How do you grind glass for a telescope?
How do you grind glass for a telescope?
This prevents the edge of both pieces from getting too sharp then chipping. When people ask, “How do you make a telescope mirror?” my answer is usually, “You take two circles of glass and rub them together for a long time with sandpaper grit in between.” That is what you will be doing.
How are telescope mirrors coated?
Aluminum coating is done by Aluminum Coating in a high vacuum tank. Aluminum metal is evaporated from a wire near the bottom of the tank and coats the mirror which is being rotated at the top of the tank. A very thin SiO transparent coating is coated over the aluminum coating. The mirror never becomes hot.
How do you find the center of a telescope mirror?
Make a hole there, about 1/10-inch across. Alternatively, you could measure the diameter of your mirror and use a compass (set to ½ the mirror’s diameter) to draw a circle on a blank piece of paper — the pinprick of the compass point defines the centre of the circle.
When should you recoat a telescope mirror?
All telescopes have to recoat their mirrors every few years. Most telescopes coat their mirrors with a very thin layer of aluminum. The exceptions are the Gemini Telescopes, which recently coated their mirrors with silver.
How do you Aluminize a telescope mirror?
First, they strip off the old reflective coating, then prepare and polish the glass surface, and finally secure the mirror inside the large vacuum chamber metal tank for aluminising. The smooth glass surface is covered with a few grams of aluminium, spread out in a layer only 100 atoms thick.
What is the best way to grind mirrors?
The key to successful mirror grinding is randomness in stroke numbers and tool and disc rotation. Adding more randomness with a tile tool made from tiles that have been smashed with a hammer cant do any harm 🙂 Always work wet! Sprinkle some water on the grit before you start grinding!
Are spray silver coatings a good option for telescope mirrors?
Several forces have come together recently to make spray silver coatings an attractive option for telescope mirrors again, especially those 12-inches and larger in diameter: The cost of aluminizing has gone up, and for a large homemade telescope it can be the single most expensive element, especially if the coating is enhanced.
Is it OK to strip the aluminum from a telescope mirror?
“Telescope mirrors are delicate, precision optics and shouldn’t be touched!” Mostly yes, but sometimes it’s not only ok, it’s the only way to proceed. Stripping the old aluminum coating is one of the times it’s ok – to create a new silver coating you have to get rid of the worn-out aluminum coating first.
How to make a mirror with tile tools?
Tile tools grind faster, and you can make 2 mirrors instead of one. Or you can share the costs of a mirror kit with a friend and make a mirror each. A tile tool is a disc poured from cement, with a layer of hard, porcelain tiles epoxied on it. Make it the same size as the mirror in diameter, 50 mm thickness is fine.
