Design And Development Of Large Field-of-view And High Resolution Head-mounted-display

With the rapid development of virtual reality(VR)and augmented reality(AR)in recent years,high performance head-mounted displays(HMDs)are required.In order to achieve greater immersion,large field of view(FOV)and high resolution are future directions for HMDs.However,in traditional HMDs,FOV and resolution can't be improved simultaneously.The relationship between the two is called “FOV-resolution invariant”,and restricts the performance of HMDs.Compared to existing solutions,optical tiling makes large FOV and high resolution come true at lower cost.At the same time,stereoscopic display can be realized in this way.In the research,a HMD was designed by tiling for VR.The main work accomplished includes the following:1.The eyepiece used for tiling is designed with spherical and aspheric surfaces respectively.The FOV of them is 90(H)x 90 degree(V),and the focal distance is 62 mm.On the other hand,the exit pupil distance(EPD)and eye relief are 14 mm and 6mm respectively.At the same time,the imaging qualities of the spherical and aspheric surfaces are compared by spot diagram and distortion curve.2.The design of the external structure of the prototype and the processing of the lens are completed.After cutting and assembling,the horizontal FOV of monocular eyepiece is113.6°,and vertical maximum FOV is 90°.In order to explain the changes in the parameters for tiling eyepiece,the EPD and eye relief after tiling are discussed which is used to verify the effect of display.3.The distortion models are established according to different display channels,and pre-distortion processing for the image is completed.The radial distortion on the edge of FOV is serious in the single lens,and trapezoid distortion will also appear in the secondary channel,which cannot be corrected by optical means.Nevertheless,according to the result,distorted images are processed to eliminate the distortion of eyepieces,so that eyes can receive better effect.4.Eliminate the influence of seam on the whole picture,and build an experimental device to verify the effect of the prototype.According to the scheme in this paper,the stitching gap will lead to a discontinuous image in transitional region,which will affect the final effect.Analyzing the image of the standard checkerboard through the eyepiece and preprocessing image can be reduced and eliminated this effect.On the other hand,according to the human visual characteristics,a group of images with binocular parallax and extended image of secondary channel are taken,and the continuous image is obtained by panoramic stitching with SIFT algorithm,which is used to verify the effect of head-mounted display.Finally,the previous device is used to verify the display effect of the prototype.