scholarly journals Spectroscopic flat-fields can be used for precision CCD gain and noise tests

2021 ◽  
Vol 38 ◽  
Author(s):  
J. Gordon Robertson
Keyword(s):  
Ccd Camera ◽  
Matched Pair ◽  
Optical Fibres ◽  
Charge Coupled Device ◽  
Small Areas ◽  
Flat Field ◽  
Basic Parameters ◽  
The Mean ◽  
A Charge ◽  
Analogue To Digital

Abstract One of the basic parameters of a charge coupled device (CCD) camera is its gain, that is, the number of detected electrons per output Analogue to Digital Unit (ADU). This is normally determined by finding the statistical variances from a series of flat-field exposures with nearly constant levels over substantial areas, and making use of the fact that photon (Poisson) noise has variance equal to the mean. However, when a CCD has been installed in a spectroscopic instrument fed by numerous optical fibres, or with an echelle format, it is no longer possible to obtain illumination that is constant over large areas. Instead of making do with selected small areas, it is shown here that the wide variation of signal level in a spectroscopic ‘flat-field’ can be used to obtain accurate values of the CCD gain, needing only a matched pair of exposures (that differ in their realisation of the noise). Once the gain is known, the CCD readout noise (in electrons) is easily found from a pair of bias frames. Spatial stability of the image in the two flat-fields is important, although correction of minor shifts is shown to be possible, at the expense of further analysis.

Description And Preliminary Performance Of A Charge-Coupled Device (CCD) Camera

1981 ◽  
Author(s):  
A. Bouere ◽  
J. Cretolle ◽  
B. Fort ◽  
R. Jouan ◽  
M. Gorisse ◽  
...  
Keyword(s):  
Ccd Camera ◽  
Charge Coupled Device ◽  
A Charge

Research on Magnet Excitation and Image Processing Used in Visual Detection

2011 ◽  
Vol 216 ◽  
pp. 793-797
Author(s):  
Li Bing Bai ◽  
Shu Lin Tian ◽  
Yu Hua Cheng
Keyword(s):  
Image Processing ◽  
Eddy Current ◽  
Visual Detection ◽  
Polarized Light ◽  
Ccd Camera ◽  
Experimental Tests ◽  
Laser Source ◽  
Magnetic Excitation ◽  
Charge Coupled Device ◽  
A Charge

A novel visual detection set, which can detect sub-superficial defects in conductive specimens, is presented in this paper. The set has a laser source, a charge coupled device (CCD) camera, and a magnetic excitation. The linear polarized light given off by the laser source is modulated by the superimposition of the magnetic fields induced by the coil and eddy current, and acquired by the CCD. Given the exciting current is known and the eddy current is influenced by the defects, the information of defects can be extracted from the image acquired by CCD. The magnet excitation and image processing are described in detail. Experimental tests have been done and the method presented is proved by the experimental results.

Using laser speckle to measure the roughness of paper

TAPPI Journal ◽  
2011 ◽  
Vol 10 (3) ◽  
pp. 7-13
Author(s):  
ABDIEL PINO ◽  
JOSEP PLADELLORENS ◽  
JOSEP F. COLOM ◽  
ORIOL CUSOLA ◽  
AGUSTÍN TOSAS
Keyword(s):  
Image Processing ◽  
Speckle Pattern ◽  
Ccd Camera ◽  
Laser Speckle ◽  
Charge Coupled Device ◽  
Paper Surface ◽  
Surface Profiling ◽  
Base Paper ◽  
Occurrence Matrix ◽  
A Charge

Paper surface roughness is an important consideration in paper and board destined for printing. The amount of coating and method of application depend on the roughness of the base paper. We present a method to measure the roughness of the paper based on analysis of speckle pattern on the surface. Images are captured by means of a simple configuration using a laser and a charge-coupled device (CCD) camera. Then, we apply digital image processing using a co-occurrence matrix, providing for a noncontact surface profiling method that can be used online.

