Here in, a high-quality automotive camera lens was developed based on an ultra-precision diamond turning core and cyclic olefin polymer (COP) injection molding process. To improve surface roughness and achieve the accuracy of plastic injection molding lens, systematic mold core machining process was developed and demonstrated using the diamond turning machine. The cutting tool path was generated by using NanoCAM 2D, and it was partly revised to prevent interference between the cutting tool and the workpiece. After the initial machining using the generated tool path, the compensation-cutting process was conducted based on the measured surface profile of an initially machined surface. After two times of compensation machining, the fabricated core mold showed a shape error of 100 nm between peak to valley (PV) and Arithmetic mean roughness (Ra) of 3.9 nm. The performance of the fabricated core was evaluated using an injection molding test. Injection molded aspheric plastic lens showed contrasts that were higher than 55% at 0.0 F, 30% at 0.3 F, and 20% at 0.7 F without any moiré phenomenon that meets the specification for automotive vision module with 1MP and 140° field of view.

In mobile phone cameras, usually a voice coil motor (VCM) is used as a micro-positioning device for the image autofocus (AF) because of its low cost, simplicity, and reliability. Measuring the actual displacement of the VCM is important when we assemble the camera and test the AF performance for distant objects. In this paper, we propose using a confocal displacement sensor for calibrating the VCM displacement, where the axial chromatic aberration of a confocal objective lens is used to measure the target position. The tolerance angle for the dynamic tilt of a VCM increased up to ±15o because of the large numerical aperture of the confocal objective lens, which increased the stability of the repeatable in-line inspection. We compared the measurement robustness of the confocal displacement sensor with that of the laser displacement sensor in a mass production line to verify its performance superiority.