image distance

(noun)

The distance of the image from the center of the lens.

Related Terms

Examples of image distance in the following topics:

  • The Thin Lens Equation and Magnification

    • The thin lens equation relates the object distance do, image distance di, and focal length f.
    • Several important distances appear in .
    • We define do as the object distance—the distance of an object from the center of a lens.
    • Image distance diis defined as the distance of the image from the center of a lens.
    • Shows how to use the thin lens equation to calculate the image distance, image height and image orientation for convex lenses when the object distance is greater the the focal length (f).

  • Image Reflection by a Plane Mirror

    • A "real" image occurs when light rays actually intersect at the image, and become inverted, or turned upside down.
    • A "virtual" image occurs when light rays do not actually meet at the image.
    • You are fooled into seeing an image!
    • In flat, or plane mirrors, the image is a virtual image, and is the same distance behind the mirror as the object is in front of the mirror.
    • Draw the image of the object, by using the principle that the image is placed at the same distance behind the mirror that the object is in front of the mirror.

  • Perceiving Depth, Distance, and Size

    • Perception of depth, size, and distance is achieved using both monocular and binocular cues.
    • How do we perceive images?
    • Are the images we see directly mapped onto our brain like a projector?
    • Size and distance of objects are also determined in relation to each other.
    • An example of this can be seen in the image of train tracks disappearing into the distance.

  • Nearsightedness, Farsidedness, and Vision Correction

    • In order for the human eye to see clearly, the image needs to be formed directly on the retina; if it is not, the image is blurry.
    • When the image finally reaches the retena, it is inverted, but the brain will correct this .
    • For the vision to be clear, the image has to be formed directly on the retina.
    • The focus needs to be changed, much like a camera, depending on the distance and size of the object.
    • The distance to the object is drawn smaller than scale.

  • The Distance Formula and Midpoints of Segments

    • In analytic geometry, the distance between two points of the $xy$-plane can be found using the distance formula.  
    • The distance can be from two points on a line or from two points on a line segment.  
    • The distance between points $(x_{1},y_{1})$ and $(x_{2},y_{2})$ is given by the formula:
    • This formula is easily derived by constructing a right triangle with the hypotenuse connecting the two points ($c$) and two legs drawn from the each of the two points to intersect each other ($a$ and $b$), (see image below) and applying the Pythagorean theorem.
    • The image below names the two points, with the distance between them as the variable, $d$.  

  • Image Formation by Spherical Mirrors: Reflection and Sign Conventions

    • This image that appears to be behind the mirror is called the image.
    • A real image occurs when light rays actually intersect at the image, and is inverted, or upside down.
    • A virtual image occurs when light rays do not actually meet at the image.
    • The distance to the focal point from the mirror is called the focal length.
    • The focal point is the same distance from the mirror as in a concave mirror.

  • Isotopes in Medicine

    • These images are based on cellular function and physiology, rather than on physical changes in the tissue anatomy.
    • In nuclear medical imaging, radiopharmaceuticals are taken internally, either intravenously or orally.
    • Nuclear medicine differs from most other imaging in that diagnostic tests primarily show the physiological function of the system being investigated, as opposed to traditional anatomic imaging, such as CT or MRI.
    • The radiopharmaceuticals used in nuclear medicine therapy emit ionizing radiation that travels only a short distance.
    • These images are scans used in the evaluation of thyroid cancer using the isotope iodine-123.

  • Applications: Ultrasound, Sonar, and Medical Imaging

    • Controlled reflection of such waves allows images to be received.
    • The most common use of ultrasound, creating images, has industrial and medical applications.
    • The reflected rays are detected and used to construct an image of the object.
    • Because the speed of sound is known and the time lapse between sending and receiving the sound can be measured, the distance from the ship to the bottom of the ocean can be determined.
    • Because the speed of sound is known and the time lapse between sending and receiving the sound can be measured, the distance from the ship to the bottom of the ocean can be determined.

  • The Compound Microscope

    • A compound microscope uses multiple lenses to magnify an image for an observer.
    • The distance between the object and the objective lens is slightly longer than the focal length, f0.
    • The distance between the objective lens and the ocular lens is slightly shorter than the focal length of the ocular lens, fe.
    • This causes the ocular lens to act as a magnifying glass to the first image and makes it even larger.
    • This diagram shows the setup of mirrors that allow for the magnification of images.

  • Emission Topography

    • Positron emission tomography is a nuclear medical imaging technique that produces a three-dimensional image of processes in the body.
    • Positron emission tomography (PET) is a nuclear medical imaging technique that produces a three-dimensional image or picture of functional processes in the body.
    • The emitted positron travels in tissue for a short distance (typically less than 1 mm, but dependent on the isotope), during which time it loses kinetic energy, until it decelerates to a point where it can interact with an electron.
    • Because PET imaging is most useful in combination with anatomical imaging, such as CT, modern PET scanners are now available with integrated high-end multi-detector-row CT scanners .
    • Because the two scans can be performed in immediate sequence during the same session, with the patient not changing position between the two types of scans, the two sets of images are more-precisely registered, so that areas of abnormality on the PET imaging can be more perfectly correlated with anatomy on the CT images.