Laser Confocal Raman Spectroscopy Imaging Technology and System with Anti-Drift Function
LI Shu-cheng1, WANG Yun1*, CUI Han1, QIU Li-rong1, ZHAO Wei-qian1, ZHU Ke2
1. Beijing Key Lab for Precision Optoelectronic Measurement Instrument and Technology, School of Optoelectronics, Beijing Institute of Technology, Beijing 100081, China
2. Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
Abstract：Confocal Raman technique, which combines confocal microscopy and Raman spectroscopy techniques, plays an important role in the field of physical science, material science, biomedical and cultural relics identification, criminal investigation with high resolution, high sensitivity, and the advantages of tomography. The existing commercial confocal Raman spectrometers have no fixed focus ability so that the sample table drift caused by defocus often appears in the measurement, which affects the measurement results. In view of this problem, a laser confocal Raman spectroscopy detection system with anti-drift capability was developed in this paper. Based on the confocal Raman detection principle, this system could realize auto focus by using Raman axial response curve of the maximum confocal position of the corresponding samples. The spectral intensity extremum position was obtained by curve fitting, and it realized the real-time location of measured samples at the confocal position to improve the effect of Raman spectral imaging. In this paper, we used the single layer graphene samples for single point test and the auto focus could be realized in 5 μm, and the intensity we got has almost no changes. We can say the system has a better ability of anti-drift. We got Raman imaging of silicon step samples. We could find that it had stable single and better lateral resolution, which was obviously superior to the conventional confocal Raman spectrum detection system in long time measurement.
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