Single-Shot Multiwavelength Imaging of Laser Plumes

1998 ◽  
Vol 52 (2) ◽  
pp. 179-186 ◽  
Author(s):  
Matthew P. Nelson ◽  
Wendy C. Bell ◽  
Michael L. McLester ◽  
M. L. Myrick
Keyword(s):  
Fiber Optics ◽  
Optical Fibers ◽  
Ccd Camera ◽  
Chemical Imaging ◽  
Single Shot ◽  
Charge Coupled Device ◽  
Breakdown Spectroscopy ◽  
Laser Induced Breakdown ◽  
Optic Array ◽  
A Charge

A novel optical approach to single-shot chemical imaging with high spectroscopic resolution is described with the use of a prototype dimension-reduction fiber-optic array. Images are focused onto a 30 × 20 array of hexagonally packed 250 μm o.d. f/2 optical fibers that are drawn into a 600 × 1 distal array with specific ordering. The 600 × 1 side of the array is imaged with an f/2 spectrograph equipped with a holographic grating and a charge-coupled device (CCD) camera for spectral analysis. Software is used to extract the spatial/spectral information contained in the CCD images and de-convolute them into wavelength-specific reconstructed images or position-specific spectra that span a 190 nm wavelength space. “White light” zero-order images and first-order spectroscopic images of laser plumes have been reconstructed to illustrate proof-of-principle. Index Headings: Fiber optics; Chemical imaging; Spectroscopic imaging; Charged-coupled device (CCD); Laser-induced breakdown spectroscopy (LIBS).

Profiling of Redox Atmosphere in Flames by Chemical Seeding/Planar Laser-Induced Fluorescence (CS/PLIF)

2005 ◽  
Vol 128 (4) ◽  
pp. 765-772 ◽  
Author(s):  
K. Kitagawa ◽  
S. Itoh ◽  
N. Arai ◽  
Ashwani K. Gupta
Keyword(s):  
Rotational Temperature ◽  
Thermal Dissociation ◽  
Flame Temperature ◽  
Ccd Camera ◽  
Laser Induced Fluorescence ◽  
Charge Coupled Device ◽  
Planar Laser ◽  
A Charge ◽  
Local Value ◽  
Redox Index

Knowledge on the local value of reducing and oxidizing (redox) atmospheres in flames is among the most important issues to be desired by combustion engineers. In this study, the spatial distribution of a redox atmosphere in flames has been measured experimentally by the chemical seeding/laser-induced fluorescence (CS/LIF) technique. A solution of iron was sprayed into a premixed propane-air flame supported on a slot burner. The LIF intensity of FeO band was compared to that of a Fe line to estimate the experimentally determined degree of atomization in the reaction FeO→Fe+O. The flame temperature profile was determined as a rotational temperature and was obtained by comparing the LIF (laser-induced fluorescence) intensities of OH rotational lines. The degree of atomization was theoretically calculated on the basis that simple thermal dissociation takes place in the reaction. The redox atmosphere, or a redox index, is defined as the ratio of the experimentally determined to theoretically calculated degrees of atomization. Two-dimensional distributions or profiles of the excitation temperature, experimentally determined degree of atomization, and redox index have been measured using a charge coupled device (CCD) camera fitted with an optical bandpass filter and the associated signal processing using a computer. This method has been successfully applied to quantitatively illustrate the local atmosphere and profile of the redox atmosphere in flames.

Image Information Obtained Using a Charge-Coupled Device (CCD) Camera During an Immersion Liquid Evaporation Process for Measuring the Refractive Index of Solid Particles

2018 ◽  
Vol 72 (6) ◽  
pp. 908-912 ◽  
Author(s):  
Ilpo Niskanen ◽  
Veijo Sutinen ◽  
Göran Thungström ◽  
Jukka Räty
Keyword(s):  
Refractive Index ◽  
Physical Property ◽  
Ccd Camera ◽  
Solid Particles ◽  
Evaporation Process ◽  
Immersion Liquid ◽  
Refractive Index Measurement ◽  
Charge Coupled Device ◽  
Liquid Evaporation ◽  
A Charge

The refractive index is a fundamental physical property of a medium, which can be used for the identification and purity issues of all media. Here we describe a refractive index measurement technique to determine simultaneously the refractive index of different solid particles by monitoring the transmittance of light from a suspension using a charge-coupled device (CCD) camera. An important feature of the measurement is the liquid evaporation process for the refractive index matching of the solid particle and the immersion liquid; this was realized by using a pair of volatile and non-volatile immersion liquids. In this study, refractive indices of calcium fluoride (CaF2) and barium fluoride (BaF2) were determined using the proposed method.

