Quartz tube enhanced Raman fiber probe for powder detection

Raman spectroscopy has been widely used in many fields due to its advantages of multi-component simultaneous detection and molecular fingerprinting characteristics, but its low detection sensitivity severely limits the further development. In order to improve the in-situ analysis capability of powder samples by Raman spectroscopy, a high-sensitivity optical fiber Raman probe based on quartz tube enhancement is proposed. The metal-coated hollow-core fiber is used for optical signal transmission, which effectively reduces the influence of background signal on Raman spectrum. The bottom of the probe is designed with a quartz tube, which increases the sampling volume and collection efficiency, it improves the detection sensitivity of Raman spectrum. Firstly, theoretical analysis of quartz tube Raman spectroscopy can improve the detection sensitivity of powder samples. Secondly, the design and implementation of the probe are introduced in detail. Lastly, the performance of the probe is further evaluated. The results show that the Raman signal intensity (NaHCO₃) increased by a factor of 2.92 compared with the spherical lens Raman probe. In order to simulate practical application scenarios, the Raman spectral information of powder samples (Na₂SO₄ and NaHCO₃) at different depths in the container is successfully obtained by using the fiber Raman probe. The quartz tube-enhanced Raman probe designed in this paper has the advantages of small outer diameter (only 2 mm) and high sensitivity. It can detect deep powder samples and provide a new way for in-situ analysis of powder samples on site.