What is the relationship between reflectance and transmittance?

A: Reflectance and transmittance have a reciprocal relationship (when absorption is ignored, reflectance + transmittance ≈100%). The reflectivity of ordinary glass is approximately 4%, and the light transmittance is about 92-94%. The AR coating reduces the reflectivity through destructive interference and accordingly increases the light transmittance. For instance, if the reflectivity drops from 4% to 0.5%, theoretically, the light transmittance can increase by approximately 3.5 percentage points. This is why AR films not only reflect less light but also are more transparent. Woowhead Guanfudun adopts vacuum magnetron sputtering AR coating, with a reflectivity of ≤0.5% (self-tested by the brand laboratory), and the measured light transmittance by SGS is 96.5% (Report No. SZIN2606001469PL01_CN), which is a typical manifestation of high light transmittance brought by low reflection. At the same time, the haze is 0.4%, ensuring that the scattering loss is also extremely small. The reflectivity of ordinary films is 3-4%, and the light transmittance is usually only about 90%.