| 摘要 |
PURPOSE:To achieve high sensitivity and high resolution with ease of handling and at a low cost by providing a thin-film shaped filter at an incidence side and by absorbing or reflecting a visible light. CONSTITUTION:A thin-film shaped filter 2 for transmitting soft X rays and reflecting or absorbing visible light is placed at an incidence side of an inexpensive detector 1 with sensitivity for both soft X rays and visible light. Since the transmission of soft X rays of this filter 2 is N-times or more larger than that of visible light, a thickness d should satisfy d>=lnN/{4pi(KV/lambdaV-KX/lambdaX)}, where KV and KX indicate the absorption coefficient of visible light (wavelength:lambdaV) of a material of the filter 2 and that of the soft X rays (wavelength:lambdaX). For example, when N is equal to 100, the thickness d is equal to or larger than 0.366/(KV/lambdaV-KX/lambdaX), thus achieving high sensitivity for the soft X rays, eliminating sensitivity for ultraviolet rays or light in visible light region, and obtaining a high resolution.
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