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  2. 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 ...

  3. Near-field scanning optical microscope - Wikipedia

    en.wikipedia.org/wiki/Near-field_scanning...

    Here, λ 0 is the wavelength in vacuum; NA is the numerical aperture for the optical component (maximum 1.3–1.4 for modern objectives with a very high magnification factor). Thus, the resolution limit is usually around λ 0 /2 for conventional optical microscopy.

  4. Gaussian beam - Wikipedia

    en.wikipedia.org/wiki/Gaussian_beam

    The numerical aperture of a Gaussian beam is defined to be NA = n sin θ, where n is the index of refraction of the medium through which the beam propagates. This means that the Rayleigh range is related to the numerical aperture by z R = n w 0 N A . {\displaystyle z_{\mathrm {R} }={\frac {nw_{0}}{\mathrm {NA} }}.}

  5. Diffraction-limited system - Wikipedia

    en.wikipedia.org/wiki/Diffraction-limited_system

    Memorial in Jena, Germany to Ernst Karl Abbe, who approximated the diffraction limit of a microscope as = ⁡, where d is the resolvable feature size, λ is the wavelength of light, n is the index of refraction of the medium being imaged in, and θ (depicted as α in the inscription) is the half-angle subtended by the optical objective lens (representing the numerical aperture).

  6. f-number - Wikipedia

    en.wikipedia.org/wiki/F-number

    where N is the uncorrected f-number, NA i is the image-space numerical aperture of the lens, | | is the absolute value of the lens's magnification for an object a particular distance away, and P is the pupil magnification. Since the pupil magnification is seldom known it is often assumed to be 1, which is the correct value for all symmetric lenses.

  7. Normalized frequency (fiber optics) - Wikipedia

    en.wikipedia.org/wiki/Normalized_frequency...

    In an optical fiber, the normalized frequency, V (also called the V number), is given by = =, where a is the core radius, λ is the wavelength in vacuum, n 1 is the maximum refractive index of the core, n 2 is the refractive index of the homogeneous cladding, and applying the usual definition of the numerical aperture NA.

  8. Point spread function - Wikipedia

    en.wikipedia.org/wiki/Point_spread_function

    When the peaks are as close as ~ 1 wavelength/NA, they are effectively merged. The FWHM is ~ 0.6 wavelength/NA at this point. The PSF is also a fundamental limit to the conventional focused imaging of a hole, [9] with the minimum printed size being in the range of 0.6-0.7 wavelength/NA, with NA being the numerical aperture of the imaging system.

  9. Angular resolution - Wikipedia

    en.wikipedia.org/wiki/Angular_resolution

    Here NA is the numerical aperture, is half the included angle of the lens, which depends on the diameter of the lens and its focal length, is the refractive index of the medium between the lens and the specimen, and is the wavelength of light illuminating or emanating from (in the case of fluorescence microscopy) the sample.