Quality of automotive lighting and difference

 Headlight reflector bowl made in China, the majority is not the shape of the computer-aided design, instead of using the molds from patterns directly from the molding product piracy For more details of things, very few manufacturers have a real in-depth study. For headlight lamps, a final type of light is not only dependent on the design of the reflector, further comprising a lens portion (the lights front portion of a transparent glass or a polyester cover). This both appearance completely imitation is entirely possible, but talked about the refractive index of the lens and halogen filament non-point-like light source, light-type precision is difficult to simply copy.
We know that the refractive index of the impact in a ray direction of the light passing through the lens; and the distance between the lens and the reflector, but also directly affects the accuracy of the outgoing light direction. Which is easily copied, but the refractive index of the lens depends on the material itself, this is not a precision instrument analysis, it is difficult to be completely copied.
Furthermore, we are now used for the light source - halogen lamp itself is not an ideal point light source. As we all know, the filament is a certain length, may never using simple high school physics knowledge to deal with such a light source catadioptric. If high school physics knowledge can be directly utilized our own to buy a spherical glass shell, cut in half, the inner surface coated with a reflective film, the lamp is mounted in the position of the center of the sphere, can be used as spotlights with a.
Look at the different positions of the light placement at the filament emission light at that point, non-point-like light source in order to precisely control the final type of light, must rely on the professional-aided design software, software filament point-by-point optical path superimposed be able to get the final optical design (which is why many people install HID