GV—72 PHOTOGRAMMETRIC ENGINEERING 
being developed with lower shrinkage characteristics, the field flatness require- 
ments become more stringent. 
And film analyzing equipment (readers) must have optical equipment which 
is equal in performance to the recording equipment. What value does a film 
have when the distortion has been kept to 1 of 19, if the lens on the film reader 
has 29 or 3% distortion and has to be refocused after the center has been read 
in order to read the edges? 
The fiducial marking systems, too, have to be well designed. The fiducial 
marker should be brought in through the objective lens, not laid down at the 
film plane, where notched aperture plates are used. If there is poor registration 
frame to frame, the x and y notches are practically useless. With the fast, fine- 
grained films the use of the beam splitter, fiducial marker system is plausible. 
It overcomes the objection of the lack of consecutive registration. 
A typical subject for the analytical treatments, discussed in Table I. is the 
electrical relay. A relay is selected because of the variety of phenomena that can 
be studied by its performance. Among the reaction studies are: 
(1) Operate time (9) Effect of temperatures and pres- 
(2) Release time sure on performance 
(3) Contact chatter (10) Effect of acceleration and decelera- 
(4) Contact arcing tion 
(5) Contact erosion (11) Effect of shock 
(6) Contact spring performance (12) Effect of vibration 
(7) Reset spring performance (13) Effect of corrosion 
(8) Stud performance 
In conducting the photographic phases for the tests outlined above, the proce- 
dures and methods of analysis may be summarized, as follows: 
(1) Operate time. High speed motion picture photography will be 
used to record the event. The electrical impulse time can be 
simultaneously photographed by adding a neon, or argon, lamp 
in the field of view, or a cathode-ray oscilloscope trace can be 
simultaneously recorded. A timing light is used to provide 
the time axis. The time difference between impulse and the 
movement of the armature and/or the closing of the contacts 
are read on a “film reader” or a “time and motion study projec- 
tor." (Quantitative and qualitative.) 
(2) Release time. Same as ‘“‘operate time.” 
(3) Contact chatter. “Close-up” high speed motion pictures are 
made. The timing light with 1,000 cycles will provide the meas- 
urements of gross chatter. A 10,000 cycle wave is better for fine 
chatter. This is put right across the making or breaking con- 
tacts and shown on an oscilloscope. This is recorded simultane- 
ously on the film as the picture is made. This can be both quali- 
tative and quantitative. 
(4) Contact arcing. Again high speed motion pictures are made. If 
they are enlargements of the subject, the flow of melted metal 
and the formation of pits can be observed. This is primarily a 
qualitative analysis. It becomes quantitative if the current 
across the contacts is varied and measured and plotted against 
arcing time, 
(5) Contact erosion. The high speed motion pictures made with 
macro-techniques allow a qualitative analysis of the flow of the 
molten metal while arcing is taking place. The quantitative 
measurements are made from time lapse pictures. These pictures 
would be taken with a stipulated number of operations occurring 
between each picture; for example, the pictures programming 
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