Abstract: An autofocus system includes a focus light source, an objective lens, a defocus lens, a first image sensor, and a controller. The defocus lens is disposed on the transmission path of the focus light beam, so that a minimum light point of the focus light beam passing through the objective lens deviates from a focus of the objective lens. The first image sensor is configured to receive a focus reflected light beam generated after the focus light beam is reflected by the sample. The controller is electrically connected to the first image sensor. According to a center change of gravity, a position change, or an energy change of a light spot formed by the focus reflected light beam on an image plane of the first image sensor, the controller drives the objective lens or the sample to move, so that the focus of the objective lens falls on the sample.

Abstract: An autofocus system includes a focus light source, an objective lens, a defocus lens, a first image sensor, and a controller. The defocus lens is disposed on the transmission path of the focus light beam, so that a minimum light point of the focus light beam passing through the objective lens deviates from a focus of the objective lens. The first image sensor is configured to receive a focus reflected light beam generated after the focus light beam is reflected by the sample. The controller is electrically connected to the first image sensor. According to a center change of gravity, a position change, or an energy change of a light spot formed by the focus reflected light beam on an image plane of the first image sensor, the controller drives the objective lens or the sample to move, so that the focus of the objective lens falls on the sample.