: : : two chips were expoyied back?????

: Am I to understand that you put epoxy on the glass to put some small chips bac onto the mirror? Yes, the epoxy will outgas and cause problems. The coater should have asked you about the problem if it was visible. It's better not to epoxy anything onto the mirror before it's getting coated. If the chips you are talking about just little 1/4" or smaller chips off of the edge then they shouldn't have been epoxied on as thier distortion of the image is insignificant to the mirror. You should let the coater know of any strangeness that you may have done to the mirror beforehand like an epoxy job. Bet that the haze is next to the epoxied areas. Send the mirror back to the coater and let him know what you did and to please fix it. : If the chips are large, you might as well call the mirror a poor mirror and just live with it. : I don't know what else to tell you but the coating job is bad and it may have been the epoxy, especially if the epoxied area is where the haze and other problems are.

Hi Robert, thanks for the response. The chips were at the edge and actually under cut the surface. the glass is BCV which is layered and the first layer chipped down and inwards. This was expoyed about 6 months ago. The bronzy hazy area is over the centre mostly, about 6" diameter and is not by the actual chips, although the gas may have settled on the mirror face. Withen a couple of days in a 2" diameter area, many small pinhole bubbles devoloped. The coater is going to take the mirror back and perform a more rigorus cleaning and an outgassing cycle.

Thanks for your help.

Also, with a start test with about 1/16 of the mirror edge masked the inside and outside images are identical, with out the mask the outside is sharp while the inside is fuzzy. I am assuming samll TDE left, which does not show up on ronchi and foucalt test. I can live with that. What I have noticed is a slight astigmatism. not noticable when star image is expanded a bit on either side of foucus but at close to foucus you can see a oval shaped image that reveres direction when changing from inside foucus to outside. You would not notice this if you were not looking.

Will this have much impact on the image and is this strictly an error in the mirror or is there possible collimation corrections needed which can contribute to it.

Thanks

Gerry

• Re: Alumnized mirror failure - bobmay - September 9, 1999 - 19:02 UTC