a mark was made on an image point in one photo and transferred to the
conjugate image by again using one table as the "master" and the
second as the "slave." The two marks were then compared on the
monitor scope and the deviations determined. An accuracy of two
microns was obtained. The average measurement time per point required
in the automatic mode was less than 5 minutes/point.
Continuing tests will be made over the next several months to
complete the accuracy evaluation and to determine the extent and com
plexity of maintenance required and the long-term stability possible
with this type of an electro-optical mechanical system. Indications
are that the stability is very good. Fabrication of the equipment
was completed approximately two years ago. Since that time the
equipment has been operated more or less continuously while adjusting
the equipment and determining and correcting design deficiencies.
Only recently has it been necessary to disassemble the tables for
inspection, adjustment for straightness of travel, and cleaning. It
is difficult to separate maintenance difficulties found from the
design deficiencies encountered during fabrication and debugging of
the equipment; however, it is evident that an experienced maintainer
who is intimately familiar with the details of the instrument is
required.
CONCLUSION
The design, fabrication, and test of the Automatic Point Marking,
Measuring and Recording Instrument, by including in a single integrated
instrument the combined functions of automatic matching of conjugate
imagery and the precise measuring and marking of this imagery, have
made the first important step in modernizing measurement of photo
graphic coordinates. The instrument has also made this data link an
integral part of the automatic map compilation system. As new tech
nological advances are made, as reliability of electronic parts
improves, and as new design procedures are found, it is easy to
visualize in the near future a compact light-weight automatic com
parator available for every requirement.
