An endoscope optical system core

The present invention relates to an optical core of an endoscope system, particularly to a core of the optical system of the endoscope visible and near-infrared light imaging parfocal, it belongs to the field of minimally invasive medical care. The method used is: an objective lens group having a positive defocus and positive curvature of field, the steering group has negative defocus and negative curvature of field, while the addition of a field lens group between the objective lens group and the steering group, the field lens group is located in the focal point of the objective lens group , the field lens group in combination with the objective lens group having a positive defocus and positive curvature of field and a negative defocus and the steering group of negative curvature of field matches. Aspect of the present invention effectively addresses the shortcomings of the objective system and the steering group alone in a wide spectral range is difficult to achieve aberration correction, the steering group structure employed in the conventional steering system HOPKINS, compared with a simpler process, better control of precision, lower cost and the like, particularly suitable for infrared fluorescence minimally invasive surgery, to solve such problems in conventional endoscopic surgery requires repeated using focusing.