magnifying glass

A pen seen through a magnifying glass Jim Hutton as detective Ellery Queen, posing with a magnifying glass A magnifying glass is a convex lens—usually mounted in a frame with a handle—that is used to produce a magnified image of an object. A magnifying glass can also be used to focus light, such as to concentrate the Sun's radiation to create a hot spot at the focus for fire starting.

Evidence of magnifying glasses exists from antiquity. The magnifying glass is an icon of detective fiction, particularly that of Sherlock Holmes.