A new machine-vision-based approach for rapid dimensional inspection of an integrated circuit carrier tape

2009 ◽  
Vol 223 (3) ◽  
pp. 145-154
Author(s):  
S-H Chen ◽  
T-T Liao ◽  
C-T Chen
Keyword(s):  
Machine Vision ◽  
Integrated Circuit ◽  
Ccd Camera ◽  
Light Sources ◽  
Charge Coupled Device ◽  
Lighting Conditions ◽  
Environmental Lighting ◽  
Canny Edge ◽  
Edge Detection Method ◽  
A Charge

This study presents a rapid and reliable machine vision technique for measuring the principal features of interest in an integrated circuit carrier tape, namely the diameters of the circular sprocket perforations and centre hole, the width of the carrier tape, and the width and length of the centre cavity. In performing the measurement process, the quality of the image acquisition process is enhanced by using two auxiliary light sources to suppress the effects of natural variations in the environmental lighting conditions. Having acquired the image using a charge coupled device (CCD) camera, the features of interest are separated from the background region of the image using a two-threshold algorithm based on the Otsu threshold selection method. The edge of each feature is then extracted from the binary image using the Canny edge detection method. The dimensions of the circular features are obtained by fitting four right-angle triangles within the periphery of the extracted circular edge and then computing the circle diameter by taking the mean of the hypotenuse values of the four triangles as computed using the Pythagorean theorem.

Dynamic Response of a Sphere Immersed in a Shallow Water Flow

2014 ◽  
Vol 136 (2) ◽  
Author(s):  
D. Mirauda ◽  
A. Volpe Plantamura ◽  
S. Malavasi
Keyword(s):  
Free Surface ◽  
Dynamic Response ◽  
Surface Current ◽  
Ccd Camera ◽  
The Body ◽  
Mass Ratio ◽  
Shallow Water Flow ◽  
Charge Coupled Device ◽  
Current Flows ◽  
A Charge

This work analyzes the dynamic response of a sphere located close to the floor of a hydraulic channel within steady free-surface current flows. The sphere is free to move in transverse (y) and streamwise (x) directions, and it is characterized by a mass ratio m* equal to 1.34. The oscillation amplitudes and the frequencies of the sphere have been measured by means of the image analysis of a charge coupled device (CCD) camera. The experimental data show a significant influence of the free surface on the sphere movement and highlight a different behavior of the dynamic response to the increasing of the water level on the upper part of the body.

EELS in the High-Resolution STEM

1992 ◽  
Vol 50 (2) ◽  
pp. 1246-1247
Author(s):  
L. M. Brown
Keyword(s):  
Super Resolution ◽  
Ccd Camera ◽  
Bright Field ◽  
Charge Coupled Device ◽  
Electron Microscopes ◽  
A Charge ◽  
Convergent Beam ◽  
Electron Energy Loss ◽  
Beam Patterns ◽  
Electron Energy Loss Spectra

The advent of efficient parallel recording systems for electron energy-loss spectra in electron microscopes, particularly those equipped with field emission guns which permit the formation of a useful nanometre probe, has transformed these instruments into remarkably versatile tools for solid state science. It is now possible in one's own laboratory to acquire spectra of quality comparable to those obtained from dedicated synchrotron sources, and in addition to record energy-filtered convergent-beam patterns and energy-selected images, in addition to the usual STEM outputs.The system in use in our laboratory has been developed by McMullan and co-workers. Its main feature is the use of a charge-coupled device to record both spectra and convergent beam patterns. The system is under constant development, and in its latest version offers a choice of three detectors: a slow scan CCD camera for PEELS and microdiffraction (CBED from the probe optimised for best spatial resolution); a TV-rate CCD for rapid readout, instrument alignment and ‘super-resolution’ experiments; and a specialised scintillator-photomultiplier bright-field detector.

scholarly journals A study of random phased laser spots

1995 ◽  
Vol 13 (4) ◽  
pp. 469-480 ◽  
Author(s):  
T. Ceccotti ◽  
S. Bastiani ◽  
S. Bastiani ◽  
A. Giulietti ◽  
V. Biancalana ◽  
...  
Keyword(s):  
Random Phase ◽  
Ccd Camera ◽  
Diffraction Theory ◽  
Probability Density Distribution ◽  
Charge Coupled Device ◽  
Laser Plasma Interactions ◽  
Pattern Structures ◽  
Phase Plates ◽  
A Charge ◽  
Pulsed Laser Beam

Far-field images produced using different random phase plates on a pulsed laser beam focused with variousf/numbers were recorded by a charge-coupled device (CCD) camera and then analyzed. Envelope spot sizes agree with diffraction theory while mean sizes of the pattern structures have been found to be larger than the diffraction limit. The probability density distribution of intensity in the focal plane is not the expected exponential. A central symmetry of the pattern has also been seen after suitably aperturing the beam. Some consequences for the use of powerful RPP-treated laser beams in laser-plasma interactions are discussed.

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