Liebemann laser

A Liebemann laser - or shield gun - was a weapon that fired charged particles along a laser beam. Leela found one aboard the R1C and used it to destroy a door. The Fourth Doctor then warned her not to use "strange weapons".

When the R1C crashed into the planet P7E, Herrick used a Liebemann laser to break through the rock, allowing them to head for the planet's core. (DW: Underworld)