-7- 
Figure 4.- Table top (section). 
The operation of flying spot scanners has been described in detail else 
where 1 and is not dealt with here. In the interest of clarity, however, a 
schematic of one optical system is shown in Figure 5, and it will be seen that 
the scanning raster on the cathode ray tube in the lower part of the figure 
is imaged by the objective lens onto the lower or emulsion side of the dia 
positive stereogram on the transport. Light passing through the diapositive 
is collected by the condenser lens and directed toward the multiplier photo 
tube in the upper part of the figure. The various apertures shown serve to 
exclude extraneous light. 
OBJECTIVE LENS 
Figure 5.- Optical system (schematic). 
L Hobrough, G. L.: "Automatic Stereo Plotting." Photogrammetrie Engineering, 
25(5), December 1959.