大口径硫系玻璃内部缺陷检测物镜设计及实验验证

Optical design of inspection lens for internal defect of largediameter chalcogenide glasses and experimental verification

大口径硫系玻璃在军事及民用高分辨率红外夜视成像领域有着重要的应用价值。现阶段缺少针对大口径硫系玻璃内部缺陷(包括条纹、杂质和裂纹等)进行量化评价的检测技术,因此硫系玻璃的品质控制成为了限制其大范围发展的瓶颈之一。针对课题组大口径硫系玻璃的透射光谱特性以及现有的近红外照相机的光谱响应特性,提出了一种工作在近红外波段的大口径硫系玻璃内部缺陷检测技术并设计成像镜头,镜头包含了使用K9、F6玻璃的三片双胶合透镜,有效焦距为200 mm,在近红外波段0.95~1.05μm实现消色差,成像质量接近衍射极限。根据镜头特点搭建了大口径硫系玻璃内部缺陷测试装置,实验验证了镜头的分辨率与设计要求相符,并可针对大口径硫系玻璃的各种内部缺陷进行有效检测。

Large diameter chalcogenide glasses play an important role in developing high resolution infrared imaging systems for various military and civil applications. However, it lacks an effective measure for inspecting the internal artifacts(including non-uniformity of refractive indices, impurities, and cracks) of bulk chalcogenide glasses and thus the application of such glasses was limited. A near infrared lens was developed for inspecting the internal artifacts of large diameter chalcogenide glasses. Considering the spectral characteristics of the chalcogenide glasses and a currently available infrared camera, the performance of the lens was optimized for the spectral band of 0.95-1.05 μm. A group of three achromatic doublets was utilized to eliminate the chromatic aberration and realize an imaging performance that is close to a diffraction-limited system. Off-the-shelf glasses of K9 and F6 were used in this design.The proposed lens was tested in experimental settings for inspecting internal artifacts of chalcogenide glasses. According to the experimental results, the resolution of the proposed lens matches the design parameters well and many kinds of internal artifacts of chalcogenide glasses, including non-uniformity of refractive indices, impurities, and cracks, are clearly observed in images captured by the proposed lens.