An optical imaging system including refractive optics and a blocking component. The refractive optical having an entrance aperture and configured to receive optical radiation via an operational aperture, to focus the optical radiation onto a focal plane to form a telecentric image plane co-located with the focal plane, the operational aperture being co-located with the entrance aperture, having a diameter less than half a diameter of the entrance aperture, and being offset from a primary optical axis that bisects the entrance aperture by at least a radius of the entrance aperture, and a blocking component located at the entrance aperture on an opposite side of the primary optical axis from the operational aperture. The blocking component being configured to block the optical radiation from exiting the refractive optics via a region of the entrance aperture where the blocking component is located.