A loupe is one type of handheld magnifying tool. They are typically small and generally rely only on conventional optics to magnify an image. The simplest consist of little more than a single lens used to magnify an image. More intricate versions combine several lenses and may include markings, lights, or other features designed to make them more useful for members of a particular profession. Loupes are commonly used by professionals, including geologists, typographers, and many medical professionals who must occasionally examine small items in detail.
Typical loupes consist of one or more lenses designed to allow the magnification of a small object. The lenses used in these devices generally range from 2x to 30x power. As lenses become more powerful, focal distances decrease. This means that very powerful lenses will only focus properly on items that are extremely close to them. This sort of loupe can be useful, especially for jewelers or others who need to be able to observe objects in exquisite detail, but is of little use in less-than-optimal lighting conditions.
Most of these devices are designed to fold into a case, usually made of metal. This makes them durable enough to carry safely into the field and protects the lenses against scratches and other incidental hazards. Many modern versions, especially high-power examples, include a built-in light source. Adding a light to a standard loupe makes more powerful magnifiers easier to use, as it guarantees adequate illumination of the object being examined.
Geologists and jewelers both often make use of these devices. A loupe can be carried in a pocket and used to examine gemstones or mounted to a pair of glasses on a flip-down frame. The geologist’s hand lens is invaluable in identifying finds.
Specialized models of loupe are available for professionals with very specific magnifying needs. Some types of loupe, for instance, are designed for use by typographers. These include a printed scale on the base of the device, and allow a user looking through the focusing lens to effectively determine the type size of printed text that is examined through the loupe.
Many medical professionals use this type of magnifying glass as well. A dentist or a surgeon can use such a lens to examine specific physiological features in greater detail. These devices typically come in pairs and are generally fixed and mounted to a pair of glasses or other support structure, so that a doctor or dentist has both binocular vision and two free hands. These loupes are almost always lighted and may include more advanced electronics such as built-in cameras.