The Electrooptical Shutter—its Theory and Technique

This paper records a development in the design of the single cell type of electrooptical shutter together with a theory describing its action. Part I. gives a description of the shutter together with a method of observing simultaneously two stages of the phenomenon being studied. Part II gives the theory of shutter action. A condensed summary of the physical optics is followed by a development of the electric circuit theory which gives the manner of closing of the shutter when the leads to it are fairly short. The theory is illustrated by a series of numerical examples based on typical experimental conditions which show the effect of varying each controlling factor. The times required for closing (90 to 100 percent transmission) are of the order of 4\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}9}$ sec. under favorable conditions. The necessity for a Kerr cell of small electrostatic capacity is shown. Part III gives three groups of experimental data which were obtained with the shutter in a study of spark breakdown: one indicates the time resolution attainable; another gives the total time lag in closing; and a third gives the change in this lag with certain conditions. The information of the second group combined with the theory yields the rate of fall of voltage across the controlling spark gap (static breakdown), a typical value being 14\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}9}$ sec. to fall to 20 percent of the initial value (76 cm Hg, 5 mm gap). The theory and experimental data are found in complete agreement. An improved method is given for the determination of the correct damping resistance in the shutter circuit. Part IV gives a description and the factors considered in the design of the Kerr cells developed in the present study, also the essentials of the technique for their proper use.