High-Efficiency Micro-Structured Scintillator

X-ray microtomography (with resolution of ~1 m) is used for studying the fine structures of geological materials, crack propagation, and aging effects. Microtomography is typically performed at synchrotron beamlines by imaging structures on high-resolution scintillators, with subsequent optical magnification of micron-scale features onto charge-coupled device (CCD) cameras. The resolution of the system is determined by the resolution of the scintillator; to achieve a resolution of 1 m, a uniform scintillator of similar thickness is required, which limits the efficiency of X-ray photon detection and increases the data acquisition time, which in turn limits the productivity of the expensive synchrotron facilities. Physical Optics Corporation (POC) proposes to develop a new High-Efficiency Microstructured Scintillator (HEMUS) based on a thin layer of efficient, high-density scintillator material with a specially fabricated waveguiding structure that confines the light generated upon absorption of X-ray photons within the scintillator to narrow channels, preventing beam spreading and resulting loss in resolution. In contrast to traditional scintillator structuring approaches, which divide the material into square pixels, the proposed pattern increases the X-ray absorption efficiency, reduces the cost of fabrication, and provides a more mechanically robust final structure. The waveguides in HEMUS will allow the X-ray-generated light to be channeled toward the output surface of the scintillator without loss in image resolution, which will avoid the blurring present in conventional optical systems. Therefore, the scintillator can be made sufficiently thick (~10 m) to provide efficient X-ray absorption with little degradation in the resolution, an ideal solution for DoE microtomography imaging needs. In Phase I, POC will design a prototype HEMUS scintillator and develop its fabrication process. To demonstrate the feasibility of HEMUS, POC will obtain samples of scintillator materials from Lawrence Livermore National Lab and use them to fabricate small-scale HEMUS structures. Commercial Applications and Other Benefits: The proposed HEMUS technology is likely to have many additional commercial applications outside of microtomography, such as medical imaging and nondestructive testing. Although 1-m resolution may not be necessary in such applications, the fundamental HEMUS technology may be scaled up to provide, for example, a combination of very high detection efficiency of hard X-rays, with resolution on the order of 5-30 m. One application that could immediately benefit from such an innovation would be mammography, in which high resolution is crucial for detecting early signs of breast cancer.