An optical tracking system is disclosed that provides more precise tracking and better performance in an optical mouse. It involves provides a collimated laser, and imaging a reflection of the collimated laser, such that the reflection has a substantially linear phase gradient. The reflection of the laser includes a pattern of speckles due to optical interference effects. The speckles are imaged such that the substantially linear phase gradient restricts any variation in intensity of the imaging of the speckles during a translating motion of the reflection, thereby providing superior tracking performance.