Testing the polished surface

In this video I describe my method for testing a fine ground pyrex substrate to ascertain whether fine grinding has been completed. This is necessary in order to determine when to move on to the next stage, figuring the surface of the mirror.

A surface that is not properly polished will not hold a reflective coating and will not be very useful as a telescope mirror.

This video will help you in determining whether your mirror is indeed fully polished.

Category:

Science & Technology

Tags:

• Amateur telescope making
• mirror
• telescope
• polish
• foucault
• optical flat

[hla27b]

Very informative videos. Keep up the good work Francis.

[foreilly1958]

@hla27b THank you!

[promethium144]

Great vid :) looking forward to the vids on figuring i'm gearing up to make my first mirror soon theses vid s have been a great inspiration :D

[foreilly1958]

@promethium144 How's the telescope mirror coming along?

[promethium144]

unfortunaty finances are tight at the moment but will hopefully be able to get things going in the new year i plan to document everything so will keep you tuned in :)

[foreilly1958]

@jamieball I either go to a mirror class in Washington DC where they have a vacuum chamber and coat the mirror there or I send the mirror to a commercial coater in Skokie Illinois for coating with a proprietary metal that he calls beryl. The coater is Clausing Optical coatings. You can reach them through Google. Best regards, Francis J. O'Reilly

[foreilly1958]

@wannab009 I either go to a mirror class in Washington DC where they have a vacuum chamber and coat the mirror there or I send the mirror to a commercial coater in Skokie Illinois for coating with a proprietary metal that he calls beryl. The coater is Clausing Optical coatings. You can reach them through Google. Best regards, Francis J. O'Reilly

[wannab009]

@jamieball I was wondering the same thing can't find much information on it by googling it, all i find is grinding procedures

[jamieball]

Yes, I think there are some mirror grinding seminars nearby it is just a matter of me going to one. One more question, After you have grinded and polished the mirror, how do you apply the reflective layer?

[foreilly1958]

It is a good feeling. I hope that you will share it sometime soon.

Best regards,

Francis J. O'Reilly

[jamieball]

Interesting, It must be awesome to use your own grinded mirror and have it perform well. I bet there is an immense feeling of satisfaction..

[foreilly1958]

I have made a 12.5 inch (318 mm) mirror. I am also working on another as well as two flats of the same size. I may go larger, but weight and portability become factors.

Francis J. O'Reilly