并行差动共焦三维成像方法通过将照明光分割为多光束,实现多点并行探测,解决了传统差动共焦成像中逐点扫描导致的成像效率偏低的问题,是一种理想的快速高精度三维成像方法。然而,在并行差动共焦检测过程中,系统光照不均和光学成像系统的场曲都会引起测量误差。分析了宽场成像过程中不可避免的光照不均及光学系统场曲等因素对并行差动共焦轴向测量的影响,提出了一种宽场误差的修正方法,建立了并行差动共焦轴向测量宽场误差修正的理论模型。实验证明,该方法可以有效地抑制系统光照不均对测量结果的影响,并且校正了光学成像系统场曲等引起的轴向测量误差,保证了并行差动共焦纳米量级轴向测量准确度在全视场范围内的普适性。该方法实施过程简便,适用于其他并行共焦检测方法的误差修正。

The parallel differential confocal three-dimensional imaging method realizes multi-point parallel detection by dividing the illumination light into multiple isolated beams, which solves the problem of low imaging efficiency caused by point-by-point scanning of traditional differential confocal imaging. It is an ideal fast and high-precision three-dimensional imaging method. However, both non-homogeneous illumination and field curvature of an optical imaging system induce errors in the measurement results during the process of parallel differential confocal detection. The effects of inevitable non-homogeneous illumination and field curvature of an optical system during the wide-field imaging process on the parallel differential confocal axial measurement are analyzed, a wide-field error correction method is proposed, and a theoretical model of wide-field error correction is established for the parallel differential confocal axial measurement. The experimental results show that the proposed method can effectively suppress the influence of non-homogeneous illumination on the measurement results and correct the axial measurement error caused by the field curvature of the optical imaging system. It ensures the universality of parallel differential confocal nanometer-scale axial measurement accuracy in the full field of view. The implementation process of this method is simple and convenient, and it is also applicable to error correction of other parallel confocal detection methods.