10/07/2020
The traditional manual method is adopted to process the lager diameter parabolic and hyperbolic lens with BK7 (ZK N4 or Zerodur) material, use knife-edge instrument for test, with high processing accuracy, and the diameter can be within 900mm.surface accuracy could be less than 1/40 lambda.
https://www.opticreate.com/coaxial-off-axis-parabolic-mirror/off-axis-big.html