Apple Patent reveals future Glasses with a Pupil Expansion feature that increases the field of view of a Projected Image
Today the US Patent & Trademark Office published a patent application from Apple that relates to future glasses and/or an HMD. More specifically, the patent covers a pupil expansion feature that is designed to increase the field of view of a projected image onto the optical lens that provides a quality image for AR applications.
Patent: Pupil Expansion
The first of Apple's series of eyewear patents is titled "Pupil Expansion." It generally relates to optical reflective devices, and more specifically to expanding light beams within optical reflective devices.
Apple notes in their patent filing that one or more holographic optical elements may be used in a waveguide of optical head-mounted display (HMD) device. An HMD device is a wearable device that has the capability of reflecting projected images and may facilitate a user to experience augmented reality.
Head-mounted displays typically involve near-eye optics that project virtual images. In the past, technical limitations of HMDs have resulted in experience impediments including reduced image quality and increased weight and size.
Past implementations have included conventional optics to reflect, refract or diffract light, however, the designs tend to be bulky. Additionally, conventional mirrors and grating structures have inherent limitations. For example, a conventional mirror may have a reflective axis that is necessarily coincident with surface normal, imposing a suboptimal mirror orientation, or hindered reflective output at the mirror.
Apple's invention generally relates to one or more improved methods, systems, or devices for expanding light beams from an entrance pupil to an exit pupil (i.e., pupil expansion). The methods, systems, or devices may employ one or more pupil expanders or pupil expansion techniques in an optical device or system to enable an increased field of view (FOV) of a projected image.
Apple's patent FIG. 1 below is an illustration of an HMD device in which the principles included herein may be implemented. The HMD device #100 may include eyewear or headwear in which a near-eye display (NED) #105 may be affixed in front of a user's eyes.
Apple used this particular patent figure in a supporting patent that we covered back in April relating to dispersion compensation structures that allow a user to experience quality AR imagery.
Apple's patent FIG. 3 below is a diagram of an optical system incorporating two-dimensional skew mirror exit pupil expansion techniques. The optical system (#300) may be utilized in an HMD, augmented reality (AR), or virtual reality (VR) application such as, but not limited to, the HMD #100 of FIG. 1 above.
Apple's patent FIG. 8B above illustrates an example of an optical lens #800-b that supports pupil expansion.
Apple's patent application 20200192101 that was published today by the U.S. Patent Office was filed back in Q4 2019. Apple's patent is rich in technical details and for those interested in digging deeper into this invention could do so here. Considering that this is a patent application, the timing of such a product to market is unknown at this time.