An intrinsically eye safe approach to high apparent brightness augmented reality displays using computer‐generated holography

Achieving the luminance of real‐world scenes is a challenge for many display technologies. Computer‐generated holography offers a number of advantages, due to both the high optical efficiency and the ability to redistribute available luminous flux to individual points. This is important while displaying sparse content that needs to be clearly perceived against a bright background in augmented reality. In this work, we consider a range of optical architectures and analyze the impact of each element on the overall display luminance. We conclude that the range of holographic projector efficiencies can vary from 50% to 0.05%, with the average of 3%. An example holographic projector with 2% efficiency is built to evaluate the analysis. Using a low‐power RGB laser module, outputting 1.78 mW, a mean luminance of 30,000 cd/m2 has been attained. In the presence of sparse content, peak luminance exceeding 300,000 cd/m2 is demonstrated. Both the calculation and the measurements confirm that by using holography, it is possible to achieve a display that is sufficiently bright to be clearly viewable in daylight, in a manner that can be intrinsically eye safe. The image is projected against daytime sky and appears several times brighter, hence adding visual validation to the analysis. Achieving sufficient display luminance is challenging for many display technologies in augmented reality. Computer‐generated holography offers the ability to redistribute a given luminous flux only to the content of the image, resulting in a significant boost of image luminance. To demonstrate this, we displayed imagery significantly brighter than the daytime sky while using less than 2 mW of optical laser power.