Influence of light polarization state on the imaging quality of dark-field imaging system

2021 ◽  
Author(s):  
Dan Chen ◽  
Yuqin Wang ◽  
Rongzhu Zhang
Keyword(s):  
Intensity Distribution ◽  
Surface Defects ◽  
Imaging System ◽  
Detection System ◽  
Polarization State ◽  
Polarized Light ◽  
Dark Field ◽  
Light Polarization ◽  
Dark Field Imaging ◽  
Field Imaging

Abstract Annular linear polarized light is used as the illumination source of the reflective dark-field detecting system in this paper. According to the theories of the Bidirectional Reflectance Distribution Function (BRDF) and multi-beam interference, the influence of the light polarization state on the intensity distribution of the scattering light is analyzed in detail. For surface defects, a simulation model of dark-field imaging is established based on the Finite-Difference Time-Domain method (FDTD). Both the near-field and the far-field scattering intensity distribution caused by surface defects are calculated under different illumination conditions. The incidence angle and polarization state of illumination light are optimized. Simulation and experimental results show that the image quality will be minimally affected by the interference effect while P-polarized light illuminates with the incident angle of 45°. The higher measurement accuracy of the dark-field imaging detection system can be obtained when the optimized illumination scheme is used.

scholarly journals A New Stitching Method for Dark-Field Surface Defects Inspection Based on Simplified Target-Tracking and Path Correction

Sensors ◽  
2020 ◽  
Vol 20 (2) ◽  
pp. 448
Author(s):  
Chen ◽  
Li ◽  
Sui
Keyword(s):  
Target Tracking ◽  
Surface Defects ◽  
Imaging System ◽  
Dark Field ◽  
Dark Field Imaging ◽  
Fine Surface ◽  
Camera Perspective ◽  
Scanning Path ◽  
Field Imaging ◽  
Small Field Of View

A camera-based dark-field imaging system can effectively detect defects of microns on large optics by scanning and stitching sub-apertures with a small field of view. However, conventional stitching methods encounter problems of mismatches and location deviations, since few defects exist on the tested fine surface. In this paper, a highly efficient stitching method is proposed, based on a simplified target-tracking and adaptive scanning path correction. By increasing the number of sub-apertures and switching to camera perspective, the defects can be regarded as moving targets. A target-tracking procedure is firstly performed to obtain the marked targets. Then, the scanning path is corrected by minimizing the sum of deviations. The final stitching results are updated by re-using the target-tracking method. An experiment was carried out on an inspection of our specially designed testing sample. Subsequently, 118 defects were identified out of 120 truly existing defects, without stitching mismatches. The experiment results show that this method can help to reduce mismatches and location deviations of defects, and it was also effective in increasing the detectability for weak defects.

3d Reconstruction of Sub-Nm Beam Profiles in STEM

2001 ◽  
Vol 7 (S2) ◽  
pp. 344-345
Author(s):  
G. Möbus ◽  
R.E. Dunin-Borkowski ◽  
C.J.D. Hethėrington ◽  
J.L. Hutchison
Keyword(s):  
Electron Beam ◽  
Chemical Analysis ◽  
Energy Loss ◽  
Intensity Distribution ◽  
Dark Field ◽  
Beam Forming ◽  
Dark Field Imaging ◽  
Annular Dark Field ◽  
Electron Energy Loss ◽  
Field Imaging

Introduction:Atomically resolved chemical analysis using techniques such as electron energy loss spectroscopy and annular dark field imaging relies on the ability to form a well-characterised sub-nm electron beam in a FEGTEM/STEM [1-2]. to understand EELS+EDX-signal formation upon propagation of a sub-nm beam through materials we first have to assess precisely the beam intensity distribution in vacuum and find conditions for the best obtainable resolution.Experimental Details:Modern TEM/STEM instruments combine features of both imaging and scanning technology. The beam forming capability approaches closely that for dedicated STEMs, while CCD recording devices allow us to measure the beam profile by direct imaging at magnifications up to 1.5 M. The recording of a “z-section” series through the 3D intensity distribution of the cross-over can therefore be realised by recording of a “condenser focal series”.

scholarly journals Microfluidic Platform combined with a Dark Field Imaging System for Quantification of E. coli Contamination in Water

