Because the strength of toughened glass is relatively high, and after being broken, the fragments will be broken into uniform small particles and there is no common glass knife-like sharp corner, so it is called safety glass and is widely used indoors and outdoors. Tempered glass is obtained by cutting ordinary annealed glass to the required size, then heating it to a near softening point, and then performing rapid and uniform cooling. After tempering, uniform compressive stress is formed on the surface of the glass, and tensile stress is formed inside, which greatly improves the performance of the glass. The tensile strength is more than 3 times that of the latter, and the impact resistance is more than 5 times that of the latter. It is precisely this characteristic that the stress feature has become an important sign to distinguish true and false tempered glass, that is, tempered glass can see colored stripes on the edge of the glass through the polarizer, and black and white can be seen on the surface of the glass. Alternate spots. The polarizer can be found in the camera lens or glasses. Pay attention to the adjustment of the light source when observing, so that it is easier to observe.