VR (Virtual Reality) is a kind of head-mounted display device that uses virtual reality technology to realize the immersive experience of the virtual world, which is accepted and loved by more and more people. As a cutting-edge technology product, it can simulate the real world and provide an immersive experience, while also providing a variety of functions such as virtual games and entertainment. With the further popularization of VR devices, consumers have put forward higher requirements for lightness, thinness, imaging quality, and wearing experience. Among them, thinness is the core direction of the development of VR headsets.
VR optics are a key component of VR devices. The development of VR optics has gone through three stages: aspheric lenses, Fresnel lenses, and folded optical paths (pancake), and the volume and weight have been decreasing. Although the current VR equipment on the market is still dominated by Fresnel lenses, Pancake has gradually been recognized and adopted by major manufacturers because of its major breakthrough in thinning and lightening, and is regarded as the preferred solution for the new generation of VR nearsight.
The working principle of Pancake is based on the polarization characteristics of light, using a lens system of transflective and semi-reflective polarization films to fold the optical path, so that the light can fold back multiple times between the lens, the phase delay and the reflective polarizer to form a longer optical path, thereby reducing the required distance between the wearer's eyes and the display, and realizing the thinning of VR glasses.
Compared with traditional aspheric lenses and Fresnel lenses, the functional advantage of Pancake module lies in the folding of the optical path, and the optical film plays a vital role in imaging, so the quality of the film material and the film process correspondingly constitute the core of the technology. At the same time, the optical path design of the Pancake solution is complex, and the assembly and alignment adjustment requirements are high, and subtle differences will lead to changes in the optical path of the optical module as a whole. Therefore, it is necessary to carry out strict quality inspection on the assembled pancake module in the way of non-ring sample to ensure that the thickness of the optical film after the film meets the design requirements and the overall assembly of the module is correct.
The innovative combination of high precision and high resolution of the ZEISS industrial CT measuring machine METROTOM 800 (HR) enables efficient scanning of the Pancake module and the rapid inspection of the gap between the lens and the edge of the lens barrel as well as the thickness of the optical film. At the same time, the measurement results meet the requirements of high-precision traceable measurement, which is accurate and reliable. Through AMMAR correction, the artifacts caused by the presence of multi-material parts in the Pancake module are effectively reduced, and the image quality is better and the details are more obvious, further improving the accuracy of the measurement results.
ZEISS has a rich product line including microscopes, blue light scanners, CMMs, industrial CT, and a full range of quality solutions to help customers solve the challenges and pain points that may be faced in the process of upgrading new technologies for VR headsets.