2021 ◽  
Author(s):  
Anna Malec ◽  
Christoph Haiden ◽  
Georgios Kokkinis ◽  
Ioanna Giouroudi
Keyword(s):  
Magnetic Particles ◽  
Imaging System ◽  
Optical Resolution ◽  
Dark Field ◽  
Small Sample ◽  
Resolution Limit ◽  
Buffer Solution ◽  
E Coli ◽  
Dark Field Imaging ◽  
Field Imaging

In this paper, we present a method for detecting and quantifying pathogens in water samples. The method proposes a portable dark field imaging and analysis system for quantifying E. coli concentrations in water after being labeled with magnetic particles. The system utilizes the tracking of moving micro/nano objects close to or below the optical resolution limit confined in small sample volumes (~ 10 µl). In particular, the system analyzes the effect of volumetric changes due to bacteria conjugation to magnetic microparticles (MP) on their Brownian motion while being suspended in liquid buffer solution. The method allows for a simple inexpensive implementation and the possibility to be used as point-of-need testing system. Indeed, a work-ing prototype is demonstrated with the capacity of quantifying E. coli colony forming units (CFU) at a range of 1x10³ - 6x10³ CFU/mL.

scholarly journals Nanometer precise red blood cell sizing using a cost-effective quantitative dark field imaging system

2020 ◽  
Vol 11 (10) ◽  
pp. 5950
Author(s):  
Xiaoya Chen ◽  
Peng Luo ◽  
Chuanzhen Hu ◽  
Shaojie Yan ◽  
Dapeng Lu ◽  
...  
Keyword(s):  
Blood Cell ◽  
Red Blood Cell ◽  
Imaging System ◽  
Cost Effective ◽  
Dark Field ◽  
Dark Field Imaging ◽  
Cell Sizing ◽  
Field Imaging

Optics, Optical Methods, and Microscopy

2021 ◽  
pp. 345-407
Author(s):  
Kannan M. Krishnan
Keyword(s):  
Optical Microscopy ◽  
Polarization State ◽  
Three Dimensional ◽  
Polarized Light ◽  
Dark Field ◽  
Optical Methods ◽  
Transverse Waves ◽  
Dark Field Imaging ◽  
Propagation Of Light ◽  
Scanning Optical Microscopy

Propagation of light is described as the simple harmonic motion of transverse waves. Combining waves that propagate on orthogonal planes give rise to linear, elliptical, or spherical polarization, depending on their amplitudes and phase differences. Classical experiments of Huygens and Young demonstrated the principle of optical interference and diffraction. Generalization of Fraunhofer diffraction to scattering by a three-dimensional arrangement of atoms in crystals forms the basis of diffraction methods. Fresnel diffraction finds application in the design of zone plates for X-ray microscopy. Optical microscopy, with resolution given by the Rayleigh criterion to be approximately half the wavelength, works best when tailored to the optimal characteristics of the human eye (λ = 550 nm). Lenses suffer from spherical and chromatic aberrations, and astigmatism. Optical microscopes operate in bright-field, oblique, and dark-field imaging conditions, produce interference contrast, and can image with polarized light. Variants include confocal scanning optical microscopy (CSOM). Metallography, widely used to characterize microstructures, requires polished or chemically etched surfaces to provide optimal contrast. Finally, the polarization state of light reflected from the surface of a specimen is utilized in ellipsometry to obtain details of the optical properties and thickness of thin film materials.

Dark field imaging system for size characterization of magnetic micromarkers

2017 ◽  
Author(s):  
A. Malec ◽  
C. Haiden ◽  
G. Kokkinis ◽  
F. Keplinger ◽  
I. Giouroudi
Keyword(s):  
Imaging System ◽  
Dark Field ◽  
Dark Field Imaging ◽  
Size Characterization ◽  
Field Imaging

A Microfluidic Chip and Dark-Field Imaging System for Size Measurement of Metal Wear Particles in Oil

2016 ◽  
Vol 16 (5) ◽  
pp. 1182-1189 ◽  
Author(s):  
Christoph Haiden ◽  
Thomas Wopelka ◽  
Martin Jech ◽  
Franz Keplinger ◽  
Michael J. Vellekoop
Keyword(s):  
Microfluidic Chip ◽  
Imaging System ◽  
Dark Field ◽  
Wear Particles ◽  
Size Measurement ◽  
Dark Field Imaging ◽  
Metal Wear ◽  
Field Imaging ◽  
Metal Wear Particles
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