aberration

(noun)

The convergence to different foci, by a lens or mirror, of rays of light emanating from one and the same point, or the deviation of such rays from a single focus; a defect in a focusing mechanism that prevents the intended focal point.

Related Terms

Examples of aberration in the following topics:

  • Aberrations

    • A chromatic aberration, also called achromatism or chromatic distortion, is a distortion of colors .
    • This aberration happens when the lens fails to focus all the colors on the same convergence point .
    • A comatic aberration, or coma, occurs when the object is off-center.
    • These aberrations can cause objects to appear pear-shaped.
    • Spherical aberrations are a form of aberration where rays converging from the outer edges of a lens converge to a focus closer to the lens, and rays closer to the axis focus further.

  • Combinations of Lenses

    • The use of multiple elements allows for the correction of more optical aberrations, such as the chromatic aberration caused by the wavelength-dependent index of refraction in glass, than is possible using a single lens.
    • In many cases these aberrations can be compensated for to a great extent by using a combination of simple lenses with complementary aberrations.
    • An achromatic lens or achromat is a lens that is designed to limit the effects of chromatic and spherical aberration.
    • The lens elements are mounted next to each other, often cemented together, and shaped so that the chromatic aberration of one is counterbalanced by that of the other.
    • (a) Chromatic aberration is caused by the dependence of a lens's index of refraction on color (wavelength).

  • The Telescope

    • The potential advantages of using mirrors instead of lenses were a reduction in spherical aberrations and the elimination of chromatic aberrations.
    • With the invention of achromatic lenses in 1733, color aberrations were partially corrected, and shorter, more functional refracting telescopes could be constructed.

  • Adding velocities

    • This is the aberration equation.

  • Air Wedge

    • To minimize image aberrations of the resulting fringes, the angle plane of the glass wedges has to be placed orthogonal to the angle plane of the air-wedge.

  • Cancer and Transcriptional Control

    • This could also lead to the increased transcription and aberrant gene expression that is seen in cancer cells.

  • The Compound Microscope

    • The advantages of these microscopes, due to the multiple lenses, are the reduced chromatic aberrations and exchangeable objective lenses to adjust magnification.

  • Termination of the Signal Cascade

    • The aberrant signaling often seen in tumor cells is proof that the termination of a signal at the appropriate time can be just as important as the initiation of a signal.

  • Adhesions

    • Adhesions are aberrant fibrous bands that form between tissues often following surgery or injury and are similar to internal scarring.

  • Cell-Mediated Autoimmune Reactions

    • This fact gave rise to the idea that spontaneous autoimmunity may result when the binding of antibody to certain antigens leads to aberrant signals being fed back to parent B cells through membrane bound ligands.
    • More indirect aberrant activation of B cells can also be envisaged with autoantibodies to acetyl choline receptor (on thymic myoid cells) and hormone binding proteins.