Enhanced Helmet Display Optical System Design

Modern helmet display is an optical,mechanical,electrical and arithmetic multidisciplinary fusion technology,which has been widely used in both military and civilian fields.Helmet display optical system as the core part of the helmet display equipment,and its optical performance will directly affect the display effect of the helmet display equipment.In order to make the headset display optical system full-color display with excellent image quality,increase the accuracy of human-computer interaction,and improve the information acquisition dimension of the headset display device,this paper designs an enhanced helmet display optical system with a dual-channel headset display optical system as the core,aided by a line-of-sight tracking lens and a scene recording zoom lens.According to the proposed design of the enhanced helmet display optical system,the basic optical parameters of the visual instrument and the constraints between them are analyzed at the beginning of the design,the aberration characteristics are discussed from two perspectives of geometric aberration and off-axis vector aberration,and several conventional aspheric and free-form surface characterization methods are introduced.The above analysis provides a theoretical basis for the design of subsequent optical systems.In order to making the head-up display system display in full color with excellent image quality,a two-channel head-up display optical model based on a dual-prism structure is proposed.A custom constraint function,combined with a rectangular array pupil adoption algorithm,is used to iteratively optimize the two-channel head-up display optical system.A dual-channel display optical system with a pupil diameter of 8.5 mm,an eyepiece distance of21 mm,a field of view of 45° for the projection channel,and a field of view of 52.5° for the transmission channel was designed.The results of conventional image quality evaluation,eye dynamic image quality analysis and tolerance analysis show that the dual-prism structure-based dual-channel optical model can not only realize full-color display in the visible range with excellent image quality,but also has a simple structure and good processability.In order to increasing the accuracy of human-computer interaction,the principle of line-of-sight tracking is analyzed,the optical design parameters of the line-of-sight tracking lens are calculated according to the design results of the dual-channel head-up display,and the line-of-sight tracking lens is designed in a targeted manner using near-infrared light source-assisted illumination.The lens consists of four optical plastic aspherical lenses with F/2.5 aperture,70° full field of view,optical aberration ≤0.6%,working distance of22.4mm～24.4mm,and total optical length of 4.85 mm.The design results meet the requirements of large field of view,low aberration,ultra-short working distance,and small size for line-of-sight tracking.In order to improving the information acquisition dimension,the recognition distance of the human eye was analyzed and the basic design parameters of the scene recording zoom lens were calculated.Using a variety of optical software alternatively optimized,a reasonable zoom structure was obtained with a zoom range of 14mm～85mm,an aperture of F/4.0,a maximum optical aperture of 16 mm,and a total optical length of 65 mm.A cam curve was plotted by multi-point fitting,and finally a scene recording zoom lens with a clear and stable image plane,a wide zoom range,and a compact size was designed.