Impact of high ionizing dose on high-power white LEDs

National audienceVisible cameras operating at 1 MGy of g radiation require radiation tolerant illumination system. Here, commercially available high-power white LEDs have been tested under X and g radiations. The light power of white commercial LED was shown to slightly decrease (less than 10 %) in post irradiation measurements. A closer analysis, based on the ABC model for efficiency droop, reveals that irradiation essentially increases the amount of trap assisted recombination, impacting the LED quantum efficiency mostly at low supply voltage. This suggests that favoring the LED operation at higher supply voltage could be a good strategy to enhance the radiation hardness of LED-based illumination systems

In-Situ Optical Characterization of Bulk Optical Glasses Under Protons and X-rays

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Investigations of the MGy dose level radiation effects on the photometric budget of a radiation-hardened CMOS-based camera

International audienceWe studied the impact of ionizing radiation at high dose levels (megagray, MGy) on the photometric budget of a radiation-resistant complementary metal oxide semi-conductor (CMOS)-based camera. This is achieved by measuring the radiation-induced degradation of each subpart, namely its illumination system, its optical system, and its CMOS image sensor. The acquired experimental results allow performing a rather realistic simulation of the radiation effects at the system level. Thanks to appropriate mitigation techniques, limited image darkening and color change are obtained at MGy dose levels. The presented results confirm the feasibility of a CMOS-based camera able to resist to MGy dose level of ionizing radiations with an acceptable degradation of the image quality, opening the way to its implementation in the most challenging harsh environments

Impact of high ionizing dose on high-power white LEDs

National audienceVisible cameras operating at 1 MGy of g radiation require radiation tolerant illumination system. Here, commercially available high-power white LEDs have been tested under X and g radiations. The light power of white commercial LED was shown to slightly decrease (less than 10 %) in post irradiation measurements. A closer analysis, based on the ABC model for efficiency droop, reveals that irradiation essentially increases the amount of trap assisted recombination, impacting the LED quantum efficiency mostly at low supply voltage. This suggests that favoring the LED operation at higher supply voltage could be a good strategy to enhance the radiation hardness of LED-based illumination systems

Impact of high ionizing dose on high-power white LEDs

National audienceVisible cameras operating at 1 MGy of g radiation require radiation tolerant illumination system. Here, commercially available high-power white LEDs have been tested under X and g radiations. The light power of white commercial LED was shown to slightly decrease (less than 10 %) in post irradiation measurements. A closer analysis, based on the ABC model for efficiency droop, reveals that irradiation essentially increases the amount of trap assisted recombination, impacting the LED quantum efficiency mostly at low supply voltage. This suggests that favoring the LED operation at higher supply voltage could be a good strategy to enhance the radiation hardness of LED-based illumination systems

Radiation vulnerability of standard and radiation-hardened optical glasses at MGy dose: Towards the design of tolerant optical systems

International audienceFacing the need of cameras able to withstand high levels (MGy) of ionizing radiation and the limited set of radiation-hardened optical glasses available to manufacture the lenses of their optical systems (OS), we performed an evaluation of standard and radiation hardened glasses. One of our objectives was to understand if selecting only radiation hardened glasses is always the best choice to reduce OS radio-darkening that is the main radiation-induced macroscopic degradation. For this, we performed X-ray in situ measurements of the radiation-induced attenuation (RIA) up to 100 kGy(SiO2) for several Ce-doped glasses from SCHOTT. Their responses are compared to their Ce-free counterparts. Due to the strong intrinsic attenuation of radiation hardened glasses caused by the Ce-codoping at shorter wavelengths, we found nearly no advantage to use radiation-hardened glasses at doses below 1 kGy(SiO2). We also performed post-irradiation RIA measurements on 31 standard glasses irradiated up to 1 MGy (γ-rays). The outcome is that several standard glasses especially the ones with a low Abbe number and a high refractive index are sufficiently radiation tolerant in terms of RIA and can serve as promising alternative to rad-hard ones. The use of these glasses less affect the color rendering of OS and strongly reduce their costs