While I was doing some research about laser techniques, I came across this on youtube:
https://www.youtube.com/watch?v=8OfowgD4CT0
About 1:04:36 they come to the point: Recording phonograph cylinders made of polycarbonate - as reference recording. Using a westrex head, they put M.J. into the grooves, at 160 rpm and stereo.
Not sure, if anybody has posted this yet, but: Enjoy
BR,
Martin