The Development Of Simple Tunable Laser Light Source Module And Its Application

Petroleum products mainly make up of different hydrocarbon compounds, which include rich information about hydrocarbon groups. As absorption peak position and intensity of different hydrocarbon groups in the near infrared spectroscopy is different, near infrared spectral analysis technology can be used in the gas-oil analyzers for on-line analysis. The light source in traditional gas-oil analyzers emits polychromatic light, so that it needs complex system for beam split and has poor stability. Small tunable laser light source module can be used in gas-oil analyzers to simplify the optical path because of its good mono-chromaticity.On the other hand, it avoids the high cost and difficult integration of using a tunable laser source instrument. In this thesis, we use the laser diode to design a tunable laser light source module, which can be integrated in the gas-oil analyzers.Firstly, we analyze the demand for laser source from the constitution of C-H group of oil and gas and the wavelength range of C-H group in the short-wave near infrared spectrum.And we analyze the influence of molecular structure to the group vibration frequency and other factors that affect the group vibration frequency. On the basis of above analysis,technical requirements for laser source are proposed, including the laser wavelength 、resolution and the temperature and light power of the laser source.Secondly, we design the technical indicators and solutions for the laser source. Through analysis of different types of laser and ways of wavelength tuning, we choose the way of wavelength tuning by changing temperature of the diode laser that conforms to the technical requirements and indicators. Then we introduce the constitution of laser light source modules and the detailed design of each module, which include the hardware and software design of temperature control system and optical power control system of the laser source.Finally, we use STM32 chip development platform 、 Realview MDK software development tools and the Labview virtual instrument integrated development environment tobuild a development platform of the control system of gas-oil analyzer source. Then we put forward the mathematical model of temperature control system of the laser source.We analyze the system performance by simulating the temperature control system with different parameters. On this base, we design the temperature controller aiming at the system parameter and simulate its performance. Besides, we use the light source control system development platform to do the experimental test of temperature acquisition and monitoring, as well as the light power control. At last, we put forward improvement suggestions on existing problems.