Disclosed lens designs enable uniform light distribution without hot spot, achieving wider transfer functions of light compared with traditional lenses, with a benefit of reducing the number of light sources needed and overall cost for direct-lit backlight device. A disclosed lens includes a beam shaping element on the top thereof and a backlight device incorporating the lens and the beam shaping element to eliminate a light hot spot produced by the backlight device and obtain a uniform light distribution at the illumination field. The disclosed lens is especially useful when extremely wider transfer function or extremely thin backlight is needed.