Autofocusing Optical Instrument Using Multiple Sharpness Functions

The patent divides the focusing evaluation into multiple independent sharpness functions (e.g., different spatial frequency bands, different image regions, or different focus metrics). Each function evaluates sharpness independently, and the final focus decision is made by combining results from multiple functions through majority voting or weighted aggregation. This segmentation allows the system to overcome secondary maxima in individual functions by relying on consensus across multiple evaluation criteria.

The patent implements dynamic adjustment of the focus increment size based on the current focusing state and evaluation results. When the system detects that it is far from the optimal focus position (e.g., through consistent directional gradients across multiple sharpness functions), it uses larger increments to accelerate convergence. As the system approaches the optimal position, the increment size is automatically reduced to allow precise settling, preventing overshooting. This dynamic adaptation optimizes both focusing speed and accuracy throughout the focusing process.