In the early stages, focusing was mainly performed by manually adjusting the distance between the lens and the object, followed by evaluating the imaging quality through visual observation. Manual focusing was highly susceptible to external disturbances, which compromised accuracy and reduced operational efficiency. Autofocus technology is designed to determine the object-to-image plane distance or accurately position optical elements along the optical axis, making it an advanced, high-precision positioning technique. Driven by rapid technological progress, autofocus systems have evolved toward miniaturization and high-level integration. Today, autofocus systems are indispensable core components in portable imaging devices, including digital cameras, smartphones, and other mobile imaging platforms.