Simple Drum Camera

A somewhat unusual approach is encountered when high-speed motion picture cameras of the Hycam type are used as a streak camera. This is accomplished by filming through the camera s viewfinder which bypasses the prism system that normally cuts up the scene into frames or pictures. After nearly one-fourth of the film has run through the camera the voltage-controlled rate of film travel is reasonably steady and can be used for velocity measurements. 

Variations in film travel speed are easily ascertained by the millisecond markings imprinted along the edge of the film as the camera runs. Two advantages are gained by this technique one, the camera can be set to initiate the subject action at any pre-determined delay and two, since the film never is exposed again to 

Frequently it is as necessary to cut off the illumination as quickly and precisely as it is to turn it on. Internal electro-shuttering, such as accomplished with the Faraday and Kerr cells, can be synchronized with the camera and event exactly as needed (Ref 17). However, as mentioned1 above, cameras such as the Beckman/ Whitley framing camera as well as most continuously writing streak cameras, run the risk of incurring double exposures (Ref 13). 

This is due to the image re-writing propensity of the rotating mirror and many drum-camera systems. Small auxiliary detonating charges can be used in a number of ways to block off light and image exactly when required. 

Explode a small charge in contact with a block of glass in the image path. The internal multiple cracking caused by the charge makes the glass effectively opaque 

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