full beam
noun [ U ] UK uk/ˌfʊlˈbiːm/ us/ˌfʊlˈbiːm/ (US brights [ plural ])
（汽车的）远光灯，大灯
If a car's headlights are on full beam, they are as bright as they can be, and directed straight ahead.
If your lights are on full beam, you may dazzle oncoming drivers. 如果你开远光灯，你会让对面来车的司目眩。