Focusing method, optical imaging system, sequencing system, and medium

A focusing method, applicable to an optical imaging system, wherein the optical imaging system comprises a carrying platform and an imaging apparatus, wherein the carrying platform is configured to carry a sample, and the sample comprises a plurality of axially movable surfaces;

• at least one of the plurality of axially movable surfaces is loaded with an object of interest, and the surface loaded with the object of interest is defined as a target surface for imaging;
• the imaging apparatus comprises a driving module, a focusing module, an objective lens, and an image sensor, and the focusing module comprises a light source and a focusing sensor;
• and wherein the method comprises:
• enabling the light source to emit a first light beam onto the sample;
• enabling the driving module to drive the objective lens along an optical axis thereof to move toward the sample at a first step, and acquiring, after each movement, a first position of the objective lens and first light beam information reflected from a surface of the sample and received by the focusing sensor;
• identifying, based on the first position and the first light beam information, an optical focusing position of the objective lens for the target surface;
• and
• enabling, based on the optical focusing position, the driving module to drive the objective lens to move along the optical axis thereof at a second step, acquiring, after each movement, a second position of the objective lens and enabling the image sensor to image the object of interest on the target surface to form a first image, and using the second position of the objective lens corresponding to the first image having optimal image quality as a first image focusing position of the objective lens for the target surface.