A laser-Compton backscattering beam, which we call a `Laser-Electron Photon beam, was upgraded at the LEPS beamline of SPring-8. We accomplished the gains in backscattered photon beam intensities by factors of 1.5--1.8 with the injection of two adjac
ent laser beams or a higher power laser beam into the storage ring. The maximum energy of the photon beam was also extended from 2.4 GeV to 2.9 GeV with deep-ultraviolet lasers. The upgraded beams have been utilized for hadron photoproduction experiments at the LEPS beamline. Based on the developed methods, we plan the simultaneous injection of four high power laser beams at the LEPS2 beamline, which has been newly constructed at SPring-8. As a simulation result, we expect an order of magnitude higher intensities close to 10$^7$ sec$^{-1}$ and 10$^6$ sec$^{-1}$ for tagged photons up to 2.4 GeV and 2.9 GeV, respectively.
The first photon beam was successfully produced by laser Compton backscattering at the LEPS2 beamline, which was newly constructed at SPring-8 for the purpose to increase the beam intensity one order of magnitude more than that of the LEPS experiment
s and to achieve the large acceptance coverage with high resolution detectors. The BGOegg electromagnetic calorimeter with associated detectors are being set up at the LEPS2 experimental building for the physics programs, including the searches for $eta$-bound nuclei and highly excited baryon resonances. In parallel to the BGOegg experiments, the LEPS2 charged particle spectrometer will be prepared inside the 1 Tesla solenoidal magnet, transported from the BNL-E949 experiment.
Production of a GeV photon beam by laser backward-Compton scattering has been playing an important role as a tool for nuclear and particle physics experiments. Its production techniques are now established at electron storage rings, which are increas
ing worldwide. A typical photon intensity has reached $sim$ 10 $^6$ sec$^{-1}$. In the present article, the LEPS beamline facility at SPring-8 is mainly described with an overview of experimental applications, for the purpose to summarize the GeV photon beam production. Finally, possible future upgrades are discussed with new developments of laser injection.
