beam angle 是什么意思

beam angle [英]bi:m ˈæŋɡl [美]bim ˈæŋɡəl （电磁）波束宽度 [例句]The ratio of the flux emitted within the solid angle defined by the beam spread , to the bare lamp flux.由光束角限定的立体角内辐射出的光通量与裸光源光通量之比。