The invention relates to a pockels cell comprising two spaced-apart cubical RTP crystals that have a square cross section, are located one behind another, and are oriented towards each other so as to provide thermal compensation in the direction of radiation. Each of said RTP crystals is provided with electrodes on two opposite faces, said faces of one crystal being rotated by 90.degree. relative to the faces of the other crystal and relative to the direction of radiation (5). Flexible, electrically insulating, high voltage-proof plastic mats which conduct heat well and rest against the inside of a cooling member are provided around the exterior faces of the electrodes.
