Fiber Probe Based On Spatially Offset Raman

Spatially Offset Raman Spectroscopy(SORS)technology is a new type of spectrometer technology that solves the bottleneck of conventional Raman detection technology due to the fluorescence interference of the surface layer of the object,which can provide more accurate test results.Unlike the conventional Raman detection technology,its laser shooting point does not coincide with Raman’s collection point,but there is a certain space offset distance △s.Such a structural design enables SORS technology to effectively inhibit the surface fluorescence of the object,and at the same time,it can test the Raman signal from different deep layers inside the surface.The conventional SORS test method uses free spatial optical design,thus the tests require precise debugging.It is only suitable for laboratory and with high cost.This thesis theory analyzes the principle of SORS detection and set up a free spatial optical SORS spectrum detection system to prove that it can effectively analyze compositions of the contents of Bagan wooden by penetrating their skin.Because the structure of free space optical SORS is complex,it can only be applied in the laboratory.Therefore,this thesis focused on the study of the optical fiber SORS probes,and compares them with the free spatial optical SORS detection system.The specific work is as follows:We firstly investigated the structure of the portable Raman spectrum detectors and their probes,explain the frameworks composition of the portable Raman system and the theoretical basis,collection mode,surface thickness and best space offset distance of Raman detection.The spatial offsets of the different structures studied here in this thesis laid the foundation.Secondly,as the starting point of the work of this project and the reference of subsequent research,the collection principles of the Raman spectral signals were designed and set up a free space optical SORS spectrum detection system.Our experiments have proved that for the free space optical SORS,the signal collected at 45 degrees on the other side has better suppression effects of fluorescence than that collected in the direction of vertical objects.Then,the dual fiber SORS detection probe was designed,and the probe was used to test the ethanol in the brown glass bottle and antibiotics in the capsule.Experiments found that the intensity of Raman’s characteristic peak signals from deep layers of the samples changed with the changed offset in free space,which preliminarily illustrated the correctness of the fiber SORS detection probe.Finally,the multi-fiber SORS detection probe was studied.Compared with the dual fiber SORS spectrum detection system,it increased the number of optical fiber which collected Raman signals,obtained a stronger Raman signal efficiency.The spatial offset distance required for the strongest Raman signal is different for different thickness of the skin layers of the objects.In general,this thesis conducted in-depth exploration and research on the design and application of SORS probes,revealing that the optical fiber SORS probe can break the application limit of conventional Raman spectral probe technology.The analysis of the compositions of deep layer substances in situ provides a reference for the field application of the SORS system.