Coaxial near-infrared illumination and imaging optical system design with common aperture

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.