This paper introduces a new method to measure the intensity distribution of single seam diffraction by replacing the silicon photocell and light activated diode with light activated triode. A Low Noise and High Sensitive Photo Diode Detector Used in Tokamak Visible Light Measurement 利用光敏三极管代替硅光电池和光敏二极管来测试单缝和双缝衍射的光强分布。测量托卡马克可见光谱辐射的低噪声、高响应光敏二极管探测器