BIGRE: a new double microlens array for the integral fieldspectrograph of SPHERE

摘要

IFS is the Integral Field Spectrograph for SPHERE, a 2nd generation instrument for VLT devoted to the search of exoplanets.To achieve the performances required for the IFS a new device sampling the focal plane has been designed, prototyped and tested in laboratory. This device named BIGRE consists of a system made of two microlens arrays with different focal lengths and thickness equal to the sum of them and precisely aligned each other. Moreover a mask has been deposited on the first array to produce a field stop for cach lenslet. Laboratory tests confirmed that specifications and properties of the prototype are met by state of the art on optics microlens manufacturing.To characterize the device, a simulator of IFS has been built in laboratory and the BIGRE properties have been tested in real working conditions, showing that the design of the double array fulfills IFS requirements.