An infrared liquid nitrogen (LN2) cooled focal reducer camera has been designed to be used at the 1.5 m (f/13.8) Carlos Sanchez IR Telescope (CST) at the Observatorio del Teide. The image quality is better than 30 micrometers (typical pixel size of the detector) with an image scale of 0.5 arcsec/pixel. The final design is a very compact system which consists of a centered reflective system with a CaF(subscript 2) lens which will be used as window of the dewar. The system is free of chromatic aberration, reduces the amount of coma presents in the telescope and allows us to get a homogeneous image quality over the detector. Vignetting effects on the transmission are studied and found below the 20%. The use of aluminum diamond turned optics lets us obtain the tight tolerances needed to get the maximum optical performance with a system which is practically insensitive to temperature changes. Spot diagrams at different wavelength from 1 to 5 micrometers using a real simulation of the complete system (CST + camera) are presented. The baffling of the system is also analyzed.14