Focal length
Focal Length
Focal length (pronounced: FOH-kul LENGKTH) is a term used in optics to describe the distance (in millimeters) between the lens and the image sensor when the subject is in focus. It is not a medical term per se, but it is often used in medical contexts, particularly in ophthalmology and medical imaging.
Etymology
The term "focal length" originates from the Latin word "focus", meaning "hearth, fireplace", and the Old English "lengthu", meaning "length". In the context of optics, it refers to the point at which light rays originating from a point on the object converge.
Related Terms
- Optics: The scientific study of sight and the behavior of light, or the properties of transmission and deflection of other forms of radiation.
- Lens: A piece of glass or other transparent substance with curved sides for concentrating or disseminating light rays.
- Ophthalmology: The branch of medicine that deals with the diagnosis and treatment of disorders of the eye.
- Medical Imaging: The technique and process of creating visual representations of the interior of a body for clinical analysis and medical intervention.
Usage in Medical Context
In ophthalmology, the focal length of the eye is considered, which is essentially the distance from the cornea to the retina. This measurement is important in determining the refractive error of the eye and prescribing corrective lenses. In medical imaging, the focal length of the lens used in the imaging device can affect the scale and detail of the image produced.
External links
- Medical encyclopedia article on Focal length
- Wikipedia's article - Focal length
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