Takehiro Kurono

Photon-Counting Imaging and its Application

Publisher Summary Photon-counting imaging systems incorporate three important features: the ability to detect individual photons or particles, spatial resolution, and the capability of real-time imaging and subsequent image analysis. Various types of photon-counting systems have been reported and applied in fields such as astronomy, high-energy physics, and spectroscopy. The chapter describes the design, operation, and performance of a photon-counting image acquisition system (PIAS) and discusses the results of basic experiments and application of a PIAS. A PIAS is developed to detect and display individual photons or particles in real time and to carry out subsequent image processing or analysis; it consists of a photon-counting imager, a position analyzer, and an image processor. The imager incorporates a photocathode, a three-stage microchannel plate (MCP), and a position-sensitive device (PSD). Various types of imagers have also been developed to detect X-ray, extreme ultraviolet (XUV), vacuum UV (VUV), UV, and visible photons, as well as charged particles. A PIAS allows real-time imaging and subsequent analysis of a very faint object whose intensity is only few counts per second for the entire image.

Performance Analysis Of The Photon-Counting Image Acquisition System

We have developed a photon-counting image acquisition system (PIAS), which can detect a two-dimensional object in a very low-light-level condition. The improvement of the system performance has been accomplished in an image distortion and gain drift owing to the improvement of the silicon PSD (position sensitive detector). The geometric shape of the electrode on the PSD has been redesigned, resulting in the small image distortion of less than 3%. The gain degradation of the electron-bombarded silicon PSD had been a biggest problem in the stable operation of the system. It has been successfully overcome by irradiating the electrons from back side of the PSD instead of front side as formerly. The spatial resolution of the system has been measured to be better than 16 1p/mm typically at the center. Its maximum data is 18 1p/mm or better. Experiments and a theoretical analysis has also been carried out to clarify the limiting parts of the spatial resolution. We have exprimented on system applications in astronomy, spectroscopes and microscopes. In astronomical observation, several kind of stars and galaxies were observed. And also using PIAS combined with the spectroscopy, we measured three spectrums nearby 365nm of Hg-lamp. Further in microscope application, we observed the fibroblast cell of rat by fluorescent microscope using PIAS.