Enlarged linearity range of a Rasnik system using an integrating sphere

Rasniks elements are foreseen to be used in the CMS alignment system. The large displacements and deformations expected for the different subdetectors demands large linearity response range of the alignment components. By the use of an integrating sphere coupled to the light source, we have optimized the homogenity of the beam, leading to improvement, by factor three, in the linearity range of the Rasnik system with respect to conventional configurations, preserving the measurement position resolution. The range obtained coincides with the maximum reachable with the geometry of the used components.