Light output enhancement of scintillators by using mixed-scale microstructures.

Scintillators play an important role in the field of nuclear radiation detection. However, the light output of the scintillators is often limited by total internal reflection due to the high refractive indices of the scintillators. Furthermore, the light emission from scintillators typically has an approximately Lambertian profile, which is detrimental to the collection of the light. In this paper, we demonstrate a promising method to achieve enhancement of the light output from scintillators through use of mixed-scale microstructures that are composed of a photonic crystal slab and a microlens array. Simulations and experimental results both show significant improvements in the scintillator light output. The X-ray imaging characteristics of scintillators are improved by the application of the mixed-scale microstructures. The results presented here suggest that the application of the proposed mixed-scale microstructures to scintillators will be beneficial in the nuclear radiation detection field.

Directional Control and Enhancement of Light Output of Scintillators by Using Microlens Arrays.

Scintillators play an important role in the field of nuclear radiation detection, such as nuclear medical imaging, dark matter detection, nuclear physics experiments, and national security. However, the light extraction efficiency of a scintillator with a high refractive index is severely restricted because of the total internal reflection. In this paper, microlens arrays have been applied onto the surface of a cerium-doped lutetium-yttrium oxyorthosilicate scintillator to improve the light extraction efficiency and to control the directivity of the light output. Compared to that of a reference sample, a 3.26-fold enhancement with an emission angle of 45° has been obtained by using microlens arrays with optimal parameters. It was also found that the enhancement ratio can be affected by the refractive index of the microlens, the spacing of individual microlens. The control mechanism of microlens arrays is revealed by a combination of simulations and experiments. X-ray imaging characteristics exhibit an improved gray scale amplitude without any loss of the spatial resolution. The present results suggest that the application of microlens arrays to scintillators is beneficial to the field of nuclear radiation detection.