The main goal of this work is the study of latent fission track structure (or the associated defects density) analyzing the geometry evolution of etched tracks. In this way, measurements of diameter and cone angle for 235U fission tracks reaching soda-lime glass surface with normal incidence were made. These glasses were etched since very short etching time up to times around standard etching used for optical microscopy. The measurements were obtained using an Atomic Force Microscope (AFM) and a Scanning Electron Microscope (SEM). Employing a geometrical model to describe track evolution in isotropic materials it was possible to conclude that the defect density in latent tracks can be considered constant along the fission fragment trajectory. © 2009 Elsevier Ltd. All rights reserved.449-10746749Fleischer, R.L., Price, P.B., Walker, R.M., (1975) Nuclear Tracks in Solids: Principles and Applications, , University of California Press, Berkeley p. 626Guedes, S., Iunes, P.J., Hadler Neto, J.C., Bigazzi, G., Tello, C.A., Alencar, I., Palissari, R., Moreira, P.A.F.P., Kinetic model for the relationship between mean diameter shortening and age reduction in glass samples (2005) Radiat. Meas., 39, pp. 647-652Ho, J.P.Y., Yip, C.M.Y., Koo, V.S.Y., Nikezic, D., Yu, K.N., Measurements of bulk etch rate of LR115 detector with Atomic Force Microscopy (2002) Radiat. Meas., 35, pp. 571-573Nikezic, D., Ho, J.P.Y., Yip, C.W.Y., Koo, V.S.Y., Yu, K.N., Feasibility and limitation of tracks studies using Atomic Force Microscopy (2002) Nucl. Instr. and Meth. B, 197, pp. 293-300Nikezic, D., Yu, K.N., Calculations of track parameters and plots of tracks openings and wall profiles in CR-39 detectors (2003) Radiat. Meas., 37, pp. 595-601Singh, S., Sandhu, A.K., Prasher, S., Pandey, O.P., Effect of neutron irradiation on etching, optical and structural properties of microscopic glass slide used as a Solid State Nuclear Track Detector (2007) Radiat. Meas., 42, pp. 1328-1331Somogyi, G., Szalay, S.A., Track-diameter kinetics in dielectric track detectors (1973) Nucl. Instr. and Meth. B, 109, pp. 211-232Yasuda, N., Yamamoto, M., Miyahara, N., Ishigure, N., Kanai, T., Ogura, K., Measurement of bulk etch rate of CR-39 with Atomic Force Microscopy (1998) Nucl. Instr. and Meth. B, 142, pp. 111-116Ziegler, J.F., (2006) SRIM 2006.2, , http://www.srim.org