Investigation of the influence of structural parameters of a Fresnel-type lens on the narrowing of light-emitting diode light beams

Abstract

In this study, an influence of the structural parameters of a three-dimensional (3D)-Fresnel-based lens which was designed as a primary optic on the narrowing of light-emitting diode (LED) light beams has been investigated and proposed to gather the emitted light into a narrow-angle light beam. Most conventional LEDs are not able to create a narrow-angle light beam without using a reflector cup or secondary optics, because the LED lighting angle is usually wide (±30 deg from the centerline of the light source). Nevertheless, the energy of the LED light within the range ±16 deg from the centerline of the light source can be greatly enhanced by the focusing effect of a 3D-Fresnel-based lens design as shown in this study. The illumination and the luminous flux of the LED light beam in comparison with the conventional LED have been respectively enhanced up to 61% and 20% respectively. The main contribution of this study is to adjust the height/width ratio of the ladder-shaped structure of a 3D-Fresnel-based lens in order to focus the LED light into a stronger beam, and to meet some specific working circumstances.