Contribution Oral presentation
Lens manufacturing for the near future missions of ultra high energy cosmic rays
We present the lens manufacturing for the near future missions of ultra high energy cosmic rays. The EUSO ultra long duration balloon flight mission and the K-EUSO project have been planed. The balloon optics is compose of two Fresnel lenses and a diffractive lens. The K-EUSO optics is composed of a primary aspherical mirror and a Fresnel lens as a corrector lens. RIKEN will provide Fresnel lenses for both projects.