The principle of anti-peeping glass in daily use, such as building windows, car windows,,,

Peep-proof glass is a kind of one-way mirror, also known as single-side mirror and atomic mirror. But in fact, it is a "double mirror" with no difference in optical properties. Since there is no difference, why are the observation effects of the two sides different? In fact, the principle is very simple. The effect of single-sided reflection is caused by the different ambient light intensity on both sides of the mirror. Next, we will explain the reasons for the formation of one-way perspective by analyzing the manufacture and optical path of the mirror. In manufacturing, the glass surface of a single-sided mirror is coated with a thin silver film or aluminum film, which is different from ordinary mirrors. This film does not reflect all the incident light, but allows half of the incident light to pass through and the other half to be reflected back. In modern times, high-strength PVB glue is sandwiched between two layers of 6mm toughened glass coated with nano-Cr-Al (glass consists of two layers, each layer is toughened glass coated with nano-Cr-Al). In this paper, the coated single-sided mirror is taken as an example for analysis.