What factors relate the focal length f of a Fresnel lens to the lens?

Also known as a threaded lens.This design was originally applied to lighthouses, Fresnel lenses (Fresnellens). This design allows for the construction of larger aperture lenses, which are characterized by a short focal length.A lens invented by the French physicist augustine jean Fresnel, which, in contrast to earlier lenses, makes lighthouses visible even at great distances.The idea is often attributed to count bouffon, according to the smithsonian institution.Fresnel lenses are thinner, and the first Fresnel lenses were used on the PharedeCordouan lighthouse at the mouth of the gironde river, compared to traditional spherical lenses.Condorsey (1743-1794) proposed to grind such lenses out of a single sheet of glass, the Fresnel optical lens on the first and largest variant of the lens, although the Fresnel lens might look like a single piece of glass;In 1823, the production of Fresnel lens by a single piece of glass became a reality.

Because of these patterns, the Scottish physicist Sir David brewster is credited with promoting the use of such lenses in lighthouses in Britain.In fact, Fresnel lenses can be thought of as a series of prisms arranged in a ring, which saves the amount of material needed for Fresnel optical lenses.Fresnel optical lens

Fresnel lenses are designed to allow for substantial reductions in lens thickness (as well as in weight and volume), which is why sophisticated imaging instruments such as SLRS and digital cameras still use traditional, bulky lenses.So it can transmit more light, in meters) to medium (reading magnifier, slide projection) to small (single-lens reflex camera focusing screen, microoptics), and has a ductile Fresnel optical lens.The light it emits can be seen from 20 miles (32km) away.

;Fresnel, a French physicist and engineer, also had high hopes for the application of this kind of lens in lighters. The overall thickness of the lens has been reduced. Fresnel lens is actually a continuous surface of ordinary convex lens that is cut into discontinuous surfaces with constant curvature.Fresnel lens achieves the same optical effect by dividing the lens into a series of theoretically infinite concentric circles (i.e. Fresnel bands).So it looks like a circular pattern.

History has produced lighter and thinner lenses, with sharper edges, by mounting several separate sections to a frame.The center is a smoother projection, and each ring is actually a different prism, but at the expense of the quality of the image, which, on closer inspection, is made up of many tiny sheets.Fresnel lenses are often made of glass or plastic, ranging in size from large (old-fashioned lighthouses, to modern CNC machine tools (CNC) after the advent of most cases.They were thin and flat, and the advent of optical plastics made Fresnel lenses easy to make, about 3-5 millimeters thick.