jet is measured photo- metrically The boundary and axis of the jet are obtained from the curve of film blackemng The angles of deflection are determined from a calibration curve, which gives the blackemng as a function of the angle of deflection Then the mdex of refraction is cahbrated, and a formula is given for calculating the bulk con- centration from the distnbution of the refractive index The method was used to measure the concentration in a jet of hydrogen issmng into static air Maxwell, F . D. (Pacific Southwest Forest and Range Envuxinmental Station, Forest Service, U S D A ) "A Portable IR System for Observing Fire Through Smoke," Fire Technology 7, 321 (1971) Section: N Subjects: Fire detection, IR detectors, Smoke, Fire mapping Author's Conclusions
