Handbook of High Speed Photography - IET Labs, Inc.

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GR 1531 -P2
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Figure 5-13. System for generation of a multiflash burst.
All Flash Delay units are adjusted for equal delay.
Since the Flash Delay is uncalibrated, an oscilloscope with a cali
brated time base or some other precise timing device will be needed if
it is necessary to flash the strobes at precisely timed intervals. If
minimum delay between flashes is desired, the stroboscopes may be
connected to each other directly. The General Radio line of strobo
scopes may be interconnected directly via special cables provided as
accessories for the various instruments. Table 5-1 indicates what con
nectors are required for all possible interconnections.
5.4 TAKING A TYPICAL HIGH
SPEED PHOTOGRAPH.
To summarize and illustrate
the complete process of taking a
picture of a high-speed event, here
is a typical industrial situation: a
photograph of the spindle (Figure
5-14) of a "false-twist" textile ma
chine is to be made to study the
yarn as it passes around the trans
verse (horizontal) pin. The spindle,
which is 3/16 inches in diameter,
rotates at the rate of 250,000 rpm.
Figure 5-14. 3/16"-diameter
spindle of "false-twist"-
textile-machine. Speed,
250,000 rpm.
The required equipment is shown in Figure 5-15. A photoelectric
pickoff is employed because of the high speed and low mass of the
subject. The Flash Delay Unit powers the photo pickoff and permits
single-flash exposure at any desired position of the spindle rotation.
The second strobe, shown slaved to the first, may be used to increase
the total available light and to render a more balanced exposure. A
4X5 press camera with a 150-mm lens and 18-inch bellows extension
capability is used so that Polaroid test pictures and negatives may be
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