AUTOMATIC PLOTTING EQUIPMENT 
By 
1 
Morris M. Birnbaum, President 
And 
Phil M. Salomon, Staff Consultant 
IMPRO CORPORATION 
Pasadena, California 
One of the earliest attempts at automatic contour plotting is 
described in U. S. patent No. 2,283, 226, issued to H. B. Porter in 
1942 (1). Using a projection type stereoplotter, with each projector lamp 
strobed, he scanned the stereomodel with a nipkow disk-multiplier photo 
tube combination hung between the projectors, looking for points of equal 
light intensity from each projected diapositive. Since there are an in 
finite number of points in the stereomodel where the light intensity from 
each diapositive is identical to the other, no successful equipment was 
built. 
In 1950, the Bausch and Lomb Optical Company of Rochester, 
New York, under contract to the U. S. Army Engineer Research and De 
velopment Laboratories, undertook investigation of automatic contouring 
equipment (2) . Bausch and Lomb engineers used a multiplex stereo 
plotter and replaced the plotting table with a nipkow disk and two multi 
plier phototubes, one for each diapositive image. The attempt was made 
to measure the phase shift between the video signals from each diaposi 
tive. Excessive noise in the electronics system, and the difficulty with 
video signals not being tractable sinusoids, prevented the system from 
operating. 
Pickard and Burns, Inc., of Needham, Massachusetts, con 
tinued the work of Bausch and Lomb. The projected stereomodel was