光电工程, 2012, 39 (3): 57, 网络出版: 2012-04-01  

LCD 组件检测中用MTF 评估自动聚焦分辨率的方法

Auto-focus Resolution Estimation Using MTF Method in LCD Components Inspection
作者单位
合肥工业大学 仪器科学与光电工程学院,合肥 230009
摘要
液晶检测设备在自动聚焦后由于焦距变化,成像分辨率也不可避免的发生变化,为此必须提供一种快速评估检测设备实际分辨率的方法。由于检测设备总分辨率为镜头分辨率与相机分辨率的乘积, 因此论文提出先根据相机的各种噪声模型建立相机对比度分辨值,接着用频率渐变的LCD 黑白样条光栅评估不同频率下镜头MTF 的像质退化情况,最后通过分析分辨率与对比度关系,得出相机最高对比度下能够分辨出的经过成像系统像质退化产生亮暗模糊所对应的空间截止频率。实验表明在使用光学检测设备对手机背光源进行缺陷检测时,论文的方法评估实际分辨率>17 μm,用背光源标定样品实际检测后可以得到,对于17 μm 以上缺陷检测设备都能清晰成像,因此结果证明了该方法的有效性。
Abstract
Because of focus changing when TFT inspection device performing auto focus, the resolution of device will inevitably changes. So there is a need to offer a fast estimation method for device’s actual resolution. Since total resolution is the product of camera resolution and lens resolution, at first, camera contrast limit is set up based on all kinds of noise model. Then, LCD white and black bar fringe are used whose frequency changes gradually to estimate lens MTF degeneration. Finally, through relationship between resolution and contrast, the spatial cut through frequency can be calculated by differentiating imaging system’s light dark blur smallest differences at highest camera contrast distinguish condition. Experimental results indicates that when using optic inspection device to examine cell phone background light panel's defects, article's method estimates the actual resolution less than 17 μm , in contrast test, the calibrated sample defects exceeds 17 μm can be photographed clearly using device. The results prove the effectiveness of the proposed method.

李琪, 卢荣胜, 王成顺, 付琰. LCD 组件检测中用MTF 评估自动聚焦分辨率的方法[J]. 光电工程, 2012, 39(3): 57. LI Qi, LU Rong-sheng, WANG Cheng-shun, FU Yan. Auto-focus Resolution Estimation Using MTF Method in LCD Components Inspection[J]. Opto-Electronic Engineering, 2012, 39(3): 57.

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