NIRPS Fiber Link
The optical fiber link consists of a set of four fibers, which transport the star light from the focal plane of the NIRPS front-end to the spectrograph’s input focus. On both ends, the fibers are coupled with small relay optics, which converts the slow F-number of the front-end to a faster beam (more efficient for transport in the fiber) and back to a slower beam to feed the spectrograph.
The fibers are grouped in pairs. One pair called “High resolution” and one pair called “High efficiency”. Each pair contains a science fiber and a calibration fiber. On the front-end side, each pair of fibers and their relay optics are embedded in a mechanical system (fiber head) allowing to perform alignment of the optical system of both fibers individually on 5 axes. Each head has also a pierced concave or flat mirror placed in the focal plane of the front-end. The light coming from the telescope passes through the two small holes in the mirror. Each hole is independently re- imaged on the fiber entrance surface by the relay optics such to ensure a perfect illumination of the fiber link.