Apparatuses for collection of upstream and downstream transmission electron microscopy (TEM) cathodoluminescence (CL) emitted from a sample exposed to an electron beam are described. A first fiber optic cable carries first CL light emitted from a first TEM sample surface, into a spectrograph. A second fiber optic cable carries second CL light emitted from a second TEM sample surface into the spectrograph. The first and second fiber optic cables are positioned such that the spectrograph produces a first light spectrum for the first fiber optic cable and a separate light spectrum for the second fiber optic cable. The described embodiments allow collection of TEM CL data in a manner that allows analyzing upstream and downstream TEM CL signals separately and simultaneously with an imaging spectrograph.