The treatment using UV radiation and photons has more energy and can have important and often profound effects on the properties of path detectors behind electrons or other particles that they may not be able to monitor.The effect of the UV radiation is studied to investigate the optical properties of CR-39 polymer. The measurements of FTIR spectroscopy show maintenance of the main vibratory band resulting from the irradiation times. The optical absorption spectrum of UV / VS indicates main alteration in the optical energy gap with irradiation times. From the results, we found that by increasing the irradiation time of CR-39 by UV- lamp due to increase in the sensitivity of the detector and improvement of its properties thus due to the safe used of these detectors. FTIR spectra shows the conservation of the distinctive spectral peaks related to the monomer of polymer before and after exposing to different intensities of UV-lamp. From this results, the CR-39 detector ultraviolet irradiated were conformed to be very sensitive to UV radiation.