Reflected laser light having a speckle pattern is received in a pixel array. Pixel outputs are combined into series representing pixel intensities along particular dimensions at times t and t+Δt. Centroids for each series can be identified, and vectors determined for movement of centroids from time t to time t+Δt. Crossing points may alternatively be identified for data within each series relative to a reference value for that series, and vectors determined for movement of crossing points from time t to time t+Δt. A probability analysis may be used to extract a magnitude and direction of array displacement from a distribution of movement vectors. A series of data values corresponding to time t+Δt may alternatively be correlated to advanced and delayed versions of a series of data values corresponding to time t. The highest correlation is then used to determine movement.
展开▼
