Of whether the glass is to stress , or not depends, whether he can manage to do him a good mirror. There are those who argue, that the stresses in the glass in no way interfere, But I strongly advise against working with glass poorly relaxed. Unluckily, the album from which I tried to do my first mirror had stress and could not even do it good sphere. Na nożu Foucault,and it looked, like I did during polishing “hill” the sphere, except that the center of this hill was not lying in the middle of the mirror but in the mid-radius. If the mirror can be seen performing at the time of the study some eccentrically decomposing inequality, This may be a sign, glass that has just stress. As far as glass type “float” usually a well-annealed, with other boards of unknown origin may already be different. So in order to avoid futile grinding and polishing, want to do a simple test for the presence of stress. For this purpose, the glass plate should be given x-ray polarized light, watching her at that time by the second polarizer, which must be rotated around the axis. If the disc still looks the same, that is to say , it does not have the stress. If we respect each other in different settings of polarizers , in the glass there is something resembling balloons with a cigarette, it is are areas of tension. Below is a schematic drawing of such a system to study the glass.
If you do not have at hand polarizers, such a test can be performed using the LCD display (np z laptop), which in this case is the source of polarized light, to watch a disc, use of glasses with a three-dimensional cinema, possibly other polarizing glasses, ie.: designed for anglers or drivers. It is easy to conclude, whether we are dealing with polarizing glasses, just watch the laptop screen by turning the glasses around the axis. If at some point the light reaching our eye from the laptop will be cut off then we are dealing with polarizing glasses. You can also perform such a test longer buying glasses- need to observe some source of light by two pairs of glasses, rotate relative to one another. Once we shut off the lights in any position, it is a sign that the two pairs of glasses are polarized, if, in spite of some glasses rotate relative to each other the intensity of light reaching the eye is fixed, it is a sign that at least one pair of polarized light is not. The following pictures show just such a “complicated” set of research, and a glass plate with detected using this set of stress
