text: During his work at the sharashka , where he was put in charge of other workers , Theremin created the Buran eavesdropping system . A precursor to the modern laser microphone , it worked by using a low power infrared beam from a distance to detect the sound vibrations in the glass windows .
simplified: Theremin created the `` Buran '' eavesdropping system which recorded conversations in French and American embassies by measuring the window glass vibrations using a low power infrared beam from a distance .