Optimization of the Raman spectroscopic method for crystal orientation and residual stress of aluminum oxide

A half-wavelength plate was set in the common light path to simultaneously alter the polarization directions of both incident laser and scattered Raman signals, and the distribution functions of the polarized Raman scattering intensity about the polarization rotation angle and the crystal orientation angle were deduced. The measurement accuracies of crystal orientations when using different correction methods of light intensity were compared, and on that basis, a measurement system and a measurement method for the crystal orientation of 95% aluminum oxide (Al 2 O 3 ) were established, which improved the accuracy and handleability of crystal orientation detection. Then, the number of Raman peak shifts needed for solving equations was reduced to three by studying the simplification method of stress fields, exploring the Raman selection method, and introducing the differential evolution algorithm. In this way, the method that can calculate the residual stress in the absence of peaks in Raman spectroscopic tests was proposed. The established test system and method were also adopted to test single-crystal and polycrystal Al 2 O 3 samples with known stress. Results show that the established stress measurement method is highly reliable and accurate. Finally, the residual stress distribution in the ceramic side of 95%Al 2 O 3 /4J33 brazed joints was also tested.