luminous signal

例句：

1. 1. The devicesends a luminous signal toalert the user of an emergency.
   该设备向用户发送一个发光信号以警告紧急情况。
2. 2. The new technology uses luminous signals to communicate with each other.
   新技术使用发光信号彼此通信。
3. 3. Thepolice used a luminous signal to guide the wayfor the rescue team.
   警方使用发光信号为救援队指引道路。