Development of a three dimensional four mirror optical cavity for laser-Compton scattering

This paper describes a design and performance of a three-dimensional 4-mirror optical cavity for development of intense photon sources by laser-Compton scattering. We achieved the finesse of 4000 and average power of 2.6 kW in the cavity with the vertical laser beam spot size of 13±1μm in σ at the laser-electron interaction point. As a result, we observed 124±1 photons with average energy of 24 MeV per beam crossing, which corresponds to the generation of 2.7×108 photons per second.