Speckle in laser imagery: efficient methods of quantification and minimization

We describe several techniques for the measurement of speckle noise and efficient implementations for its eradication in laser projection displays. A procedure is given for measuring the magnitude of the speckle noise in terms of a "speckle contrast" parameter. Examples are then cited that reveal the relative importance of spatial versus temporal coherence, and how the speckle contrast can approach "acceptable" values with various hardware configurations. The effectiveness of a component to reduce speckle is defined, for practical consideration, in terms of its insertion loss.