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The ARES device utilizes a scanning pattern made up of crossed diagonal 
lines as shown in Figure 7(d). This scanning pattern lends itself to both 
viewing and parallax sensing requirements and is relatively simple to produce 
electronically. Owing to the crossing of orthogonal sets of parallel lines, 
each set of lines tends to obliterate the structure of the opposite set giving 
an image with faint woven-silk texture. Such images are distinctly more pleas 
ant than TV-type images of equivalent resolution but, unfortunately, require 
considerably more video bandwidth for their production. 
From the standpoint of parallax detection the crossed diagonal pattern 
offers the following advantages: 
(1) The motion of the scanning spot in mutually perpendicular directions 
permits distance measurements to be made in the image directly from time meas 
urements and in two orthogonal axes. Therefore, X and Y parallaxes can be 
detected without pattern reorientation. 
(2) Each point in the image is scanned successively in four directions, 
along two perpendicular axes giving four permutations of the image information 
and eliminating errors arising out of delay displacement. 
(3) The scanning pattern is produced simply by the application of tri 
angular waveforms of nearly identical frequency to the X and Y deflection 
systems of the cathode ray tube. 
(4) All areas in the image are given equal weight in the determination 
of parallax, and the scanning velocity is constant at all times without re 
traces; therefore, comparatively simple correlation circuitry serves to detect 
parallax and to derive therefrom the various error signals required for trans 
formation correction. 
In its present form ARES utilizes a square raster with 510 lines to the 
diagonal. A repetition rate of 30 frames per second with single interlace is 
employed. 
The crossed diagonal raster has proven to be quite satisfactory and pro 
duces a picture pleasing in appearance and capable of being viewed over long 
periods of time without discomfort. The pattern also appears to yield better 
recognition of small detail than a TV raster of the same number of lines. 
TRANSFORMATIONS 
Zero-order transformations or image displacements are produced by shift 
ing the rasters on the faces of the flying spot scanner cathode ray tubes. 
Displacement of the images in the X and Y directions is also provided by 
motion of the right-hand image by means of transport servo motors. Displace 
ment of the rasters is used to provide rapid image movement, the servo motors 
making their adjustments relatively slowly in response to the displacement of 
the raster. In this way, a rapid-acting system is obtained by virtue of raster 
displacement, whilst the servo motors avoid the necessity of large raster dis 
placements and permit the optical and electron-optical systems to work over 
relatively narrow field angles, thereby improving image resolution.