See-through optical display with freeform mirrors for compact, high-performance augmented reality applications
Institute Reference: 2-11150-13008
Head-worn displays (HWDs) have become critical in augmented reality (AR) and virtual reality (VR) applications. These devices need to be compact and lightweight, with a minimal number of optical elements to ensure wearability and usability. However, reducing optical elements often leads to optical aberrations that degrade the display quality. Traditional designs struggle with the trade-off between field of view (FOV) and image clarity due to packaging and geometric constraints.
The invention introduces a see-through optical display apparatus specifically crafted for head-worn displays. At the heart of this system are two or three tilted, freeform mirrors, carefully designed to provide a high-quality virtual overlay and reduce image distortion, all within a compact design. The constituent mirrors feature non-flat, concave freeform surfaces, optimized to minimize limiting optical aberrations such as coma and astigmatism.
To provide viewing comfort, the apparatus includes an external pupil positioned at the entrance of the observer’s eye. The image source is a microdisplay, such as an OLED microdisplay, offering high-resolution visuals. Additionally, the combiner mirror can be coated with photochromic or electrochromic materials to automatically adjust contrast based on ambient lighting conditions. This design is particularly well-suited for augmented reality applications, enabling users to seamlessly view both real-world surroundings and digital overlays without obstruction.
The system delivers exceptional image quality by using freeform optics, which significantly reduce aberrations such as astigmatism and coma, resulting in near-diffraction-limited performance. Its compact design allows the entire optical system to fit within a spherical volume as small as 14 millimeters in diameter with a field of view between 20-30 degrees, making it ideal for wearable devices. Usability is further enhanced by the external pupil design, which creates eyeboxes up to 5 mm for viewing comfort and flexibility. Additionally, the combiner mirror can be coated with photochromic or electrochromic materials, enabling users to adjust the display’s brightness based on the surrounding lighting conditions.
This technology is well-suited for augmented reality (AR) devices, allowing seamless integration into AR glasses and headsets. It enables real-time digital overlays while preserving a clear view of the surrounding environment. In virtual reality (VR) systems, the apparatus provides high-quality immersive experiences with minimal distortion, significantly reducing eye strain. Additionally, it is ideal for wearable displays used in professional fields such as aviation, medicine, and the military, where see-through displays are critical for enhanced situational awareness and real-time information.
The University of Rochester is open to exploring funded research collaborations, licensing agreements, and other partnership opportunities.