A Novel Digital Measurement Technique For The Signal-To-Noise Ratio Of Image Intensifier Tubes

1987 ◽  
Author(s):  
A. G. Du Toit ◽  
M. F. Calitz ◽  
C. F. Van Huyssteen
Keyword(s):  
Measurement Technique ◽  
Signal To Noise Ratio ◽  
Image Intensifier ◽  
Digital Measurement ◽  
Signal To Noise ◽  
Noise Ratio

Compensating for the Phosphorescent Persistence in Intensified Cameras for Micro-PIV

2008 ◽  
Author(s):  
Adric Eckstein ◽  
Pavlos Vlachos
Keyword(s):  
Signal To Noise Ratio ◽  
Image Intensifier ◽  
Ccd Camera ◽  
Attractive Alternative ◽  
Cmos Camera ◽  
Signal To Noise ◽  
Ccd Cameras ◽  
Micro Piv ◽  
Noise Ratio ◽  
Cooled Ccd

Micro-PIV experiments rely upon the use of a microscope to achieve the higher spatial resolution. However, several optical limitations are introduced at these scales [1–3]. In addition, due to the low illumination levels, micro-PIV experiments require the use of either a cooled CCD camera or an image intensifier to provide increased signal-to-noise ratio. Although CCD cameras offer superior sensitivity and signal to noise ratio, intensified CMOS cameras offer an attractive alternative for performing high frequency measurements. However, intensified cameras are known to introduce artifacts such as added background noise. This study examines these issues and the feasibility of employing such technologies for microPIV through the use of the IDT-X5 intensified CMOS camera, capable of 500 Hz at a resolution of 2352×1728 pixels, with pulse separations as low as 2μs.

scholarly journals A SIGNAL-TO-NOISE RATIO MEASUREMENT TECHNIQUE BASED ON THE PROCESS HISTOGRAM

1991 ◽  
Vol 11 (1) ◽  
pp. 43-47
Author(s):  
M.A. Korol ◽  
I.G. Kudintseva ◽  
A.P. Nickolaenko ◽  
L.M. Rabinowicz
Keyword(s):  
Measurement Technique ◽  
Signal To Noise Ratio ◽  
Signal To Noise ◽  
Ratio Measurement ◽  
Noise Ratio

Determination of the Best Emulsion for the Microscopy of Crystals

1981 ◽  
Vol 39 ◽  
pp. 32-33
Author(s):  
David A. Grano ◽  
Kenneth H. Downing
Keyword(s):  
Spatial Frequency ◽  
Information Transfer ◽  
Signal To Noise Ratio ◽  
Experimental Situation ◽  
Photographic Emulsion ◽  
Modulation Transfer ◽  
Signal To Noise ◽  
Frequency Space ◽  
Noise Ratio

The retrieval of high-resolution information from images of biological crystals depends, in part, on the use of the correct photographic emulsion. We have been investigating the information transfer properties of twelve emulsions with a view toward 1) characterizing the emulsions by a few, measurable quantities, and 2) identifying the “best” emulsion of those we have studied for use in any given experimental situation. Because our interests lie in the examination of crystalline specimens, we've chosen to evaluate an emulsion's signal-to-noise ratio (SNR) as a function of spatial frequency and use this as our critereon for determining the best emulsion.The signal-to-noise ratio in frequency space depends on several factors. First, the signal depends on the speed of the emulsion and its modulation transfer function (MTF). By procedures outlined in, MTF's have been found for all the emulsions tested and can be fit by an analytic expression 1/(1+(S/S0)2). Figure 1 shows the experimental data and fitted curve for an emulsion with a better than average MTF. A single parameter, the spatial frequency at which the transfer falls to 50% (S0), characterizes this curve.

Experiments in Bright-Field Imaging with Hollow-Cone Illumination

1981 ◽  
Vol 39 ◽  
pp. 226-227
Author(s):  
W. Kunath ◽  
K. Weiss ◽  
E. Zeitler
Keyword(s):  
Signal To Noise Ratio ◽  
Carbon Support ◽  
Electronic System ◽  
Optic Axis ◽  
Hollow Cone ◽  
Signal To Noise ◽  
Bright Field ◽  
Noise Ratio ◽  
Single Field ◽  
Field Imaging

Bright-field images taken with axial illumination show spurious high contrast patterns which obscure details smaller than 15 ° Hollow-cone illumination (HCI), however, reduces this disturbing granulation by statistical superposition and thus improves the signal-to-noise ratio. In this presentation we report on experiments aimed at selecting the proper amount of tilt and defocus for improvement of the signal-to-noise ratio by means of direct observation of the electron images on a TV monitor.Hollow-cone illumination is implemented in our microscope (single field condenser objective, Cs = .5 mm) by an electronic system which rotates the tilted beam about the optic axis. At low rates of revolution (one turn per second or so) a circular motion of the usual granulation in the image of a carbon support film can be observed on the TV monitor. The size of the granular structures and the radius of their orbits depend on both the conical tilt and defocus.

Information capacity and bandwidth limitations in the SEM

1989 ◽  
Vol 47 ◽  
pp. 84-85
Author(s):  
D. C. Joy ◽  
R. D. Bunn
Keyword(s):  
Signal To Noise Ratio ◽  
Critical Dimension ◽  
Information Capacity ◽  
Acquisition Time ◽  
Signal To Noise ◽  
Sem Image ◽  
Probe Size ◽  
Minimum Number ◽  
Noise Ratio ◽  
Signal Channel

The information available from an SEM image is limited both by the inherent signal to noise ratio that characterizes the image and as a result of the transformations that it may undergo as it is passed through the amplifying circuits of the instrument. In applications such as Critical Dimension Metrology it is necessary to be able to quantify these limitations in order to be able to assess the likely precision of any measurement made with the microscope.The information capacity of an SEM signal, defined as the minimum number of bits needed to encode the output signal, depends on the signal to noise ratio of the image - which in turn depends on the probe size and source brightness and acquisition time per pixel - and on the efficiency of the specimen in producing the signal that is being observed. A detailed analysis of the secondary electron case shows that the information capacity C (bits/pixel) of the SEM signal channel could be written as :

Sign in / Sign up

Export Citation Format

Share Document