An On-Line Digital Optical Bench Tester Based on Conoscopy for Lens Quality Evaluation

This study aims to develop an on-line tester machine for evaluating the image quality of a camera lens that is used in a lens module in a cell phone. This tester is not only suitable for conventional solid lens, but also applicable to the developing tunable liquid crystal lens by using the conoscopy approach to measure focus length and its quality. On the other hand, the approach using a commercial inspection chart along with a automatic feeding machine is also adopted for a quick estimate on the focusing quality that is primarily based on Modulation Transfer Function (MTF). In addition to the MTF, the proposed tester aims to has other functions of measuring Effect Focal Length (EFL), Back Focal Length (BFL), Field of View (FOV), Field curvature, Distortion, Astigmatism, Lateral/Axial Color, the distribution of index of refraction and phase retardation pattern. The constructed tester is capable of measuring varied optical performance indices for the next-generation tunable lens.