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  2. Gravitational lensing formalism - Wikipedia

    en.wikipedia.org/wiki/Gravitational_lensing...

    Angles involved in a thin gravitational lens system. As shown in the diagram on the right, the difference between the unlensed angular position and the observed position is this deflection angle, reduced by a ratio of distances, described as the lens equation

  3. List of optics equations - Wikipedia

    en.wikipedia.org/wiki/List_of_optics_equations

    Visulization of flux through differential area and solid angle. As always ^ is the unit normal to the incident surface A, = ^, and ^ is a unit vector in the direction of incident flux on the area element, θ is the angle between them.

  4. Cardinal point (optics) - Wikipedia

    en.wikipedia.org/wiki/Cardinal_point_(optics)

    For a single lens surrounded by a medium of refractive index n = 1, the locations of the principal points H and H ′ with respect to the respective lens vertices are given by the formulas = ′ = (), where f is the focal length of the lens, d is its thickness, and r 1 and r 2 are the radii of curvature of its surfaces. Positive signs indicate ...

  5. Einstein radius - Wikipedia

    en.wikipedia.org/wiki/Einstein_radius

    For a source right behind the lens, θ S = 0, the lens equation for a point mass gives a characteristic value for θ 1 that is called the Einstein angle, denoted θ E. When θ E is expressed in radians, and the lensing source is sufficiently far away, the Einstein Radius, denoted R E, is given by =. [2]

  6. Conjugate focal plane - Wikipedia

    en.wikipedia.org/wiki/Conjugate_focal_plane

    For a thin lens or a curved mirror, + =, where u is the distance from the object to the center of the lens or mirror, v is the distance from the lens or mirror to the image, and f is the focal length of the lens or mirror.

  7. Thin lens - Wikipedia

    en.wikipedia.org/wiki/Thin_lens

    A lens may be considered a thin lens if its thickness is much less than the radii of curvature of its surfaces (d ≪ | R 1 | and d ≪ | R 2 |).. In optics, a thin lens is a lens with a thickness (distance along the optical axis between the two surfaces of the lens) that is negligible compared to the radii of curvature of the lens surfaces.

  8. Numerical aperture - Wikipedia

    en.wikipedia.org/wiki/Numerical_aperture

    In microscopy, NA is important because it indicates the resolving power of a lens. The size of the finest detail that can be resolved (the resolution) is proportional to ⁠ λ / 2NA ⁠, where λ is the wavelength of the light. A lens with a larger numerical aperture will be able to visualize finer details than a lens with a smaller numerical ...

  9. Virbhadra–Ellis lens equation - Wikipedia

    en.wikipedia.org/wiki/Virbhadra–Ellis_lens...

    The Virbhadra-Ellis lens equation [1] in astronomy and mathematics relates to the angular positions of an unlensed source (), the image (), the Einstein bending angle of light (^), and the angular diameter lens-source () and observer-source () distances.