In the UK, what are the camera looking things on the top of traffic lights at crossings? Cameras or sensors?

There are cameras that sense the presence of vehicles so that the light can change and give them a green indication. Video detectors.



There are cameras that transmit video pictures of the intersection so that the traffic engineer can modify signal timing to accommodate unusual traffic conditions. Video monitors.



There are other types of sensors to pick up emergency vehicle requests to pre-empt normal signal operation (mostly to give them a green light).In the UK, what are the camera looking things on the top of traffic lights at crossings? Cameras or sensors?
"Emitter Gun Receiver" for Emergency Vehicles to Change the Lights