I made a final optical correction on the frontplate and finished three more primary mirrors for three more instruments. During tests the first front corrector showed some inhomogeneities in the material, not visible in focus but detectable in out-of-focus images. This was annoying and unacceptable and I ordered new blanks from another supplier. I just started polishing the first of three new front correctors. The very first one (the one with the material defect) is now being AR-coated and will be back in a few weeks from now for further testing on ghost images and contrast. This coating needs to be flawless and effective over a wide wavelength range and therefore the price of such a coating is astronomical unfortunately.
Mechanically we also make progress, but innovations take time obviously. The new focuser is still not finished yet. Just before sending the plate to the coater I got a chance to test the entire system together with a new non-rotating helical focuser (see image below) on the same earth-based object shown earlier. I'm very sattisfied with the views and look forward to have real first light on the night sky :-)
