light pen

(computing 计) (also wand) photoelectric device, shaped like a pen, that can communicate with a computer either by making marks on the screen of a visual display unit or by reading the pattern of a bar code 光笔（人机通信光电装置, 呈笔形, 可用以在屏幕上作记号或读条形码）.

lifebelt (also lifebuoy), lifeboat, lifeless, lifelessly, lifelessness, lifelike, lifeline, lifelong, lifer, lifestyle, lifetime, lift, lift-attendant, lift-off, ligament, ligature, light, light bulb, light industry, light meter, light up, light-coloured, light-fingered, light-headed, light-hearted, light-heartedly, light-heartedness, light-heavyweight, light-sensitive, light-year, lighten, lighter, lighterage, lighterman, lighthearted, lighthouse, lighting, lightly, lightness, lightning,