Traditional optical imaging system cannot achieve full field of view and high magnification simultaneously. Enslaved to resolution of detector array, the imaging field vision and magnification cannot be satisfied at the same time. Zoom lens can only vary the magnification for the center field of view, and it is not able to show the large observation field of view and local optical magnified image of either area at one glance. When the focal length of zoom lens reaches the long end, the field of vision will reduce, which leads to missing of marginal targets. The shortage of traditional imaging technique will entail inconvenience. In this paper, we propose a new scheme of geometrical optics imaging system combining two imaging optical path of different focal length in one optical system and the two optical paths image on the same detector array simultaneously. The local optical path can image for arbitrary position of targets and its focal length is variable using liquid lens. The final local variable magnification imaging optical system is shown as example. We offer the detailed design and simulation results, which shows that this kind of optical path configure can image for large field of view and arbitrary local detail at the same sight and maintain acceptable imaging performance.
Imaging optical system with coaxial common aperture near-infrared illumination containing both imaging optical path and illumination light path is established. The imaging optical path is coaxial and shares the front objective lens with the illumination light path. An aspherical short-focus single lens is adopted to decrease the blink surfaces in numbers and simplifies the optical structure. The ghost imaging path is traced backwards to locate the stray light. Absorption region set in the reflector plate eliminates the ghost images induced by the illumination rays reflected by front objective lens surfaces. A uniform rod is adopted to mix the light of near-infrared source, and the reflector plate locates in the conjugate position of aperture stop of both imaging optical path and the illumination light path, which can reduce the impact of occlusion of the reflector plate and ensure the illumination uniformity of the target object. The optical system covers the full field of view of 54° and imaging spectrum range of 450nm to 860nm. We offer the detailed design and simulation results. It shows that this optical system can make good imaging performances and illumination uniformity, and maintain compact structure.