Measurement method of virtual image distance for head-mounted display based on a variable-focus liquid lens

• Shuangjiang Huang, Lihui Wang, Yutao huang, Yuan He, and Shi Bai
• received 03/27/2024; accepted 04/30/2024; posted 04/30/2024; Doc. ID 524353
• Abstract: The distance from the virtual image to the human eye is an important factor inmeasuring the comfort of a head-mounted display (HMD). However, accurately measuring theirdistance is challenging due to the dynamic changes in virtual presence and distance. In thispaper, we proposed a virtual image distance measurement prototype based on a variable-focusliquid lens and derived a virtual image distance calculation model. We built a variable-focusliquid lens experimental platform to verify the method’s correctness. In addition, we proposed animproved optimization algorithm that can efficiently and accurately search for the optimal focallength corresponding to the maximum sharpness moment of the virtual image within the focallength value space. Verified in an experimental scene of 0.5 m to 3.5 m, we observed that theerror between the object image distance and the virtual image distance at the same focal length isabout 5 cm. The proposed virtual image distance measurement method can accurately measurethe distance value of the virtual image in the HMD. This method can be widely used in virtualand augmented reality, especially in the task of constructing realistic scenes.