Angular spectrum method for simulation and analysis of ground glass produced laser speckle pattern

Abstract

The feature size of holographic diffuser is an important parameter which affects the display resolution when the holographic diffuser is used as an exit-pupil expander device in head up display. However, there is currently a lack of relevant research work on it. Here, we derive the amplitude and phase properties of the scattering light based on a statistical model of the surface undulations of ground glass. Combining with angular spectrum diffraction theory, a method for accurately simulating the speckle pattern is developed. The speckle patterns in the far-field and near-field diffraction areas of light passing through ground glass is calculated, then compared with estimation and experimental results. The comparison shows that the speckle feature size obtained by the traditional estimation method is quite different from the experimental results in the nearfield diffraction area. While the results obtained by our simulation method is in good agreement with the experiment in both near-field and far-filed diffraction areas. This work provides an effective method for the design and preparation of small feature size holographic diffuser elements.