Evaluating the contrast in speckle patterns produced by laser projection displays can facilitate the development of methods to suppress such imperfection. Computer simulations were first conducted to characterize the contrast (Cgs) of fully developed speckle patterns with spatial factor k and power factor r. Results showed that 0.1≤r≤2.0 and k≥4.0 were required to obtain a Cgs with less than 5% error. Experimental results, however, revealed that a power factor within the range 0.5≤r≤2.0 was needed, meaning that the speckle dimension was at least four times the pixel pitch and the largest speckle intensity was of the order of magnitude of the saturation level of the camera. The method proposed here is that the spatial factor be determined by adjusting the distance between the object and the camera, and the power factor be determined by monitoring the real-time histogram representing the speckle pattern.
© 2014 Optical Society of AmericaPDF Article