6 replies to this topic

[Oregon-raybender]

If you are interested in the latest information on composite

mirrors (IE. lite weight). The process is getting better.

You can check out the publications on this web site.

 

Maybe it won't be long until cheap enough for mass

production. Should be interesting to watch in the

coming years.

 

Starry Nights

 

https://www.composit...om/publications

 

 

 

[TOMDEY]

Nice - Looks legitimate! Where I worked we were working on such with eventual (recently!) good results in very large sizes.. Keep in mind that these are still extremely expensive. The intent is ultralight weight, not cheap cost. For aerospace applications, this makes sense. For cheap hobby mirrors... the process is actually far more picayune than plain glass. The biggest remaining problem is long term wavefront stability. This may well be why they are pushing the adaptive dimension, which adds huge complexity, rather than just making a rigid perfect mirror to start with, that will passively hold its figure long term. Time will tell.     Tom 

[careysub]

Sort of like aluminum-beryllium mirrors. Yep, ultra-light weight and a real thing, but no hobbyist is buying any.

 

We are never getting mirrors cheaper or more convenient than glass/quartz ones. For lighter weight look to someone doing more sophisticated glass blanks -- meniscus, cellular casting, sandwich, conical and so forth.

Edited by careysub, 07 March 2025 - 10:04 AM.

[Oregon-raybender]

The mirrors are honeycomb type, epoxy base I believe. Not AL-bery.

The surface replicated from a master. 

 

Back in late 70's we were able to make 1 to 1/2 wave flats replicated

on AL blanks, 1-3 inches. The issue was the release agent.

They were coated first and then glued to the substrate.

Fun project, it looks they improved it quite a bit.

 

Starry Nights

[JohnH]

I have two older mirrors from Embedded RF.

This is from before why they sold all their patents and intellectual property so I believe HexTech

It has truncated conical roundels in the back of the mirror face effectively removing somewhere around 60 to 70% of the volume and weight of glass and it has a very nice F 4.5 Curve cast into it

[MeridianStarGazer]

If you are interested in the latest information on composite
mirrors (IE. lite weight). The process is getting better.
You can check out the publications on this web site.

Maybe it won't be long until cheap enough for mass
production. Should be interesting to watch in the
coming years.

Starry Nights

https://www.composit...om/publications

Will graphite mirrors ever be made? Very low CTE, very high stiffness to weight ratio, not that expensive, and maybe less work to grind and polish.

[Lagrange]

Will graphite mirrors ever be made? Very low CTE, very high stiffness to weight ratio, not that expensive, and maybe less work to grind and polish.

I don't know if graphite has been tried but silicon carbide has been used for mirrors as well as building entire telescope structures - usually for space applications where weight is critical.

 

The production method enables complex forms to be machined before final sintering turns the compacted SiC powder (with a binder) into a solid mass. Mirrors can also be manufactured in segments and the "brazed" together if very large optics are required.

 

The image below shows an experimental 630mm mirror that weighed just 6.2kg.