Gas modulation refractometry is a technique for assessment of gas refractivity, density, and pressure that, by a rapid modulation of the gas, provides a means to significantly reduce the pickup of fluctuations. Although its unique feature has previously been demonstrated, no detailed explication or analysis of this ability has yet been given. This work provides a theoretical explanation, in terms of the length of the modulation cycle, of the extent to which gas modulation can reduce the pickup of fluctuations. It is indicated that a rapid modulation can significantly reduce the influence of fluctuations with Fourier frequencies lower than the inverse of the modulation cycle length, which often are those that dominate. The predictions are confirmed experimentally.

中文翻译：

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气体调制功能可减少折射计波动的吸收

气体调制折光法是一种用于评估气体折射率，密度和压力的技术，通过气体的快速调制，可以显着减少波动的吸收。尽管以前已经证明了其独特的功能，但尚未对此功能进行详细的说明或分析。这项工作就调制周期的长度而言，就气体调制可以减少波动的吸收程度提供了理论解释。已经表明，快速调制可以显着减小傅立叶频率低于调制周期长度倒数的波动的影响，而傅立叶频率通常是占主导地位的调制周期长度的倒数。这些预测在实验上得到了证实。