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Due to Snell's law, the numerical aperture remains the same: NA = n 1 sin θ 1 = n 2 sin θ 2. In optics, the numerical aperture (NA) of an optical system is a dimensionless number that characterizes the range of angles over which the system can accept or emit light.
The optical configuration for Fourier ptychography. Fourier ptychography is a computational imaging technique based on optical microscopy that consists in the synthesis of a wider numerical aperture from a set of full-field images acquired at various coherent illumination angles, [1] resulting in increased resolution compared to a conventional microscope.
The three-dimensional point spread functions (a,c) and corresponding modulation transfer functions (b,d) of a wide-field microscope (a,b) and confocal microscope (c,d). In both cases the numerical aperture of the objective is 1.49 and the refractive index of the medium 1.52.
Digital holography offers a means of measuring optical phase data and typically delivers three-dimensional surface or optical thickness images. Several recording and processing schemes have been developed to assess optical wave characteristics such as amplitude, phase, and polarization state, which make digital holography a very powerful method ...
It works because numerical aperture is a function of the maximum angle of light that can enter the lens and the refractive index of the medium through which the light passes. When water is employed as the medium, it greatly increases numerical aperture, since it has a refractive index of 1.44 at 193 nm, while air has an index of 1.0003.
A real Airy disk created by passing a red laser beam through a 90-micrometre pinhole aperture with 27 orders of diffraction Airy disk captured by 2000 mm camera lens at f/25 aperture. Image size: 1×1 mm. In optics, the Airy disk (or Airy disc) and Airy pattern are descriptions of the best-focused spot of light that a perfect lens with a ...
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. [17]
The f-number N is given by: = where f is the focal length, and D is the diameter of the entrance pupil (effective aperture).It is customary to write f-numbers preceded by "f /", which forms a mathematical expression of the entrance pupil's diameter in terms of f and N. [1]