全景鱼眼光学系统的成像圆通常为完整的圆形，小于感光芯片的垂直方向尺寸，相比长方形芯片，圆形成像圆面积较小，芯片有效像素利用率低。结合全景鱼眼光学系统成像圆小于芯片的特点，介绍一种基于自由曲面设计的全景鱼眼光学系统，可实现椭圆形成像区域，大大提高芯片有效像素的利用率。采用光学设计软件，构建自由曲面模型，运用玻璃镜片加塑料镜片混合构成的方法，通过消像差和控制不同温度场下焦点漂移设计非对称全景鱼眼光学系统的成像区域为椭圆，实现了镜头成像像高X方向接近芯片的水平尺寸，Y方向接近芯片的垂直尺寸。在不考虑制造公差的理想情况下，对于4:3芯片，根据圆和椭圆面积公式可得圆形成像区域的芯片像素有效利用率约为58.9%，椭圆形成像区域的芯片像素有效利用率约为78.5%。仿真和计算结果表明，采用椭圆形成像光学设计比圆形成像光学设计的芯片有效像素利用率提升15%左右。
Abstract
The imaging circle of panoramic fisheye optical system is usually a complete circle, which is smaller than the vertical size of the sensor. Compared with rectangular sensor, the area of circular imaging circle is smaller and the utilization rate of effective pixels of sensor is low. Combined with the characteristic that the imaging circle of panoramic fisheye optical system is smaller than that of sensor, a panoramic fisheye optical system based on freeform surface design was introduced, which could realize elliptical imaging area and greatly improve the utilization rate of effective pixels of sensor. The freeform surface model was built by using the optical design software, which was composed of glass lens and plastic lens. The imaging area of the asymmetric panoramic fisheye optical system was designed to be ellipse by eliminating aberration and controlling the focus shift under different temperature fields. The X direction of the lens image height was close to the horizontal size of the sensor, and the Y direction of the lens image height was close to the vertical size of the sensor. Without considering the manufacturing tolerance, according to the circle and ellipse area formula, for sensor of 4:3, the effective utilization rate of sensor pixels in the circular imaging area was about 58.9%, and that in the elliptical imaging area was about 78.5%. Finally, the simulation and calculation results show that the utilization rate of effective pixels of the sensor with elliptical imaging optical design is about 15% higher than that with circular imaging optical design.
关键词
椭圆形成像区域 /
自由曲面 /
有效像素利用率 /
全景鱼眼光学系统
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Key words
panoramic fisheye optical system /
elliptical imaging area /
utilization rate of effective pixels /
freeform surface
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