Design And Implementation Of Optical System For Handheld Raman Spectrometer

Raman spectroscopy is the scattering spectrum of matter.The frequency shift,intensity and distribution of the spectrum line are directly related to the energy level of the molecule,which can provide the characteristic information of material structure.Compared with the traditional detection technology,Raman spectroscopy has the advantages of fast detection speed,non-contact,and no sample preparation.It has been widely used in university scientific research,security,food safety,pharmaceutical identification and other fields.Raman spectroscopy is also one of the fastest growing frontiers in spectroscopy research.The traditional Raman spectrometer is generally large and expensive,which is only suitable for laboratories of scientific research institutes or institutions of higher learning.As a portable implementation of Raman detection technology,hand-held / portable Raman spectrometer is very suitable for on-site detection of substances,and its operation is simple and relatively cheap,and its application demand in all walks of life is growing.The small integrated Raman probe is one of the core components of the hand-held Raman spectrometer.Its performance plays a key role in the performance of the whole detection device.In this paper,the research and market status of hand-held / portable Raman spectrometers are introduced.The Raman spectroscopy principles are explained from the perspectives of classical physics and semi-classical quantum theory respectively.The components of Raman spectrometer are described.A Raman probe suitable for 785 nm excitation wavelength is designed and manufactured.Its aperture is 5 mm and its working distance is 13.5 mm.The optical path of the Raman probe is designed by Zemax software,and the mechanical design of the Raman probe shell is carried out by SolidWorks software.TracePro software is used to simulate the overall optical path.The Raman probe shell was fabricated by 3D printing technology and CNC machining technology,and the Raman spectra of alcohol were tested,which achieves the expected results.Compared with a product in the existing market,the Raman probe has a higher cost performance ratio.Based on the design and implementation of the Raman probe,the preliminary optical system design of the hand-held / portable Raman spectroscopy detection device was carried out,and the assembly of the optical system of the prototype was completed.The Raman characteristic spectra of some drugs(Ketamine,Ma Gu and methamphetamine)were tested by the device,which was basically consistent with the theoretical calculation results.The research results show that the Raman probe designed and implemented in this paper and the portable Raman spectrum detection device based on it are successful.This work has laid a good foundation for the future commercial production of hand-held / portable Raman spectrometers with independent intellectual property rights.