Truncated cylindrical array plate for mid-air imaging

Mid-air imaging, a visual display technology for augmented reality (AR) that enables multiple people to view images simultaneously without the need for special eyewear, involves the formation of real images in mid-air through various optical elements. This paper presents a novel mid-air imaging optical plate, termed the truncated cylindrical array plate (TCAP). TCAP is composed of transparent cylinders with obliquely truncated ends and mirrors, specifically designed to address issues such as stray light and limited viewing angles in existing mid-air imaging optical elements. We evaluated TCAP through computer simulations and by fabricating a prototype optical element. Ray tracing simulations and stereo matching algorithms demonstrated that mid-air images are symmetrically formed on the side opposite of the light source relative to the TCAP. Furthermore, the simulations indicated that a bright, stray-light-free mid-air image could be achieved within a horizontal viewing angle of approximately \(\pm \, 40 ^\circ \). Experimental evaluation using a handcrafted prototype further confirmed the plane symmetry of mid-air image formation, validating its functionality as a mid-air imaging element. The proposed method is advantageous in systems where stray light is problematic, such as mid-air image interaction systems or optical systems utilizing mid-air imaging elements.