The RASL optical tube assembly also presented additional
design and fabrication requirements including high strength to withstand the "G" loading
of the aircraft and operation in any attitude. The mirror supports have to support the mirrors and
maintain collimation (optical alignment) over the various "G" loads, directions, and temperatures.
The wide temperature range requires the mirror supports and the mirror optical spacing to be fully
passively temperature compensated.
DFM Engineering has used Invar (a metal with very low temperature expansion coefficient) spacers
on most of their telescopes to minimize the focus shift with temperature changes. The RASL telescope
required Invar spacers and additional temperature compensating elements to meet the focus stability
requirement. Additional information on focus stability may be reviewed at "Performance
Requirements for the Internet Telescope".
NASA will soon be integrating the RASL telescope with the Nd:YAG laser transmitter and the multi-channel
filter-detector receiver. Laboratory tests and demonstrations will be followed by installing the
RASL telescope into the airplane.
For more information on the original requirements and design specifications from NASA, please visit
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Performance Requirements for
the Internet Telescope