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PSF Lab is a software program that allows the calculation of the illumination point spread function (PSF) of a confocal microscope under various imaging conditions. The calculation of the electric field vectors is based on a rigorous, vectorial model that takes polarization effects in the near-focus region and high numerical aperture microscope objectives into account.
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 ...
As an example, the figure on the right shows the 3D point-spread function in object space of a wide-field microscope (a) alongside that of a confocal microscope (c). Although the same microscope objective with a numerical aperture of 1.49 is used, it is clear that the confocal point spread function is more compact both in the lateral dimensions ...
Köhler illumination is a method of specimen illumination used for transmitted and reflected light (trans- and epi-illuminated) optical microscopy.Köhler illumination acts to generate an even illumination of the sample and ensures that an image of the illumination source (for example a halogen lamp filament) is not visible in the resulting image.
The aperture function cuts off beams scattered above a certain critical angle (given by the objective pole piece for ex), thus effectively limiting the attainable resolution. However it is the envelope function E(u) which usually dampens the signal of beams scattered at high angles, and imposes a maximum to the transmitted spatial frequency ...
Its defining characteristic is translational invariance, which means that the interference patterns are generated by one constant function (e.g. a field of illumination or an aperture stop) moving laterally by a known amount with respect to another constant function (the specimen itself or a wave field).
The specifications for a given lens typically include the maximum and minimum aperture (opening) sizes, for example, f /0.95 – f /22. In this case, f /0.95 is currently the maximum aperture (the widest opening on a full-frame format for practical use [8]), and f /22 is the minimum aperture (the smallest opening). The maximum aperture tends to ...
where α 0 is half the angle spanned by the objective lens seen from the sample, and n is the refractive index of the medium between the lens and specimen (≈1 for air). State-of-the-art objectives can have numerical apertures of up to 0.95. Because sin α 0 ≤ 1, the numerical aperture can never be greater than unity for an objective lens in ...