Studies of Lenticular Lens Applied in Uniform Illumination for Phone Camera LED Flashlight

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With the much effort of LED technical development, the white light brightness of LED becomes more and more luminous in comparison with the conventional Xenon flash. For the high-level camera phone, LED applied for assistant exposure has become more popular. The white LED has many advantages, such as low power consumption, small size, without capacitors as driver and continuous light, which is very suitable for mobile devices. However, because the LED is a directional light source, the poor illumination uniformity makes the uneven distribution of brightness when capturing images. The photos may show obvious light and shade on various colors. This study shows that second-order optical transfrom can adjusts the distribution of light via the lenticular lens array (LLA) in order to capture the clearer images. In this experiment, we used 5 LPIs, 6 mm x 6 mm LLA sheet equipped with a high brightness white LED. First, put different LPI of LLA sheet samples on optical microscopy to observe its surface morphology, and to understand its actual radius of curvature of the lens. Second, we use TracePro software to analyze the combining a sheet of different LPI of LLA with a high brightness white LED. Finally, it is necessary that measuring the distribution of light intensity and uniformity of illumination. Subsequently, the experimental results show that using the conversion of the LLA can get the good uniformity of illumination and color spatial.