General Shadowrun Questions III: Ya like that, Chummer?

[Lord Torath]

Hmmmm. The 'Corporate Security Handbook' (p27) makes reference to 'two part devices', a sending unit that emits a beam of light ( 'or a laser') and a receiving unit that detects it. With the alarm being raised if an intruder disrupts the beam so the receiving unit isn't getting it.

Interesting. But the adventure One Stage Before was published in 1992, and the Corp Sec Handbook was published in 1995. Anyone recall something from an earlier source?