Magnifying glass

A magnifying glass is a convex lens that is used to produce a magnified image of an object. The lens is usually mounted in a frame with a handle. Beyond its primary function of magnification, this simple yet ingenious tool serves a variety of purposes. It can be employed to focus sunlight, harnessing the Sun's rays to create a concentrated hot spot at the lens's focus, which is often used for starting fires.

In another innovative form, the magnifying glass can manifest as a sheet magnifier, employing numerous slender, concentric, ring-shaped lenses. These are collectively known as a Fresnel lens, which, despite being significantly thinner, operates effectively as a single lens. This particular design finds its utility in applications such as screen magnifiers for TVs, offering a lightweight and efficient solution for enlarging visuals.

A plastic Fresnel lens sold as a TV-screen magnifier

The cultural impact of the magnifying glass extends far into the realms of literature and pop culture, symbolizing the pursuit of truth and the uncovering of secrets. It is famously associated with the investigative work of fictional detectives, with Sherlock Holmes being the most iconic figure to wield it, cementing its status as an emblem of detective fiction. Through its various forms and functions, the magnifying glass remains a tool of both practical utility and significant symbolic value.