A large-aperture biocular virtual reality head-up display system with spatial multiplexing and dual focal planes using birdbath optical structure

The concept of spatial multiplexing and dual focal planes has emerged as a prominent research focus in the field of near-eye display and optometry. The development of a biocular optical near-eye head-up display featuring spatial multiplexing and dual focal planes capabilities poses a significant challenge. This study introduces a design method for a large-aperture biocular near-eye head-up display based on birdbath optical structure. The system consists of 10 optical components, a transparent LCD display, and a high-brightness LCD display with a specially designed backlight, which magnifies the images displayed by the two LCD displays. The optical system comprises a beam splitter, a curved reflective mirror, 8 single lenses, a transparent LCD display, and a high-brightness LCD display with a specially designed backlight. This system is designed to amplify the visual content shown on the paired LCD displays. In contrast to conventional multifocal optical approaches, the system outlined in this study forgoes the beam-splitting technique. Instead, it places the two LCD displays co-axially in space to achieve spatial multiplexing. Simultaneously, both LCD displays are illuminated by the same backlight module. This approach increases the flexibility of placing transparent LCD displays in three-dimensional space while diminishing the brightness of transparent LCD displays to amplify the defocus stimulation effect within this optical path. Both focal planes are based on 5.5-inch LCD displays. The entire optical system offers a diagonal field of view measuring 30°, an eye box of 100 mm × 70 mm, and an eye relief of 225 mm.