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projecting on mirrors
posted by Flash Light (lightart@flash.net, www.Flash-Light.net), 27.01.2004, 07:23
Let's begin with the difference between an ordinary mirror and a front surface mirror. An ordinary mirror is made with an ordinary sheet of glass or plastic. A reflective coating is applied to the back of the sheet. The glass or plastic protects the coating from being scratched, etc. If you project on an ordinary mirror, you will actually get two reflections. A faint one from the front surface of the glass or plastic, and a brighter one, from the reflective coating. The two images will be slightly displaced from each other due to the distance between the front surface and the coating. Distortions in the glass or plastic will cause distortions in these images.
A front surface mirror is designed to avoid this. Ideally it is plate glass. The surface is polished to be perfectly flat and remove all distortions. The reflective coating is applied evenly to the front surface. There is no protection against it being scratched. However, it will yield only one reflection, which should have a minimum of distortion.
Is the front surface mirror really necessary? Depends on what you're projecting, and what you're projecting it onto. If you're projecting abstract patterns onto the costumes of a group of dancers, it probably won't make a difference. If you're trying to project a detailed high resolution image sharply onto a flat screen, it probably will. I suggest you try an ordinary mirror first, and if that's not acceptable, invest in a front surface mirror.
With either type of mirror, I agree with Sally that the angle of incidence equals the angle of reflection. I hope this helps.
complete Thread:
 projecting on mirrors
from Lillian Ball on 20.11.2003 at 13:51  projecting on mirrors
from Flash Light on 27.01.2004 at 07:23
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