The BOSS project allowed the first precise measurement to the percent of the BAO peak at z <0.7 on the ground. The eBOSS project will extend the redshift range. But to gain additional precision factors, current ground-based instrumentation is no longer sufficient and new spectrographs are needed. The DESI project (Aghamousa et al., 2016) consists of an innovative multi-object spectrograph (10 spectrographs with 3 spectral channels each), powered by 5000 optical fibers, which can thus produce 5000 spectra of galaxies in parallel. The instruments will be installed on the 4-meter-diameter Mayall telescope in Arizona, USA, which was dedicated to this project. This instrument will allow a systematic survey of 14,000 square degrees observed for 500 nights, for a total of 20 million objects, in particular the emitter galaxies of the spectral shift [OII] between 0.5 With the LAM and the OHP in 2014, we obtained funding from AMIDEX (IDEX from Aix-Marseille Université) in support of the DESI project as part of a call for technology transfer. With this support we are participating in the construction of a prototype spectrograph to be delivered in 2017. This prototype is built and assembled at WINLIGHT, based in Pertuis (84), in collaboration with LAM and L'OHP (Observatoire de Haute Provence ). WINLIGHT manufactures optical elements and laboratories (mainly OHP) are responsible for the integration, testing and verification of the performance of the spectrograph. Our group thus financed appears in DESI as a regional pole (AMU-RPG). We therefore monitor this activity, in particular we provide expertise on detectors during integration tests and on performance. The schedule foresees that the second spectrograph be tested in the autumn of 2017 and then the frequency is 1 spectrograph every 6 weeks for a final delivery of the 10 spectrographs towards mid-2019.Technical activities