Reduction in Edge-Ringing in Aberrated Images of Coherent Edge Objects by Multishaded Aperture

Mekala, Venkanna; Dasari, Karuna Sagar

doi:10.1155/2014/963980

Cited by 5 publications

(2 citation statements)

References 3 publications

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“…In earlier studies, specimens with thin steps were used; thus, beam shading was negligible and the step responses agreed with the direct convolution results [12,13]. In these cases, the step edge positions in coherent and incoherent imaging could be defined as the lateral positions at which 1/4 or 1/2, respectively, of the amplitudes of the steadystate light intensities occurred [14][15][16]. Metrology on deep grooves is more complicated since beam cutting is no longer negligible.…”

Section: Introductionmentioning

confidence: 66%

Decoupling criterion based on limited energy loss condition for groove measurement using optical scanning microscopes

Liu

et al. 2016

Meas. Sci. Technol.

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In confocal metrology, the lateral and axial responses are coupled in narrow regions near groove edges. This coupling results in an area with an uncertain profile, particularly for measurements of tight structures or deep grooves. In this paper, to delineate the area with measurement accuracy loss, an analytical model depicting the coupling relationships between the groove depth, the coupled portions and the NA of the objective used is introduced. Based on this model, the limited energy lost (LEL) decoupling criterion is presented that can enable users to choose suitable numerical apertures before performing measurements, predict the extents of the areas with measurement accuracy loss, and identify readout areas that yield accurate height measurements. The theory was verified by using confocal microscopes and is also applicable to far-field optical scanning metrology.

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Section: Introductionmentioning

confidence: 66%

Decoupling criterion based on limited energy loss condition for groove measurement using optical scanning microscopes

Liu

et al. 2016

Meas. Sci. Technol.

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“…However, the authors also point out that the method does not consider the occlusion effect and the reflection from the edge, and also assumes that the images of the straight edges of the two half-planes do not affect each other, so this method may not be effective. The subsequent studies on the analysis of edge imaging of a fibre-optic confocal microscope [9] and on the analysis of the influence of aberration on edge imaging [10][11][12][13] also ignore the influence of the occlusion effect on edge imaging and the mutual influence of upper and lower surface imaging of steps. In a previous work, we considered the occlusion effect caused by height introduction into 3D microscopy imaging, and built an imaging model that takes into account the joint effect of occlusion and blurred light field to calculate the intensity response of step or groove edges to determine the edge position [14].…”

Section: Introductionmentioning

confidence: 99%

Width determination for deep grooves in dark-field confocal microscopy measurements

Liu

Jiang²,

You³

et al. 2022

Surf. Topogr.: Metrol. Prop.

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Dark-field confocal microscopy is effectively used for 3D surface and subsurface measurement due to its ability to suppress strong reflected signals from measured surfaces. However, in 3D characterization of microstructure morphology, edge imaging degrades due to the influence of microstructure edge occlusion, so the microstructure edge position cannot be accurately determined. This limitation is serious when dark-field confocal microscopy is used for width determination of deep grooves/step samples. In this paper, a method for determining the width for deep grooves in dark-field confocal microscopy is proposed to determine the edge position with the groove's lower surface in focus. Experimental results show the width determination method has higher precision compared to conventional 1/4 edge determination, reducing the standard deviation by 57.58 %.

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Edge imaging characteristics of aberrated coherent optical systems by edge masking of circular apertures

Venkanna¹,

Sagar

2022

Computer Optics

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In this paper, attempts have been made to study the joint effects of apodization and aperture masking on the diffraction images of coherently illuminated straight edge. The Edge-Ringing, Edge-Shift and Edge-Eradient of the edge images have been evaluated for different values of apo-dization using edge masking of circular apertures. We have considered rotationally symmetric, ab-errated coherent optical system. These investigations have lead to the use of certain pupil functions in conjunction with optimal apodizers to assess the quality of edge images. Any obstruction placed in the light path of an optical system prevents waves from a portion of the wavefront in reaching the focal zone. This results in the change in the light flux at every point of the diffraction pattern. This is in turn, depends on the shape and size of the obstruction.

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Reduction in Edge-Ringing in Aberrated Images of Coherent Edge Objects by Multishaded Aperture

Cited by 5 publications

References 3 publications

Decoupling criterion based on limited energy loss condition for groove measurement using optical scanning microscopes

Decoupling criterion based on limited energy loss condition for groove measurement using optical scanning microscopes

Width determination for deep grooves in dark-field confocal microscopy measurements

Edge imaging characteristics of aberrated coherent optical systems by edge masking of circular apertures

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