Optical data receiver

481THz weak signal receiver. Used to detect a very weak optical signal by clear air scatter over an 8.5km non line-of-sight path.

[Padlock]

Whoa looks like an expesnive gadget.

[xbm]

No, actually it cost very little. The optics consist of a £1 magnifying glass (handle removed) in a piece of 110mm drain pipe with some low cost electronics.