| 摘要 |
PURPOSE:To make it possible to perform spectrum measurement with high resolution, by forming BPFs in a window, arranging an optical fiber, thereby preventing the inclusion of high-order light, stray light and unnecessary light. CONSTITUTION:A transparent optical fiber 3 having a desired wavelength region is arranged in the vicinity of or in close contact with a window 6 and a light receiving surface 2 of a light receiving element. In the window 6, a stray removing filter 4 and a high-order-light removing filter 5, which have desired transmitting characteristics in correspondence with the desired wavelength region of the light receiving element, are constituted. As a result, the effect of the high-order light, the stray light, which is imparted by the sensitivity difference due to the wavelengths of the photodiode, and the unnecessary light due to the repeating reflections between the light receiving surface 2 and the window 6 can be removed. |
