A Method For Measuring The Refractive Index Of Glass Based On Current Tuned Semiconductor Laser

Refractive index is an important basic parameter of crystal,which is the basis and premise of studying the optical properties of crystal.The refractive index of the same crystal varies with the wavelength,so the measurement value of the refractive index of the crystal plays an important role in the system used.For newly developed materials,optical parameters such as refractive index need to be measured.Some traditional refractive index measurement methods have various limitations on materials,such as size,special shape and so on.These methods are inexpensive and difficult to operate in refractive index measurement.Some methods have a certain range of refractive index measurements,which will lead to their inability to measure the refractive index of some materials.Interferometry has become a research hotspot in recent years because of its wide measurement range and non-destructive,but its development is limited due to technical constraints.Therefore,it is of great significance to develop a high precision and automatic refractive index measurement system in the field of crystal measurement.In this paper,a refractive index measurement method based on current tuned semiconductor lasers is studied and designed.This method consists of two key technologies,namely,linear frequency modulated continuous wave(FMCW)refractive index measurement technology and closed-loop photoelectric phase-locked technology.By improving the traditional Mach-Zehnder interferometer,the FMCW refractive index measurement technology is proposed and designed.This technology can greatly reduce the impact of external environment such as vibration by using triangular frequency modulation.However,because FMCW refractive index measurement technology requires high frequency linearity of laser source,and the current tuned semiconductor laser structure leads to its frequency modulation nonlinearity,which will lead to the broadening of refractive index measurement spectrum and the decrease of resolution and accuracy.Therefore,the non-linearity of the laser is corrected by the photoelectric phase-locked technology,so that FMCW has good frequency modulation linearity.Accurate measurement of glass refractive index is realized by the application of the two techniques.