The use of a confocal detection scheme in a dual-beam thermal-lens microscope is presented. The scheme allows the measurement of absorption factors down to 1.2 x 10(-7) in a 0.35-microm3 volume by use of a heating laser power of 100 mW incident upon the sample. Results are presented that prove that a 450-nm axial resolution is possible when a 1.2 water immersion objective lens with a N.A. of 1.2 is used.