The Figure shows the optical path and the four channels of the Multi-Object Spectrograph NEXUS. Each channel is dedicated to a different wavelength range, approximately Y,  J,  H and K band. The optical path starts from the focal plane where the slits will be positioned by the robotic system. The beam passes through a Field Lens and a three-mirror an-astigmatic (TMA) collimator feeding the four channels. Beam folding is obtained through a series of dichroics and mirrors. All the curved optical surfaces of NEXUS are spherical. 

The size of the instrument is 1.5 m height, while a diameter of 3 m is needed for the rotation in this configuration.