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为了解决激光瑞利散射技术诊断燃烧场时存在的米散射和背景杂散光干扰问题,发展了基于碘分子超精细吸收凹陷的滤波技术。介绍了分子滤波的原理和碘分子的吸收光谱,设计了用于产生稳定数密度的碘分子滤波器,并采用种子注入、可调谐Nd:YAG激光器测量了碘分子的吸收谱。采用碘分子滤波器,在稳态燃烧场和瞬态燃烧场上分别进行了结构诊断的滤波瑞利散射实验,获得了清晰的燃烧场结构图像。实验表明碘分子滤波器能够有效抑制532nm激光瑞利散射实验中的米散射和背景杂散光,提高信号图像的清晰度。
In order to solve the problems of the rice scattering and the background stray light interference when the laser Rayleigh scattering technique is used to diagnose the combustion field, a filtering technique based on the hyperfine absorption depression of iodine molecules has been developed. The principle of molecular filtering and the absorption spectrum of iodine molecule are introduced. The iodine molecular filter used to generate stable number density is designed. The absorption spectrum of iodine molecule is measured by using tunable Nd: YAG laser with seed implantation. Using iodine molecular filter, the structured Rayleigh scattering experiment of structural diagnosis was carried out on steady state combustion field and transient combustion field, respectively, and a clear image of combustion field structure was obtained. Experiments show that the iodine molecular filter can effectively suppress the scattering of rice and background stray light in the 532 nm laser Rayleigh scattering experiment and improve the definition of the signal image.