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拉曼光谱检测中常用的CCD对温度较为敏感,降温可以有效降低其暗电流噪声。基于此,设计了一套制冷系统,采用有限元分析软件ANSYS分别模拟散热模块的导热情况及真空室内低、中真空度下气体流动热交换情况;实验测量了低、中真空度范围内不同真空度下温度随制冷时间变化的特性曲线,以及真空室内充入氩气、氖气、氮气作为保护气体时温度随制冷时间变化的特性曲线。结果表明氮气效果较好,并非真空度越高制冷效果越好,这与热模拟结果相符。测量了CCD在不同温度下的暗电流噪声,结果显示CCD温度对暗电流噪声影响较大,制冷可以有效减小暗电流噪声,且暗电流噪声变化与温度变化呈类指数关系。
CCD commonly used in Raman spectrum detection is sensitive to temperature, and cooling can effectively reduce its dark current noise. Based on this, a set of refrigeration system was designed. The finite element analysis software ANSYS was used to simulate the thermal conduction of the heat dissipation module and the heat exchange of gas under low and medium vacuum in the vacuum chamber respectively. Degree of temperature changes with the cooling time curve, and the vacuum chamber filled with argon, neon, nitrogen as a protective gas temperature changes with the cooling time curve. The results show that the effect of nitrogen is better, not the higher the degree of vacuum the better the cooling effect, which is consistent with the results of thermal simulation. The dark current noise of CCD at different temperatures was measured. The results show that CCD temperature has a significant influence on dark current noise, and cooling can effectively reduce the dark current noise, and the dark current noise changes exponentially with temperature.