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Background and objectives: Dermatoscope is an important optical tool for dermatologists. Its illumination system is a key component for high quality visual observation and digital photography. The aim of this study was to evaluate the illumination system of a high-end handhold dermatoscope. Materials and Methods: DermLite DL5 was used for this study. The dermatoscope equipped with sophisticated illumination system for visualization under white, yellow and ultraviolet (UV) light with or without the use of polarization. A fiber optic spectrometer was used to measure the spectra of each lighting mode. A handhold spectrometer was used to measure the color temperature, luminance and chromatic aberration of various lighting conditions under non-polarized, cross-polarized and parallel-polarized modes. The uniformity of each lighting condition was analyzed by pixel analysis of projected digital images. Results: The peak wavelength of the UV LEDs was 377 nm and the full width at half maximum (FWHM) was 21.27 nm. The peak wavelength of the yellow LEDs was 591 nm and the FWHM was 15.5 nm. The color temperature of white LEDs was over 9000 k in several modes, whereas the color temperature of the yellow LEDs varied widely and the color temperature of mixed lighting remained stable at 5000 k. The uniformity of white, yellow and mixed lighting was less than ±10%. Conclusions: The designed higher color temperature of the tested handhold dermatoscope can accommodate the physician's view of skin blood vessels. Good uniformity under different lighting and viewing modes not only satisfies the human eye but also ensure the high quality of dermatoscope digital image of the skin.
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