[mmaimcal] Re: quarter-wave plates

[John Payne]

hi Steve, Yes I designed and built such a device around 10 years ago for the 12
m telescope. It was used quite regularly in mm wave polarization programs for
several years. It was tested extensively by Darrel and I am sure that he has the
test results. I would be most reluctant to recommend such a device for the ALMA
project although Darrel's opinion is worth more than mine on this issue. I am
pretty sure that it is about the same device as John uses as i remember we
talked about publishing something on it together.
                                    Best Wishes,
                                                 John.