Silicon flat convex lenses possess magnification. Convex lenses are divided into size at two times the focal length, and real and imaginary at one times the focal length.
Parallel light (such as sunlight) parallel to the main optical axis (convex lens two spherical sphere of the line called the main optical axis of this lens) into the convex lens, light in the two sides of the lens after two refractions, concentrated in the axis of a point, this point is called the focal point of the convex lens (notation F, English: focal point), convex lens in the mirror on each side of the real focus, such as for thin lenses, the two focus to the centre of the lens is roughly the same distance. In the case of a thin lens, the distance between the two focal points and the centre of the lens is approximately equal. The focal length of a convex lens is the distance from the focal point to the centre of the lens, usually expressed as f. The more the spherical radius of the convex lens, the more the focal length of the lens. The smaller the spherical radius of a convex lens, the shorter the focal length. Convex lenses can be used for magnifying glasses, glasses for presbyopes and farsighted people, lenses for cameras, film projectors, slide projectors, microscopes, telescopes, and so on. Main axis: the straight line passing through the two spherical centres C1.C2 of a convex lens is called the main optical axis of the convex lens. Centre of light: the centre O of a convex lens is the centre of light of the lens. Focus: Light rays parallel to the main axis pass through the convex lens and converge at a point F on the main optical axis, which is the focus of the convex lens. Focal length: the distance from the focal point F to the centre of light O of the convex lens is called the focal length and is expressed as f. Object distance: The distance from the object to the centre of the convex lens is called the object distance and is expressed as u. Image distance: The distance from the image of an object through a silicon flat convex lens to the centre of the convex lens is called the image distance and is expressed as v.

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