Timeline for Why are segmented mirrors lighter than monolithic mirrors?
Current License: CC BY-SA 4.0
10 events
| when toggle format | what | by | license | comment | |
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| Sep 25, 2023 at 12:04 | comment | added | Darth Pseudonym | The only wording you complained about was "take a block of glass", and now you're claiming the answer asserts that you need to "remove more material" (which it never said). So what exactly is your complaint? This answer is not really about the production method, it's about the relative thickness of the inner to the outer edge. | |
| Sep 25, 2023 at 0:12 | comment | added | leftaroundabout | @DarthPseudonym yes but the point is, you would not need to remove more material (like this answer asserts) if you spin-cast the entire mirror in one piece and fine-shaped that, than if you spin cast the individual segments and shape all of them. | |
| Sep 24, 2023 at 23:48 | comment | added | uhoh | @leftaroundabout Indeed! Making the mirrors for the Giant Magellan Telescope at the University of Arizona and also MIRROR LAB | Preparing for Casting GMT's Mirror 6 from the question Why telescope mirror glass shipped as randomly broken chunks of a constant size in cardboard boxes? | |
| Sep 23, 2023 at 11:36 | vote | accept | David Cian | ||
| Sep 23, 2023 at 11:36 | |||||
| Sep 22, 2023 at 17:50 | comment | added | Darth Pseudonym | Spin casting just gets you an approximately parabolic hollow in the top surface of the mirror to save time. It's still a huge block of glass that you have to shape. | |
| Sep 22, 2023 at 16:24 | comment | added | leftaroundabout | "When creating a mirror, you need to take a block of glass..." no you don't, you start by casting it in an approximation of the desired shape. en.wikipedia.org/wiki/Spin_casting_(mirrors) | |
| Sep 22, 2023 at 15:32 | comment | added | Darth Pseudonym | If you're going to do some complicated cutting on the mirror to remove material from the back, why not segment it while you're at it? And if you're going to do that, you should just plan it from the start and make a composite mirror instead of casting a big huge mirror and then cutting it apart. | |
| Sep 22, 2023 at 14:49 | comment | added | planetmaker | One probably could. Though that means to touch the optical side with whatever tool you need to shape the rear side - something you don't want. still... the risk is increased. And you will still need the support then as you need for a segmented mirror - and you have the much bulkier mirror itself which is much more complicated to get right during production and handle for installation (but you know that) :) | |
| Sep 22, 2023 at 14:27 | comment | added | David Cian | So this assumes that you only remove material from the reflecting side of a cylinder. Could you not also remove material from the other side? | |
| Sep 22, 2023 at 12:50 | history | answered | planetmaker | CC BY-SA 4.0 |