  The coincident detection of particles is a powerful method in experimental
physics, enabling the investigation of a variety of projectile-target
interactions. The vast majority of coincidence experiments is performed with
charged particles, as they can be guided by electric or magnetic fields to
yield large detection probabilities. When a neutral species or a photon is one
of the particles recorded in coincidence, its detection probability typically
suffers from small solid angles. Here, we present two optical assemblies
considerably enhancing the solid angle for EUV to VIS photon detection. The
efficiency and versatility of these assemblies is demonstrated for
electron-photon coincidence detection, where electrons and photons emerge from
fundamental processes after photoexcitation of gaseous samples by synchrotron
radiation.
