Mirror ¦ rorriM
Created | Updated Jun 8, 2003
Mirror | rorriM
In ancient times a mirror was a peace of magic. As you look in a mirror you see as if your eyes are behind it. You can see through the mirror but not what is behind.
Flat crystalline surfaces are rare. Polishing a crystal is a hard job. Imagine the first attempts to create a flat surface. The people must have admired ice and still, dark and reflective liquid surfaces in the early days.
Mirror:
A sufficient flat surface of material refelecting the required spectrum with enough energy to create an image.
Nowadays the most common mirrors are made by evaporating a metal on a near crystalline sheet of glass. Depending on the use, the layer of metal is te front or rear side of the mirror.
For common use the reflective layer is protected by a thick layer of paint. Unfortunately you can only use this kind of mirror on the rear side. The light will have to pass twice through the glass thus reducing the reflective energy. This is for most applications good enough, by increasing the illumination of the object the image becomes better.
More efficient use is of only the reflective layer self. The ambiant conditions must be observed as the reflective layer will evaporate. The loss of energy can be very close to none.
Alternatives are made with a metal or plastic base. The metal should have an near flat molucule grid on the reflective surface. The plastic base also mostly depends on the molecule structure of the surface.
Users and radio waves can do with a metal mesh smaller then the wavelength.
Users of infrared might have to use rather thick layers of metal and can not all use ordinary glass.
Users of light can do with a very thin layer of metal and a wide range of base materials.
Users of ultra violet and higher will have to use very flat surfaces and small atomic particles as aluminium or even smaller elements for use as reflective layer.
Reflector
Anything that not absorbes all light energy is a reflector. One very intresting property of a material is its color. Seen as a reflector you could say the color of an object is, the colors that do reflect. The colors that are not reflected are usually absored and partly retransmitted in a lower part of the spectum.
Some materials transform the color of absorbed colors to the visible part, these are called fluorescant colors.
Retroreflector
Mirror, build out of triplets of small mirrors at right angles. Alternatively if transparant materials can be used, a surface covered with pure tiny spheres, inner reflecting the radiation. Both types mirror the light to where it came from at small scale. By distorting the whole of an image, just the reflection of the light is visible.
In ancient times a mirror was a peace of magic. As you look in a mirror you see as if your eyes are behind it. You can see through the mirror but not what is behind.
Flat crystalline surfaces are rare. Polishing a crystal is a hard job. Imagine the first attempts to create a flat surface. The people must have admired ice and still, dark and reflective liquid surfaces in the early days.
Mirror:
A sufficient flat surface of material refelecting the required spectrum with enough energy to create an image.
Nowadays the most common mirrors are made by evaporating a metal on a near crystalline sheet of glass. Depending on the use, the layer of metal is te front or rear side of the mirror.
For common use the reflective layer is protected by a thick layer of paint. Unfortunately you can only use this kind of mirror on the rear side. The light will have to pass twice through the glass thus reducing the reflective energy. This is for most applications good enough, by increasing the illumination of the object the image becomes better.
More efficient use is of only the reflective layer self. The ambiant conditions must be observed as the reflective layer will evaporate. The loss of energy can be very close to none.
Alternatives are made with a metal or plastic base. The metal should have an near flat molucule grid on the reflective surface. The plastic base also mostly depends on the molecule structure of the surface.
Users and radio waves can do with a metal mesh smaller then the wavelength.
Users of infrared might have to use rather thick layers of metal and can not all use ordinary glass.
Users of light can do with a very thin layer of metal and a wide range of base materials.
Users of ultra violet and higher will have to use very flat surfaces and small atomic particles as aluminium or even smaller elements for use as reflective layer.
Reflector
Anything that not absorbes all light energy is a reflector. One very intresting property of a material is its color. Seen as a reflector you could say the color of an object is, the colors that do reflect. The colors that are not reflected are usually absored and partly retransmitted in a lower part of the spectum.
Some materials transform the color of absorbed colors to the visible part, these are called fluorescant colors.
Retroreflector
Mirror, build out of triplets of small mirrors at right angles. Alternatively if transparant materials can be used, a surface covered with pure tiny spheres, inner reflecting the radiation. Both types mirror the light to where it came from at small scale. By distorting the whole of an image, just the reflection of the light is visible.
