Abstract
Numerical value of the absorption cross-section ao of ruby R1-line has not been established. Here we propose the value of ao measured by a newly developed laser ray method. The method consists of two preparatory experiments, one the evaluation of absorption coefficient ao and the other the determination of chromium concentration No. Process of determining No is performed by utilizing a nonlinear absorbing characteristics of high power laser. Theory and experiment of the process are shown in detail, and finally get the value (Yo = ao /No for a certain rod, and compare it with previous reports.
