Contemporary domestic radiation-resistant imaging systems predominantly utilize a reflective structure that combines ray shielding with reflective imaging to achieve radiation resistance. While light path reflection imaging prevents direct radiation damage to electronic components within the shielding shell, this approach necessitates substantial space for mirrors, resulting in systems with large size and complex structures. Furthermore, the utilization of high-density shielding materials, such as lead, substantially increases system weight, creating operational limitations and restricting application versatility. To address these challenges, this study presents a radiation-resistant imaging system based on optical fiber image transmission bundles, incorporating radiation-resistant optical glass technology and flexible fiber-optic transmission configuration. The design connects a front-end radiation-resistant objective optical system in the nuclear radiation zone with a rear-end coupling optical system and complementary metal oxide semiconductor (CMOS) image sensor in the non-radiation zone. This configuration facilitates physical isolation, effectively shielding high-energy rays and achieving superior radiation resistance. The approach resolves existing limitations of domestic radiation-resistant imaging systems regarding size, weight, radiation dose rate, and total dose, offering significant potential for nuclear energy utilization, nuclear power development, and equipment localization.

We designed a radiation-resistant objective lens using JGS1 quartz and ZF706 radiation-resistant optical glass, and prepared a quartz fiber image bundle with a pixel count of more than 500000 using the filament alignment and laminating technique. Combining those with a coupled lens, a CMOS camera, and the control and display system, a high radiation resistance optical imaging system was installed. The cobalt source was used to irradiate the radiation-resistant optical imaging system, with an irradiation dose rate of 1.0×10⁴ Gy/h. During the irradiation process, the resolution performance of the optical imaging system was tested using the ISO 12233 standard resolution test card. The resolution test was performed when the imaging system irradiates to the corresponding dose points: 0, 2.50×10⁵, 5.00×10⁵, 7.50×10⁵, 1.00×10⁶ Gy and 1.21×10⁶ Gy. To comprehensively analyze the primary factors contributing to the decreased transmittance of the radiation-resistant imaging system post-irradiation, the transmittance at various dose points of the matching objective lens was evaluated using a spectrometer. Due to the complexity of disassembling the image transmission bundle during irradiation, its transmittance was measured only before and after irradiation.

During the irradiation process, the radiation-resistant optical imaging system is tested using the ISO 12233 standard resolution test card to evaluate its imaging performance. The resolution test is conducted online at an irradiation dose rate of 1.0×10⁴ Gy/h. The resolution test is carried out at the corresponding dose points: 0, 2.50×10⁵, 5.00×10⁵, 7.50×10⁵, 1.00×10⁶ Gy and 1.21×10⁶ Gy. As shown in Fig. 11, the resolution test results indicate that the system maintained a resolution better than 25 lp/mm. No significant degradation in image resolution is observed, apart from slight browning during irradiation. The browning effect can be attributed to two main factors. 1) The target plate itself undergoes browningdue to irradiation exposure. 2) After irradiation, the transmittance at the shorter wavelengths decreases more significantly than that at the longer wavelengths, leading to severe absorption during short-wave transmission. To thoroughly analyze the primary factors affecting the decrease in transmittance of the radiation-resistant imaging system, the transmittance of its spectral lens at different dose points is investigated. Figure 12 shows the transmittance test curve of the accompanying objective lens of the high-radiation-resistant imaging system under different cumulative irradiation doses. The transmission first declines and then stabilizes during irradiation. After the irradiation dose reached 1.21×10⁶ Gy, the average transmittance (between 400 nm to 760 nm with a sampling interval of 0.58 nm) decreased by 6.26% compared to the value before irradiation. The decrease of transmittance at the longer wavelenghts is relatively minor, registering 3.34%@600 nm, compared to the pronounced decrease at the shorter wavelengths, i.e. 18.23%@450 nm. This finding further supports the browning analysis discussed earlier. Due to the irradiation test conditions, where the maximum dose rate is 1.0×10⁴ Gy/h and the test duration is relatively long, the experiment stopped when the total dose reached 1.21×10⁶ Gy. However, this threshold in fact do not reach the limit of the self-developed radiation-resistant glass ZF706. The radiation resistance limit will be further studied according to actual needs in the future. During irradiation, because the image transmission bundle is difficult to disassemble, only the transmittance before and after irradiation is tested, and the results are shown in Fig. 13. In the wavelength range of 400 nm to 550 nm, the transmittance of the image transmission bundle before and after irradiation is less than 1%. Additionally, for visible light with wavelengths greater than 550 nm, no significant attenuation in transmittance is observed.

In response to the limitations of current high-dose radiation-resistant imaging systems, including their substantial size, weight, and limited continuous operation capability, this study presents an innovative high-radiation-resistant optical imaging system utilizing optical fiber bundles. The quartz fiber image transmission bundles demonstrate excellent bending flexibility and radiation resistance characteristics. The system exhibits enhanced spatial control flexibility, while its design enables miniaturization and weight reduction, making it adaptable for radiation-resistant video surveillance across diverse applications. This radiation-resistant imaging system addresses previous challenges related to equipment size, weight, and structural complexity that typically arise from increased shielding thickness requirements. Experimental results demonstrate the superior radiation resistance performance of the high-radiation-resistant optical imaging system based on quartz fiber image transmission technology. The system maintained continuous operation for 121 h under an irradiation dose rate of 1.00×10⁴ Gy/h, achieving a cumulative total radiation resistance dose exceeding 1.21×10⁶ Gy. Post-irradiation analysis revealed only minor browning of the objective lens, with its average transmittance (400 nm?750 nm) decreasing by 6.26% compared to pre-irradiation values. The system maintained consistent resolution before and after irradiation, achieving better than 25 lp/mm.