A hyper-resolving polynomial aperture and its application in microscopy (original) (raw)
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Improvement of point spread function (PSF) using linear- quadratic aperture
Optik, 2017
Highlights This study is made looking forward to get further improvement in resolution of conventional and confocal microscopes. The described models of apertures are selected in order to get better PSF and consequently better resolution. A combination from modulated linear and quadratic distributions inside the aperture allows getting better resolution than the ordinary circular aperture. The resolution of a hyper-resolving aperture in the form of three different concentric layers is investigated. This new aperture has a successive quadratic, linear, and constant layers from the center. The central quadratic distributed segment from the aperture is selected to attenuate the low spatial frequencies. Another model of hyper-resolving aperture in the form of four concentric layers is investigated. In this aperture, from the center, a dark central disk followed by a higher order, 6 , distribution, the next is linear, and the last has constant layer. In this case, the spatial frequency attenuation is realized by the central dark disk followed by the 6 distribution. The point spread function (PSF) of the described two apertures is computed and compared with the corresponding annular and circular apertures. In addition, the coherent transfer function of the confocal microscope computed using the hyper-resolving apertures.
The Image of a Single Point in Microscopes of Large Numerical Aperture
Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 1982
The image of a single small hole in an opaque screen in a microscope of large numerical aperture is calculated. Both conventional microscopes and scanning optical microscopes are considered, the general trend being that the central peak is broadened, the outer rings strengthened and the minima made shallower as the numerical aperture is increased. In the conventional microscope the image is no longer independent of the illumination, as it is for paraxial theory.
Optimization of axial resolution in a confocal microscope with D-shaped apertures
Applied Optics, 2009
We show theoretically that the axial resolution is improved when two centrosymmetric D-shaped apertures are combined in a confocal microscope with a finite-sized pinhole. The optimum width of a divider that separates the D-shaped apertures to give the maximum axial resolution for a given pinhole size is investigated, and the magnitude of the signal level is explored.
A Study on Misaligned Modulated Apertures in Confocal Scanning Laser Microscope (CSLM)
2019
The famous work on the PSF is made by Sheppard et. al. [1-12] using annular and Gaussian apertures. Improvement of axial resolution in confocal microscopy using annular pupil is investigated in [9].Practical limits of resolution in confocal and nonlinear microscopy is presented in [11]. The effect of numerical aperture on interference fringe spacing is shown in [13]. Linear, quadratic, B/W concentric annuli, and graded index apertures is suggested by Hamed et. al. [14-20]. They computed the PSF considering the above modulated apertures giving lateral resolution improvement. Image analysis of modified Hamming aperture and an application on confocal microscopy and holography is given in [20]. Modulatedalignment dual-axis (MAD) confocal microscopy for deep optical sectioning in tissues is presented in [21]. While an image scanning microscopy with a quadrant detector is recently investigated [22].
Two point resolution of annular apertures
Several criteria of resolution, e.g. Rayleigh Criterion, Sparrow Criterion etc. are used for assessment of two point resolution of unobscured imaging systems. The choice of particular criterion is usually dictated by the threshold contrast sensitivity of the detector used for the purpose. Annular apertures have a narrower central lobe in the point spread function and therefore they are expected to provide improved two point resolution characteristics compared to their unobscured counterparts. This paper reports some results of our search on the interrelationship between the dip in central intensity, degree of central obscuration and the least resolvable distance. Besides illustrative graphical results, some closed form analytical formulae are presented for ready evaluation of this relationship in practical problems.
Scientific Reports, 2017
The limits of conventional light microscopy (“Abbe-Limit“) depend critically on the numerical aperture (NA) of the objective lens. Imaging at large working distances or a large field-of-view typically requires low NA objectives, thereby reducing the optical resolution to the multi micrometer range. Based on numerical simulations of the intensity field distribution, we present an illumination concept for a super-resolution microscope which allows a three dimensional (3D) optical resolution around 150 nm for working distances up to the centimeter regime. In principle, the system allows great flexibility, because the illumination concept can be used to approximate the point-spread-function of conventional microscope optics, with the additional benefit of a customizable pupil function. Compared with the Abbe-limit using an objective lens with such a large working distance, a volume resolution enhancement potential in the order of 104 is estimated.
Imaging by a High Aperture Optical System
Journal of Modern Optics, 1993
Three-dimensional imaging in telecentric systems of non-unity magnification is considered using a scalar approximation . It is found that the imaging performance can be very different according to whether the image is formed directly in the image space or by scanning in the object space. It is shown that this result does not violate the principle of reciprocity. The point spread function is investigated for systems obeying, amongst others, either the sine or Herschel conditions. The results have great importance for scanning systems, in particular confocal microscopes, and explain some anomalies in the literature. A clarification of the principle of equivalence is given .
Pramana, 2006
In this paper, a novel aperture based on Tolardo concept composed of a central clear disc surrounded by a series of black and white (B/W) concentric annuli of equal transmittance is presented. Different apodized apertures of different number of B/W annuli are suggested in order to improve further the three-dimensional resolving power of confocal imaging systems. Both the axial and lateral point spread functions (PSF) and the corresponding irradiances are computed in both cases of conventional and confocal scanning microscopes for the above-mentioned amplitude filters. These results of axial and lateral irradiances are graphically represented by constructing a computer program using MATLAB. The obtained results are compared with that obtained in case of circular, annular, and Martinez-Corral apodized aperture.