Design of off-axis reflective holographic optical elements in a holographic near-eye display system.

Holographic optical elements (HOEs) span a wide application, such as virtual reality and augmented reality displays. However, due to the complex aperiodic structures in lens-type HOEs, the phase design faces difficulties in aberration optimization. Here, we present a method for the design of the off-axis reflective lens-type HOE. Considering the varying degrees of aberrations introduced by the varying object distances across different regions of the object plane, a straightforward yet effective local aberration compensation method is carried out through superimposing different mutually perpendicular cylindrical lens phases at different positions of the HOE. The optimized phase distribution of the HOE can be directly obtained for fabrication like holographic printing. The numerical results show that the field curvature (FC) and the interval of the imaging distance between the meridional plane and the sagittal plane are significantly reduced to 1% of their initial values, and the astigmatism is alleviated. The optical experiments are conducted using two spatial light modulators (SLMs), and the experimental results are in good agreement with the optimized ones. It is expected that the proposed method could be further applied for the development of holographic near-eye display (NED) devices.