为使LED光源实现特定范围内的均匀照明，提出了一种由复合抛物面集光器和自由曲面透镜结合的主次镜两级准直照明设计方法。该方法可将照明系统出射角控制在±5°～±15°范围内，并在目标区域内实现均匀照明。仿真结果显示：系统出射角在±5°～±15°范围内，理想情况下该系统的能量利用率和照明均匀度均可达85%以上；同时，系统的照明均匀度不会随照明距离的改变发生显著变化，在实际应用中可通过改变照明距离来改变光斑大小和光斑照度。

A primary-secondary collimating illumination design method based on compound parabolic concentrator and freeform lens is proposed in order for using LED light source to achieve uniform illumination within a specific region. This method can confine the exit angle of the system in the range of ±5°-±15° and achieve a uniform illumination in the target region. Simulation results show that when the exit angle of the emit light is between ±5° and ±15°, both of the energy efficiency and the illumination uniformity can exceed 85% under the ideal conditions. Also, the illumination uniformity of the system will not change significantly with the alter of illumination distance, and we can change the illumination distance to change the spot size and spot brightness in practice.