The present invention includes a transmissive-reflective photocathode including a membrane configured to absorb photons from an illumination source via a first surface of the membrane, the membrane further configured to emit photoelectrons in a reflection mode via the first surface, the membrane further configured to emit photoelectrons in a transmissive mode via a second surface, the first surface and the second surface being substantially parallel, and a membrane support structure configured to mechanically secure the membrane, the membrane support structure further configured to provide at least a first pathway between the first surface and free space and a second pathway between the second surface and free space.