Aberration plots for the 64-mm single-element lens. This modulation transfer function (MTF) plot assumes that the cellphone screen maximum resolution is 10 cycles/mm.įigure 4. Finally, the modulation transfer plot (Figure 4, lower right) indicates that the resolution of this system will be reduced from 9.8 cycles/mm on axis, to 3.0 cycles/mm at the field of view of 21 degrees. The distortion plot (Figure 4, lower left) displays how the 9 percent distortion will appear to the eye. In most visual systems, maximum lateral color of less than five minutes is generally acceptable. The remaining distortion will reach about 9 percent at 21 degrees off axis, and the lateral color plot indicates that a residual of 5.7 arc minutes is reached at 21 degrees off axis. As the aberration plot shows, the residual astigmatism will be about 2 diopters of field curvature with 1.0 diopter of astigmatism. The major image quality issues that must be dealt with when creating a new lens design covering the large field of view include: image modulation transfer function, distortion, field curvature-astigmatism and lateral color.īefore a better lens can be designed, however, it’s necessary to analyze and understand the ray trace analysis, distortion and modulation transfer functions for a typical single-element lens (Figure 4). When an increased field of view of 42 × 42° square is presented to the eye, however, the image quality of the optics must improve. Courtesy of Zeiss.įor the single-molded aspheric acrylic lens element presently used in many new VR headsets, the image quality is considered acceptable by most, especially when dealing with a field of view of 36 × 36° square. In the sections that follow, a new lens design is proposed that meets the low cost and weight of the single lens element, while achieving a greatly improved image quality and an increased field of view presented to the eye.įigure 3. The image quality of these systems is limited, however, though this reduced image quality is overcome by the dynamic nature of the 3D motion display presented by the cell phone. The primary advantages of these optics are their low cost and light weight, making them suitable for a large consumer market. Most of today’s VR headsets include simple optics, usually a single molded aspheric acrylic lens for each eye. A 3D bright-color, wide-angle display is not just a fixed image, but it can be a scanning 3D motion display with an audio mode (Figure 3).įigure 2. VR headsets view a pair of 3D images, often displayed on the screen of a modern iPhone or smartphone. The first virtual reality (VR) systems emerged in 2010, and included an updated stereoscopic device. Relative to the early stereoscopes, this yielded a 1.5× increase of the field of view (Figure 2). This resulted in a viewed image with a field of view covering a full 36 × 36° square. In typical viewers of the day, the images were 50 × 50-mm square, viewed with 75-mm focal-length simple optics. Walker.ĭuring the second half of the 1900s, the stereoscope design was fine-tuned to allow the user to view bright, high-resolution color transparencies. This resulted in a 3D field of view that is 24 × 24° (Figure 1).įigure 1. The stereoscope typically included a pair of simple wedge lenses with a focal length of 180 mm, enabling the viewer to see a pair of images in 3D, each being 75 × 75-mm square. Invented by Sir Charles Wheatstone, it was made popular in Europe by Sir David Brewster and in the U.S. In the late 1800s and early 1900s, the stereoscope was the subject of great interest and entertainment in the living rooms of families on both sides of the Atlantic.
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