Photomultiplier and methods of making it

A photomultiplier comprising:

• an electron ejector configured to emit primary electrons in response to incident light onto the electron ejector;
• a detector configured to collect electrons and provide an output signal representative of the incident light;
• a substrate;
• and
• a first electrode in the substrate and between the electron ejector and the detector, the first electrode configured to emit secondary electrons in response to the primary electrons impinging on the first electrode;
• a second electrode in the substrate and between the first electrode and the detector, the second electrode configured to emit secondary electrons in response to the secondary electrons from the first electrode impinging on the second electrode;
• wherein each of the first and second electrodes comprises a flat or curved surface at an angle to a normal direction of the substrate;
• wherein each of the first and second electrodes comprises a first end and a second end, the first end being closer to the electron ejector than the second end;
• wherein the first and second electrodes are spatially arranged such that the second ends of the first and second electrodes are on a same plane perpendicular to the substrate, or such that a plane that the second end of the first electrode is on and that is perpendicular to the substrate crosses the second end of the second electrode.