The utilization of optical alignment instrumentation in the assembly of certain large telescopes provides a convenient means for installing and calibrating these massive systems in the observatory. An experiment was performed during the factory acceptance test of a 1.22 m (48 in.) aperture Cassegrain to determine the accuracy which might be realized in practice. Scatterplate-interferometry and Hartmann tests were used with a 1.24 m (49 in.) optical flat to quantify laboratory performance. The results were impressive. The telescope alignment not only met the one-quarter wavelength peak-to-peak specification but also demonstrated that this type of calibration procedure can be performed on site, requiring a minimum of time, equipment and operator experience.
J. B. Houston, Jr.,
Bruce H. Walker,
David W. Dodgen,
"An Alignment Technique for Compound Reflecting Telescopes," Optical Engineering 12(5), 125161 (1 October 1973). https://doi.org/10.1117/12.7971653