Abstract:
Due to the effects of Compton scattering by high-energy γ-photons and the total dose, existing integrated CIS imaging systems have very short lifespans in strong radiation environments, severely limiting their ability to perform tasks such as γ-radiation scene monitoring and scene perception. Therefore, this paper addresses the issue of the short lifespan of CMOS image sensors in high-radiation environments by designing a radiation-resistant imaging system based on conductive optics. The goal is to enhance radiation resistance, optimize imaging performance, simplify the optical system layout, and improve system reliability, ensuring effective application in radiation scene monitoring and other safety-related tasks. Firstly, a passive light-receiving front-end was constructed using fiber-optic imaging bundles to transmit the optical representation of the scene to the imaging back-end at low irradiation dose rates. The passive light-receiving front-end objective lens consists of eight lenses. Lenses 1 and 2 expand the field of view to collect more light. Lens 3 has a negative focal length, converging and effectively reducing the field of view of the rear group. The doublet lenses placed behind the aperture primarily correct chromatic aberration and field curvature of the entire optical system. The final two lenses receive the light and focus it onto the incident face of the fiber-optic bundle, ensuring that the image height matches the size of the fiber-optic bundle’s end face. The light-receiving front-end uses radiation-resistant optical materials, while the imaging back-end is made from radiation-shielding optical materials. This dual approach of radiation-resistant at the front and radiation-shielding at the rear helps reduce both the loss of light reception performance and the degradation rate of the lifespan of electronic components. The radiation-resistant optical materials mitigate optical color shifts in radiation environments, thereby reducing light reception performance loss. Meanwhile, the back-end uses radiation-shielding glass to attenuate the intensity of γ-photons, reducing the degradation rate of electronic components, such as CIS, in radiation environments. Finally, to address the issue of CIS and other devices being susceptible to the effects of γ-photons, integrated circuits in low-dose areas were reinforced with encapsulating anti-radiation materials. The optical simulation experiment of the objective lens was conducted using Zemax OpticStudio 19.4 optical simulation software. As professional optical design software, Zemax is able to accurately simulate the behavior of optical systems and conduct precise optical performance evaluations in a virtual environment. Meanwhile, the system was irradiated in a radiation chamber with a
60Co source of 5×10
5 Ci capacity, receiving a cumulative dose of 10
4 Gy. To ensure the actual imaging quality, a test card was set up and an imaging experimental setup was constructed during the evaluation experiment of the imaging effect, and image data were recorded. The results show that the MTF value in the field of view is greater than 0.8 at a spatial frequency of 21 lp/mm and greater than 0.3 at 100 lp/mm. Additionally, after exposure to a γ-ray dose rate of 2×10
3 Gy/h and a total dose of 10
4 Gy in a real
60Co irradiation chamber, the designed system maintains normal imaging performance. The system achieves an imaging resolution of 420 lines, and the spatial resolution is of good quality. These findings validate the effectiveness of the proposed radiation-resistant imaging system based on conductive optics in enhancing the lifecycle of charge-coupled imaging systems in high-radiation environments.