he Laser System of Very Compact Inverse Compton Scattering γ-ray Source at Tsinghua university

With the development of high-brightness electron beams and chirped pulse amplification technology, the inverse Compton scattering (ICS) X/γ-ray have the characteristics of compactness, quasi-monochromatic, continuous energy tunability, and high photon energy. The application of ultra-fast laser technology has improved the temporal resolution, brightness and spectral control capabilities of the X/γ-ray. In this paper, we present the design and implementation of the laser system for the very compact inverse Compton scattering γ-ray source (VIGAS). The laser system consists of a photo-injector driving laser system and a scattering laser system. The photo injector driving laser system produces an ultraviolet (UV) pulses with 0.58 mJ pulse energy, 7.2 ps (FWHM) pulse width, and 10 Hz repetition rate at a central wavelength of 267 nm, which illuminates a photocathode to generate a high-quality electron beam. The ICS laser system produces two alternative ultrashort laser pulses with a central wavelength of 800 nm and 400 nm, respectively, to interact with the electron beam. An intense second harmonic (SH) laser with 0.5 J pulse energy is achieved experimentally by passing a TW Ti:sapphire laser pulse through a 0.59-mm KDP crystal. We obtain a uniform SH laser focal intensity distribution through wavefront correction by a deformable mirror.