Cioeta, F. Chiadroni, E. Cianchi, A. Di Pirro, G. Franzini, G. Marongiu, M. Mostacci, A. Palumbo, L. Shpakov, V. Stella, A. Variola, A. JACoW Geneva, Switzerland 978-3-95450-177-9 10.18429/JACoW-IBIC2016-TUPG74 English 533-536 TUPG74 target linac diagnostics optics radiation Contribution to a conference proceedings 2017 2017-02 http://dx.doi.org/10.18429/JACoW-IBIC2016-TUPG74 http://jacow.org/ibic2016/papers/tupg74.pdf A high brightness electron Linac is being built in the Compton Gamma Source at the ELI Nuclear Physics facility in Romania. To achieve the design luminosity, a train of 32, 16 ns spaced, bunches with a nominal charge of 250 pC will collide with the laser beam in the interaction point. Electron beam spot size is measured with an OTR (optical transition radiation) profile monitors. In order to measure the beam properties, the optical radiation detecting system must have the necessary accuracy and resolution. This paper deals with the studies of different optic configurations to achieve the magnification, resolution and accuracy desired considering design and technological constraints; we will compare several configurations of the optical detection line to justify the one chosen for the implementation in the Linac.