Calculation model for the design of volume holographic optical elements and the application to see-through near-eye display

Ching-Cherng Sun^1,2*, Chi Sun², Shiuan-Huei Lin², Chih-Yuan Cheng¹, Yeh-Wei Yu¹, WEI-CHIA SU³, WEN-KAI LIN¹

¹Department of Optics and Photonics, National Central Univ, 中壢市, Taiwan
²Department of Electrophysics, National Yang Ming Chiao Tung University, 新竹市, Taiwan
³Department of Physics, National Changhua University of Education, 彰化, Taiwan

* Presenter:Ching-Cherng Sun, email:ccsun@dop.ncu.edu.tw

Volume Holographic Optical Elements (VHOEs) are indeed of significant interest due to their unique properties in wavefront generation and their potential applications in various fields, including mixed reality (MR) glasses. VHOEs can be used to manipulate and shape light waves, making them suitable for creating see-through displays and other optical applications. It is important to understand their diffraction properties and limitations, especially when working with thin holographic optical elements.
One challenge with VHOEs of limited thickness is their ability to satisfy the strong Bragg condition for efficient holographic diffraction. When the thickness is insufficient, negative-first-order (NFO) diffraction can introduce unwanted wavefronts, which may degrade the performance of the optical element.
Calculating the diffraction properties of VHOEs can be a complex task, especially when the incident wavefront is not perfectly collimated. The behavior of VHOEs depends on various parameters, including the hologram's thickness, the incident angle of light, and the wavelength of the light being used. Accurate modeling and simulation are essential to design VHOEs that meet specific requirements.
In this paper, we propose a novel calculation model for determining the design parameters of VHOEs. This model may help in understanding the behavior of VHOEs under various conditions, including non-collimated wavefronts. By optimizing the holographic optical element design, we can potentially minimize the effects of NFO diffraction and enhance the performance of VHOEs in applications like see-through near-eye glasses for mixed reality.
The practical demonstration of VHOEs in near-eye glasses is an exciting prospect. These glasses could benefit from improved optical performance, reduced aberrations, and better see-through capabilities. The performance evaluation and discussion in the paper will be crucial in assessing the viability of VHOEs in mixed-reality glasses and the extent to which they can enhance the user experience.

Keywords: volume holographic optical element, see-through near-eye glasses, optical diffraction