How are Mirrors Made?
When most people use the term “mirror,” they are referring to what is known as a plane mirror. A plane mirror takes the light that hits it and reflects it back. Mirrors used for common consumer purposes are of this sort. A mirror is essentially a highly reflective surface. The sorts of mirrors one sees on walls or in bathrooms are of a type known as back-silvered mirrors. This means that the reflective surface–in most modern mirrors this is aluminum–is viewed through a thin layer of glass. The glass protects the aluminum from scratching and bubbling, but also distorts the image somewhat. Early mirrors were created by simply polishing a suitable substance until it became highly reflective. Neolithic mirrors have been discovered, made by grinding down obsidian rocks and polishing them to an incredible sheen. These mirrors have remarkable properties, allowing even subtle details to be clearly seen in their reflections. To make a Neolithic mirror, one need first find the right stone–ide
If you mean concave telescope mirrors… Basically you rub one piece of glass (Mirror Blank) on top of another (Tool) with abrasives (Carborundum) and some water between them. As the top mirror moves over top of the tool, the center of the mirror blank is worn more than the edges, basically because the center remains in contact with the tool and the abrasives longer than the edges. This forms a concave surface. After you have a rough curve figured, usually tested with a cardboard template, the mirror is polished somewhat, dampened (with water) and put into a mount. Then one uses something called a Focault Tester to see a greatly magnified shadow picture of the mirror surface. Without going into a great deal of detail, there are a series of shadow possibilites that tell you if you’re mirror is ground correctly. If it’s not (and it won’t be the first time, trust me), then you put the blank back on the tool and keep going until the curve is correct. Then you polish the mirror, usually wit
Compton’s: Bingo! Described in detail the polishing of the glass and the process to deposit silver salts. Encarta: Bingo! Provided detailed description of mirror making methods throughout history. Grolier: Bingo! Described the earliest methods to modern processes. World Book: Very brief answer. States that “most mirrors are made by putting a thin layer of silver or aluminum onto a sheet of high-quality glass.” Excite! Great answer found at Dr. Universe, but to a slightly different question – “How do mirrors work?” Numerous other articles on how to make telescope mirrors provide details. • How does general anesthesia work? Compton’s: Bingo! Explained that anesthetics can depress the activities of the central nervous system and block the communication of nerve cells. Encarta: Partial answer. Detailed article on anesthesia, including its history and methods of administration, but provides no specific details about how it works. Grolier: Bingo! Explained two theories, one involving a neuro
