Evaluation of both image resolution and contrast-to-noise ratio in scanning electron microscopy

Abstract

The contrast-to-gradient (CG) resolution has been defined as a weighted harmonic mean of the local resolution, i.e. the length defining the object's local fine structure at each pixel position. The newly defined resolution Res is defined as 2 sigma/ sqrt 2, where 2 sigma is a sharpness factor of the image pattern obtained by the conversion 2 sigma = ARCG + B using default constants A and B. In the present study, we have extended the algorithm to change the constants from default values to calibrated ones using standard images that are same in both pattern and contrast-to-noise ratio (CNR) as the original SEM image to be evaluated. The calibrated image resolution with a weak noise dependency is evaluated with the CNR as a given parameter.

Comparison of secondary electron emission in helium ion microscope with gallium ion and electron microscopes

“…Furthermore, it is an important measure of microscopy performances to evaluate the image resolution, such as sharpness, quantitatively; e.g. Fourier transform (FT) method, autocorrelation function (ACF) method and constant-to-gradient (CG) methods are conventionally used [14]. Therefore, more detailed discussions are necessary along with the comparison with the experimental image observations.…”

A carbon nanotube tape for serial-section electron microscopy of brain ultrastructure

“…6c, f ). We found better values in both the Michelson contrast calculated at half width of the histogram and contrast-to-noise ratio (CNR) 44 , 45 for images captured with 3–4 keV using the BSD, and with 1.5–2 keV using the In-lens SE (Fig. 6g , Supplementary Table 3 ).…”

“…For a calculation of contrast-to-noise (CNR) 44 , 45 , the background noise value (σvb 2 ) is used as a noise value, then the CNR can be obtained: …”

A Monte Carlo simulation study on the image resolution in scanning electron microscopy

“…Therefore, an even better nominal resolution would be achieved by selecting the gap width as narrow as 0.3-0.4 nm for a 0.2-nm true gap separation. Besides the gap method, we also use the C-G method [8] to evaluate the image (Fig. 2(a)); a resolution of ∼0.25 nm is obtained.…”

“…Furthermore, various attempts [5] have been made at developing a suitable method for resolution measurement, such as the gap method, [6] the derivative method, the Fourier transform (FT) method, [7] the contrast-to-gradient (C-G) method, [8] and the correlation method. [9] The evaluation of the accuracy of these methods requires serial test SEM images [6,10] with varied parameters, such as structured grains and background, edge effect, blurring, vibration, and noise.…”