Would it be possible to create an optical grade mirror by simply polishing a sheet of high-quality aluminum? Do you think it worth the effort?

Aluminum oxidizes readily. Stainless is an option. FS mirrors are pretty cheap though.

>Aluminum oxidizes readily

very high quality telescopes use aluminium coated (and polished) first surface mirrors as their primary (concave) reflector. What is the material used on the first surface mirrors sold in this store and do we have a figure of the % light lost?

Yes aluminum oxidizes readily. But the oxide of aluminum is corundum (or ruby) so it creates its own very hard protective layer. The surface on telescope mirrors must have a protective coating to prevent this.

Here is an interesting aside: Did you know that mercury causes aluminum to oxidize at an alarming rate? It prevents the aluminum from creating this protective barrier. Here is a pic of aluminum that has been coated with mercury after one hour.

And here is a link to the article about this.

If you didn't know this already, now you know why mercury is banned on airplanes.

Most FS mirrors are Silver with an overcoat to prevent oxidization. Reflection is rated around 94% so count on around a 6%loss. This is not much considering the LCD panel is an 80% loss.

Kirk