Improvement of Light Collection Efficiency of Lens-Coupled YAG Screen TV System for a High-Voltage Electron Microscope

0205234 - UPT-D 20000010 RIV US eng J - Journal Article
Yamamoto, K. - Tanji, T. - Hibino, M. - Schauer, Petr - Autrata, Rudolf
Improvement of Light Collection Efficiency of Lens-Coupled YAG Screen TV System for a High-Voltage Electron Microscope.
Microscopy Research and Technique. Roč. 49, č. 6 (2000), s. 596-604. ISSN 1059-910X. E-ISSN 1097-0029
Institutional research plan: CEZ:AV0Z2065902
Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering
Impact factor: 1.746, year: 2000

A new lens coupling television (TV) system using a YAG (Yttrium Aluminium Garnet: Y₃Al₅O₁₂:Ce³⁺) single crystal screen developed for a high-voltage electron microscope (HVEM), and its performance is examined. The system, using a combination of YAG and lenses, is less damaged by high-energy electron irradiation and reduces the influence of X-rays in the image. YAG screens have not been used for lens-coupling systems, because the high refractive index (n=1.84) of YAG results in a low light collection efficiency for emited light. This disadvantage is overcome by combining a thin YAG disk screen (thickness, 100 .mu.m) with a glass hemisphere whose refractive index is 1.81. We found that the ligt intensity is almost the same as that obtained with conventional P22 powder screen and lenses system. The resolution is about 55 .mu.m on the YAG screen, and this value is 1.3 times higher than that measured by the conventional system. Shading and distortion do not affect TV observation. Detection quantum efficiency obtained after correction of the channel mixing effect, is about 0.1.
Permanent Link: http://hdl.handle.net/11104/0100852