Lens assembly testing method

A lens assembly testing method, comprising:

• providing a lens assembly comprising a first lens and a second lens optically and mechanically coupled with the first lens, the first lens having a first matching surface, the second lens having a second matching surface, and the first matching surface contacting the second matching surface;
• measuring whether a modulation transfer function value of the lens assembly is in a predetermined range;
• if not, separating the first lens and the second lens, and forming a first coating layer and a second coating layer on the first matching surface to obtain a coated first lens, wherein a color of the first coating layer is different from a color of the second coating layer, the first coating layer completely covers the first matching surface, the second coating layer includes a plurality of dots formed on the first coating layer, shapes of the dots are different from each other, and sizes of the dots are different from each other;
• capturing a first image and a second image of the first matching surface respectively using a first camera module and a second camera module from different directions;
• attaching the first lens to the second lens to obtain a lens assembly, and capturing a third image and a fourth image of the first matching surface respectively using the first camera module and the second camera module from different directions;
• randomly choose one dot from the dots, and determining an actual moving distance of the chosen dot using a 3D-Digital image correlation method according to the first image, the second image, the third image, and the fourth image;
• adjusting a size of the first lens according to the actual moving distance of the chosen dot;
• and
• displaying the adjusted size of the first lens to a user.