Laser beacon
A laser beacon was a device utilized by Starfleet landing parties in the 23rd century, used for attempting to make contact with a starship in orbit when normal communications were not possible.

In 2267, a landing party from the  attempted to use a laser beacon to make contact with the ship upon beaming down to the previously unknown planet Gothos. ()

Background information 
This Feinberger was described in the final draft script of  as an "Irvingoscope", an in-joke reference to TOS Prop Master Irving A. Feinberg.

This prop was reused in other episodes, with different functions. In , Kirk uses it as a soldering device. The clear, acrylic tip of the mechanism appears to be identical to the directional medical scanner located on the underside of the diagnostic panel above the convalescent beds in sickbay.

In The Making of Star Trek and the Star Fleet Technical Manual, the device is identified as a "ray gun". According to the Manual the weapon is an offensive/defensive area weapon. The weapon has a diamond emitter tube and two buttons, one for stun and the other for disrupt. The stun setting delivers a wide stun beam with an effective range of 180 meters and an 8 meter diameter effective area at that range. The disrupt setting fires a lethal beam with the range of 90 meters and a diameter of 3 meters.

Communications technology
de:Laser (Signalgerät)