紫外工业检测光学系统设计及公差分析

Design and Tolerance Analysis of UV Industrial Inspection Optical System

为满足紫外波段对产品的检测与识别需求,设计出一套宽光谱、较大视场、较大光圈、结构紧凑的紫外工业检测光学系统,要求紫外工业检测镜头的工作波长为240~320nm,全视场角为40°,系统焦距为15mm,F数为3,系统总长小于60mm。该系统采用MS20-UV型紫外电荷耦合器件(CCD),其分辨率为1920pixel×1080pixel,像元尺寸为5.48μm×5.48μm。从成本及像质方面综合考虑,最后采用全球面透射式且非胶合方案。该系统采用反摄远物镜为初始结构,利用Zemax光学软件进行设计;结合工艺要求对设计结果进行公差分析,确定公差误差的来源,并进行相关结构的优化,给出优化前后的蒙特卡罗模拟结果;最终设计出全视场调制传递函数(MTF)在100lp/mm范围内均大于0.5、场曲小于0.1mm、畸变小于1.3%的紫外镜头。与其他紫外系统相比,设计的系统具有成像质量高、分辨率高、畸变低、焦距短、结构紧凑的优点。

In order to meet the detection and identification requirements of products in the ultraviolet （UV） band, we design a set of UV industrial inspection optical system with wide spectrum, large field of view, large aperture and compact structure. Its design requirements are： UV industrial inspection lens with working wavelength of 240- 320 nm, full field of view angle of 40°, system focal length of 15 ram, F number of 3, and total system length of less than 60 mm. The system uses MS20-UV type UV charge coupled device （CCD） with a resolution of 1920 pixel× 1080 pixel, pixel size of 5.48 μm×5.48 μm. Considering the cost and image quality, the design adopts the global transmissive and non-glued solution. The system uses an anti-telescopic objective lens as the initial structure and uses Zemax optical software to design. The tolerance analysis is performed on the design results to determine the source of the tolerance error in combination with the requirements of the process requirement. And the relevant structure is optimized. Monte-Carlo simulation results before and after optimization are compared. Finally, the UV lens is designed with the modulation transfer function （MTF） of full field of view of more than 0.5 in the range of 100 lp/mm, the field curvature of less than 0.1 mm and the distortion of less than 1.3%. Compared with other UV systems, this system has the advantages of high image quality, high resolution, low distortion, short focal length and compact structure.