Measurement of Stresses Using Fluorescence in an Optical Microprobe: Stresses around Indentations in a Chromium‐Doped Sapphire

Abstract

A technique for measuring stress (positive and negative) with a lateral spatial extent of approximately 2 μm is introduced. The technique, implemented using a Raman microprobe, is demonstrated with measurements of the frequency shift of the sharp, R‐luminescence lines (2Ā and Ē to 4 A 2 radiative transitions) in, and around, a hardness indentation in a 0.06‐wt%‐chromium doped sapphire. From the observed frequency shifts the stresses in regions sampled in the hardness impression, in the complex stress field surrounding it, and at the tip of a crack are measured.