light pen
noun
1
- Computing a hand-held pen-like photosensitive device held to the display screen of a computer terminal for passing information to the computer【计算机】光笔（手持式光敏装置, 外观如笔, 使用时将其接触计算机终端显示屏以便传输信息）。
2
- a hand-held light-emitting device used for reading bar codes（手持式发光）条形码解读器。