Measurement of low optical absorption in highly scattering media using the thermal lens effect J.A. Olivares, A. García-Valenzuela, F.L.S. Cuppo, F. Curiel, G. Ortiz et R.G. Barrera J. Phys. IV France, 125 (2005) 153-156 DOI: 10.1051/jp4:2005125035