基于传导光学的耐辐射成像系统研制

Radiation Resistant Imaging System Based on Conductive Optics

  • 摘要: 针对CMOS图像传感器(CIS)在强辐射环境下受高能γ光子辐照生存周期短的问题,设计了一种基于传导光学的耐辐射成像系统,从传导式光学成像和抗核加固两方面延长CIS生命周期。首先,利用光纤传像束构建无源收光前端,以将场景光学描述传输至辐照剂量率低的成像后端。其次,收光前端以耐辐射光学材料为基材,成像后端以防辐照光学材料为基材,从前耐后防两个角度分别降低成像系统收光性能损失与电子元件寿命衰减率。最后,针对CIS等器件易受γ光子影响的问题,对低剂量区集成电路进行包被式抗核加固。通过Zemax仿真软件对收光前端进行了设计和优化,结果表明其视场的光学调制传递函数(MTF)值在空间频率21 lp/mm处大于0.8,100 lp/mm处大于0.3,且所设计系统在真实60Co辐照室内进行了2×103 Gy/h剂量率、累计104 Gy剂量的γ射线照射后依然可正常成像,验证了本工作设计的基于传导光学的耐辐射成像系统对提高CIS在强辐射环境下生命周期的有效性。

     

    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 5×105 Ci capacity, receiving a cumulative dose of 104 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 2×103 Gy/h and a total dose of 104 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.

     

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