Polishing things flat is the easiest challenge (but still not trivial, as you can see). Polishing things to a spherical curve is still possible for people who don’t devote their working lives to it. Amateur astronomers can polish their own telescope mirrors, for example, although the bigger they get and the better the ‘figure’ you want, the harder it becomes. The really tough thing is polishing aspheres. We used to buy high-quality (of order lambda/10), relatively large (>100mm diameter) off-axis paraboloids quite often. They cost thousands for smallish diameter, largeish f-number ones and tens of thousands as they got bigger and the f-number got smaller. I once bought an f/3 off-axis ellipsoid, 125mm dia, and that was £15k back in the 1990’s. The polishers need a constant temperature, extremely low vibration environment to do the interferometry, which is the only way they have of knowing when the optic is good enough. Our favourite polishers were and, it seems, still are based in a set of disused mining tunnels in the chalk near Kenley
They’ll have their hands full keeping him in one piece. He is not going to be Mr Popular given his former profession. Sadly, if somebody kills him he’ll be a martyr for the far-right and hard of thinking. This might just suit them too.
I was beginning to suspect that the wheels were about to fall off my impending speaker purchase, although I couldn’t really see why given how it had previously been going.
Anyhow it turns out that there is a perfectly innocent explanation and I should be sorted soon(ish)
), he will be dead within weeks.
