This motivates making the lens as large as possible so that this problem is reduced. As the position of the pupil over the lens changes laterally, the distortion varies and becomes asymmetric. The situation is not perfect because as the eye rotates, the pupil moves along a spherical arc. If the eye is not centered on the lens, then asymmetric distortion arises. Some headsets offer IPD adjustment, which allows the distance between the lenses to be adjusted so that they are matched to the user's eyes. Even if the lens distortion is perfectly circularly symmetric, it must also be placed so that it is centered over the eye. This means that the amount of distortion depends only on the distance from the lens center, and not the particular direction from the center. One assumption is that the distortion is circularly symmetric. Whether small or large, the distortion can also be corrected in software. One unfortunate side effect of Fresnel lenses is that glaring can be frequently observed as light scatters across the ridges along the surface. A Fresnel lens is used, for example, in the HTC Vive VR headset. Another way to greatly reduce this problem is to use a Fresnel lens (see Figure 7.14), which more accurately controls the bending of light rays by using a corrugated or sawtooth surface over a larger area an aspheric design can be implemented as well. For example, digital light processing ( DLP ) technology directly projects light into the eye without using lenses. How can this problem be solved? Significant research is being done in this area, and the possible solutions involve different optical systems and display technologies. The convex surface on the top lens is implemented in the Fresnel lens shown on the bottom. A Fresnel lens (pronounced like ``frenelle'') simulates a simple lens by making a corrugated surface.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |