Fast Multiple Frame Photography

Abstract

A new principle has been applied to the optical systems of cameras so that series of photographs can be recorded at high speed without complex equipment. A plate embossed with a large number of small lenses is used to dissect the picture into small elements. These are all recorded simultaneously on a plate, but each element is separated from its neighbours by a distance that is large compared with the size of the element. Many successive pictures may be similarly dissected and recorded on the same plate interlaced with the others. The displacement of successive images with respect to the plate need only be as great as the width of a single picture element. The displacement is produced by altering the direction in which light falls on the lenticular plate, and this alteration may be achieved mechanically or optically. Using the simplest mechanical arrangement series of 200 photographs have been taken at 50,000 per second of objects that are self-luminous or that are separately illuminated. In each picture there are 40,000 picture elements-a resolution of 200 lines across the field in each dimension. For transparence or silhouette photography mechanically moving parts can be entirely eliminated. The displacement of the picture elements for separation of the individual frames is achieved by movement of the light source. In some forms of the apparatus the source of light is the luminous spot of a cathode ray tube. Series of 200 pictures have been recorded at 200,000 per second. The exposure time and the rate of taking pictures can be independently controlled. Synchro-nization with the phenomenon is simple. In other forms of the apparatus a short trail of lead aiide was used as a moving source of light. Twenty pictures were recorded at 4.000,000 per second. The cameras can all be used to unscramble the composite record for slow motion viewing and for conventional printing of individual pictures.

It has been possible to construct simple apparatus which may be used in any one of the ways described. It is a versatile and powerful weapon for the attack of a wide range of physical problems.