Where do laser range finders emit and receive the beam?

[Jones1987]

For these LFR's

http://www.active-robots.com/products/sensors/hokuyo.shtml

Where exactly is the laser being shot from and recieved? The circular top? or is there something we cannot see under neath/behind?

Thanks

 

[Dr Lots-o'watts]

It looks like a little lighthouse. I understand the beam comes out laterally from the tower, through a black window along the circumference.