what is objective lens in microscope

An objective lens is a critical component of a microscope that gathers light from the object being observed and focuses the light rays to produce a real image of the object). It is located closest to the object and is typically mounted on a rotating nosepiece or turret to enable easy selection. The objective lens is responsible for producing the base magnification and is an important component in imaging an object onto the human eye or an image sensor. Each microscope objective is a complex assembly of lenses, and besides contributing to the magnification, it determines the resolution power of the microscope. Objective lenses can be classified based on the objective construction, field of use, microscopy method, performance (optical aberration corrections), and magnification. Most compound microscopes come with interchangeable lenses known as objective lenses, which come in various magnification powers, with the most common being 4x, 10x, 40x, and 100x. The specifications of a microscope objective lens are usually listed on the body of the objective itself, including the objective design/standard, magnification, numerical aperture, working distance, lens to image distance, and cover slip thickness correction.