The telecentric optical system (TOS) is the optical system intended for monochromatic observations of luminous objects of large extent. At present several versions of the system are known. We offer the one developed in PGI. It has essential advantage concluding in its smaller sizes and weight. TOS can be used with different types of receivers and applied in various fields of atmospheric optics. The optical scheme proposed below differs from others and has higher relative aperture and less number of elements.