Mirror question

[Rocket Pooch]

What's the difference between a PV measurement and RMS ?

My 12" is apparently 1/16th RMS
My 6" is 1/4th PV

What does that mean then?

[JohnP]

this might help mate......

http://www.oldham-optical.co.uk/Optical.htm

[Mike]

That has to be one of the worst designed websites I have seen for a long time.

[JohnP]

Lots of information though....

[RobertM]

That's a very interesting article John.

[Rocket Pooch]

Ok cool so my mirror is better than 1/16th rms (the ones I have seen measured seem to be 1/24+ RMS) so that's about 1/4 wave or better PV, good, actually the 6"  is 1/6th PV, excellent so they should both be very good.....