Simulating the effects of statistical characteristics of random phases on speckle noise in computer-generated hologram

Abstract

Computer-generated holography (CGH) is the ideal 3D display technology because we can observe the reconstructed image without 3D fatigue. Holograms are made by computer simulation of light propagation. We used the point-based methods which considers virtual objects as a set of point light sources to calculate object light. Generally, in the recording process of a hologram using the point-based method, the phase of each point on the object surface is randomized in order to diffuse object light, which is called a “random phase”. A random number for implementing a random phase is called a “random phase number”. However, applying a random phase causes “speckle noise” on the surface, due to complicated interference between reflected lights. We examined the relationship between the characteristics of the random phase number and the state of the reconstructed image surface. We focused on the reflection characteristics of the reconstructed image and the speckle noise, in particular. To measure the speckle noise, we used a criterion called “speckle contrast”. In this paper, we examined the relationship between the randomness of the surface phase and the speckle contrast. We confirmed that there are random numbers whose speckle contrast depends on phase variances and random numbers whose speckle contrast does not depend on phase variances