The track etch detector, CR-39, in common use is the most sensitive to recording charged particles. The CR-39 polymer samples were irradiated with alpha particle at different energies (2.17 MeV and 3.95 MeV) and fixed fluence followed by chemical etching with different times (1.50, 3.00 and 6.00 hrs). The formed tracks in CR-39 due to irradiations were visualized by using etching technique. The optical properties of CR-39 polymer after etching processes were studied with ultraviolet-visible (UV-vis) spectroscopy. Moreover, the optical band gap energy was calculated for the different etching times (1.50, 3.00 and 6.00 hrs). The average value of the track diameter of irradiation at 2.17 MeV and etching time 1.5 hr is fairly large compared with its value at 3.95 MeV. This is due to the production of defect levels in the band gap of polymer at the 2.17 MeV. The virgin and 2.17 MeV samples at 3.00 and 6.00 hrs have the same optical behavior resulted in the etching solution at those etching times has reached the end of the alpha particle path and progress in all the directions in the bulk of CR-39 with the same rate.