For research on the impurity of the emission of the divertor and the change in the magnetic topology structure with resonant magnetic perturbation controlling, a new catadioptric visible endoscope system for the optical diagnostics of the divertor on the Experimental Advanced Superconducting Tokamak (EAST) has been successfully developed. The system has a theoretical transmittance greater than 80% within the operating wavelength range of 380 to 750 nm. The spatial resolution is less than 1 mm at the object plane and less than 2 mm in the full depth of field (1300 to 3000 mm).

In this paper, a special technique is demonstrated to simplify the process of realizing the field of view when the optical axis points to any direction. An algorithm of asymmetric imaging simulation is also presented in detail.