In the mirror universe, the transpectral sensor array was an advanced type of sensor array which Professor Jennifer Sisko was developing for the Klingon-Cardassian Alliance in the early 2370s. The purpose of the array was to detect the Terran Rebellion bases in the Badlands and enable the Cardassians and the Klingons to launch an assault.
In 2371, Miles O'Brien kidnapped Benjamin Sisko from Deep Space 9 and brought him to the mirror universe. O'Brien hoped Sisko would be able to convince Jennifer to stop work on the array and join the Terrans. Sisko was successful and Jennifer stopped work on the array and left Terok Nor. (DS9 episode: "Through the Looking Glass")