塑料物证在案件分析中起着重要的作用，如何高效准确地辨别塑料的种类和来源是物证分析领域备受关注的技术。提出了利用塑料对应的“指纹”X射线能谱对塑料进行无损溯源分析的方法。为了得到塑料对应的“指纹”X射线能谱，研制了平行束毛细管X光透镜（PCXRL），设计了基于PCXRL和实验室普通X射线光源的X射线荧光谱仪，该谱仪的最小探测极限在1~35 ng/cm2的范围内，在17.4 keV时，PCXRL整个束斑的直径为3066 μm，整个束斑的放大倍数为12.7，在束斑中心有个强度均匀分布的“坪区”，该“坪区”的直径为570 μm，该处的放大倍数为47.5，这便于高效准确地对各种尺寸的塑料进行溯源分析。实验证明PCXRL在塑料物证鉴别技术中有着潜在的应用价值。

The identification technology of plastic evidence is very important in forensic sciences. The X-ray energy spectra as a fingerprint of the plastic evidence is proposed to identify non-destructively the plastic evidence. The parallel capillary X-ray lens (PCXRL) is designed, and the X-ray fluorescence spectrometer based on the PCXRL and the laboratory X-ray source is developed to obtain the X-ray energy spectra as the fingerprint of the plastic evidence. The minimum detection limit of this X-ray fluorescence spectrometer is in the range of 1~35 ng/cm2. The diameter and the gain of full beam focused by the PCXRL are 3066 μm and 12.7 at 17.4 keV, respectively. There is a plateau where the distribution of the X-rays is uniform in the center of the focused beam. The diameter and the gain of this plateau is 570 μm and 47.5 at 17.4 keV, respectively. These are helpful to identify efficiently the plastic evidence with various sizes. The PCXRL has potential application in the identification technology for plastic evidence.