Abstract: With small rectangular cross-section incident light beam(SRCSILB) focused by a flat-convex lens and all the lights propagating through a straight-line-type optical wave-guide cell(OWGC) by total reflection within its meridian planes,an expression was induced for the calculation of absorbance Aof OWGC.According to this expression and a number of given parameters,numerical calculations were conducted and Fig.3 was drawn.Very good linearities of the dependence of Aon the concentration Cof specimens and the length l of the OWGC are obtained for all the linear lines.These results indicate again that Wei Lei et al.and Dasgupta's conclusion of nonlinearities between A and Cor l is not unconditionally tenable.

Key words: Optical wave-guide cell, Total reflection long capillary cell, Expression of absorbance