beam of light
光束
例句与用法：
A transparent body of this form, often of glass and usually with triangular ends, used for separating white light passed through it into a spectrum or for reflecting beams of light.
棱镜这种形状的透明体，多为玻璃制成，通常两端为三角形，用来分解穿过柱体的白光，使光束发生色散或用来反射光线