We advance an original construction of a small-sized optical rotary joint with ring-like fiber optic converters made in a single monolithic fiber optic unit. It is intended for transmission of analog and digital optical signals from rotating objects (a rate of rotation of up to several thousand rpm). We developed a mathematical model and performed computer simulation of the construction, depending on the geometry and optical properties of its elements, with allowance made for radial and end beats of the rotary joint rotor section. On the basis of our calculations, we fabricated a breadboard sample of rotary joint for five optical transmission channels and studied experimentally its characteristics.