光谱共焦三维形貌仪用超大色散线性物镜组设计

Design of dispersive objective lens of large linear chromatic confocal 3D surface profiler

光谱共焦三维形貌仪具有精度高、测量范围大、适应性强等特点,其关键部件是产生轴向色散的物镜,色散物镜轴向色散与波长间的非线性会导致系统整体性能下降。分析了共焦法检测表面形貌的工作原理,以及产生线性轴向色散的条件,根据共焦光学系统的基本设计原理,在预设的设计指标及要求下,完成一个超大色散线性物镜组设计。该色散物镜组采用四级串联结构,在400~700nm光谱范围内达到30mm的色散范围,波长离焦量和波长之间线性度通过线性回归拟合得出判定系数为1,满足色散的线性度要求。

Chromatic confocal 3D profiler has high precision,large measuring range and strong adaptability.The key component is the objective lens with axial dispersion.The nonlinear dispersion of axial dispersion and wavelength of the dispersion objective lens reduces the overall performance of theprofiler.In this paper,by analyzing the principle of confocal method to detect surface topography and the conditions for producing linear axial dispersion,the design indexes and requirements of confocal optical system are given,and a super-dispersive objective lens has been designed.The objective lens has four magnification structures in series dispersing the focus of wavelength between 400 and 700 nm to 30 mm longitudinal range.Through linear regression fitting of the defocusing amount and linearity of the wavelength,it is obtained that the coefficient of determination is 1,greatly improving the linearity of dispersion.