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磁场穿透深度λ是超导体的一个基本参数，目前，一般测试穿透深度的实验只能给出其变化量Δλ＝λ（Ｔ）－λ（０），而不能得到λ的绝对值．并且由于测量精度的限制，用给定的理论模型拟合实验结果而得到的λ也有很大的不确定性．本文对此进行了详细的分析，并用双线圈互感法研究了超导薄膜穿透深度的精确测量，并给出了磁控溅射Ｎｂ膜的测量结果．我们的研究表明，这一方法能较为准确地给出λ的绝对值，从而避免了以往的测量及拟合所导致的不确定性．基于ＢＣＳ理论并考虑样品有限的电子平均自由程后，理论计算结果与我们的测量结果吻合较好
The penetration depth λ of the magnetic field is a basic parameter of the superconductor. At present, the general test of the penetration depth can only give the change Δλ = λ (T) -λ (0), but can not obtain the absolute value of λ. And because of the limitation of measurement accuracy, the λ obtained by fitting experimental results with a given theoretical model is also greatly uncertain. In this paper, a detailed analysis is carried out. The precise measurement of the penetration depth of the superconducting thin film is studied by the double-coil mutual induction method, and the measurement results of the magnetron sputtering Nb film are given. Our research shows that this method can give the absolute value of λ more accurately and avoid the uncertainty caused by the previous measurement and fitting. Based on the BCS theory and taking into account the limited sample mean electron free path, the theoretical calculations agree well with our measurements