The synchrotron radiation emitted in the infrared range from a bending magnet of the Storage Ring of ALBA was extracted from a modified dipole chamber, allowing acceptance-opening angle of 43(H) x 25.17(V) mrad². The infrared beam is extracted in the horizontal plane using a laterally inserted flat mirror. MIRAS exploits the infrared synchrotron emission from the two main sources of radiation, edge and constant field emissions of the bending magnet. The optical layout of MIRAS includes the option for splitting the extracted infrared beam in two sectors, with one containing the edge radiation of the beam. This configuration will enable, in a future upgrade, the use of the two beams simultaneously at different endstations. The experimental cabin and transport optics are designed for such a future upgrade of the MIRAS beamline.

Following the previously mentioned extraction geometry "horizontal then vertically upward deviation of the beam", a toroidal mirror M3 focusing the beam horizontally through the tunnel wall. After the first focus, the beam is made collimated using two cylindrical mirrors.