Photopolymer-based volume phase holographic grating for astronomical instrumentations

Green sensitive photopolymers have been studied to produce volume phase gratings (VPHGs) to be used as dispersing elements in astronomical instrumentations. They have been characterized determining the parameters that affect the diffraction efficiency (thickness, refractive index modulation, exposure, line density, etc.). Different prototypes have been produced varying all the selected parameters. The optical proprieties of the devices were investigated to understand the quality of the gratings. The results were encouraging, therefore, to experience the possibility to produce a VPHG for astronomical applications, low dispersion prototype has been designed, and it will be mounted in the AFOSC camera (Asiago, Italy).