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  2. Astigmatism (optical systems) - Wikipedia

    en.wikipedia.org/wiki/Astigmatism_(optical_systems)

    The second plane used in the analysis is the sagittal plane, defined as the plane orthogonal to the tangential plane and containing the chief ray before refraction (so along the original chief ray direction). This plane intersects the optical axis at the entrance pupil of the optical system.

  3. Optical flat - Wikipedia

    en.wikipedia.org/wiki/Optical_flat

    The third method involves moving the eye in relation to the flat. When moving the eye from a zero-degree angle of incidence to an oblique angle, the fringes will appear to move. If the testing surface is concave, the fringes will appear to move toward the center. If the surface is convex, the fringes will move away from the center.

  4. Listing's law - Wikipedia

    en.wikipedia.org/wiki/Listing's_law

    Listing's law, named after German mathematician Johann Benedict Listing (1808–1882), describes the three-dimensional orientation of the eye and its axes of rotation. Listing's law has been shown to hold when the head is stationary and upright and gaze is directed toward far targets, i.e., when the eyes are either fixating, making saccades, or pursuing moving visual targets.

  5. Slip (materials science) - Wikipedia

    en.wikipedia.org/wiki/Slip_(materials_science)

    Slip systems in zirconium alloys. 𝒃 and 𝒏 are the slip direction and plane, respectively, and 𝝎 is the rotation axis calculated in the present work, orthogonal to both the slip plane normal and slip direction. The crystal direction of the rotation axis vectors is labelled on the IPF colour key.

  6. Pupil function - Wikipedia

    en.wikipedia.org/wiki/Pupil_function

    The pupil function or aperture function describes how a light wave is affected upon transmission through an optical imaging system such as a camera, microscope, or the human eye. More specifically, it is a complex function of the position in the pupil [ 1 ] or aperture (often an iris ) that indicates the relative change in amplitude and phase ...

  7. Schmid's law - Wikipedia

    en.wikipedia.org/wiki/Schmid's_Law

    Schmid's Law states that the critically resolved shear stress (τ) is equal to the stress applied to the material (σ) multiplied by the cosine of the angle with the vector normal to the glide plane (φ) and the cosine of the angle with the glide direction (λ). Which can be expressed as: [2] =

  8. Visual angle - Wikipedia

    en.wikipedia.org/wiki/Visual_angle

    The diagram on the right shows an observer's eye looking at a frontal extent (the vertical arrow) that has a linear size , located in the distance from point . For present purposes, point O {\displaystyle O} can represent the eye's nodal points at about the center of the lens, and also represent the center of the eye's entrance pupil that is ...

  9. Petzval field curvature - Wikipedia

    en.wikipedia.org/wiki/Petzval_field_curvature

    Field curvature: the image "plane" (the arc) deviates from a flat surface (the vertical line). Petzval field curvature, named for Joseph Petzval, [1] describes the optical aberration in which a flat object normal to the optical axis (or a non-flat object past the hyperfocal distance) cannot be brought properly into focus on a flat image plane.