设计了圆环型的灯心结构，在期望张角处布置反射光线照度峰值的办法，得到了表达所期望镜面的一 阶二次微分方程。经过数值求解和函数拟合，确定了球冠结构的反射侧面。当在球冠下方加装圆锥型镜面之后， 进一步提高了广角内的照度均匀度。设计方案将90°张角内的照度不均匀度从设计前的65％改善到了±15％之内。

To get a natural view of an object by lamp in the dark environment, the lamp should produce a uniform illuminance in a large view angle, as the sunshine does. But illuminance produced by a lamp reaches its maximum value in the right front and decreases rapidly sideways. Then a mirror is required to produce an illuminance that increases sideways, compensating the sideway illuminance. A torus illuminant is used for symmetry. To produce a peak illuminance on the edge area where illuminance drops most, the equation that expresses the wanted mirror is given. By numeric calculation and function-fit, a cap sphere is chosen as the mirror. When a cone mirror is added to the bottom of the cap sphere, the illuminance uniformity can be even improved. The warp within 90° view angle is ±15% after design compared with 65% before design.