Mjs, that HP journal was a very interesting read. I've worked in several machine shops and with plenty of metrology type instruments (CMM/SLM inspection, etc), had no idea that it was part of one of those systems. I believe I misspoke calling them obsolete! My quick Google searches before impulsively buying it didn't show the laser heads for this system, which seem to still hold plenty of value.
Currently trying to convince myself that I don't need a laser interferometer. I don't need a laser interferometer....