COMPARISON OF ALGORITHMS FOR DETERMINING THE THICKNESS OF OPTICAL COATING LAYERS BASED ON THE MONOCHROMATIC MONITORING DATA

2021 ◽  
Vol 9 (4) ◽  
pp. 89-99
Author(s):  
A. V. Tikhonravov ◽  
◽  
Iu. S. Lagutin ◽  
A. A. Lagutina ◽  
D. V. Lukyanenko ◽  
...  
Keyword(s):  
Inverse Problem ◽  
Reverse Engineering ◽  
Deposition Process ◽  
Systematic Errors ◽  
Engineering Problem ◽  
Optical Coatings ◽  
Random Errors ◽  
Local Algorithms ◽  
On Line ◽  
Non Local

The reverse engineering problem of determining the layer thicknesses of deposited optical coatings from on-line monochromatic measurements is considered. To solve this inverse problem, non-local algorithms are proposed that use all the data accumulated during the deposition process. For the proposed algorithms, the accuracy of solving the inverse problem is compared in the presence of random and systematic errors. It is shown that in the case when the measured data contains only random errors, the best accuracy is provided by the algorithm based on minimizing the discrepancy functional. In the case of systematic errors, the advantage of one the algorithms based on minimizing the variance functionals is demonstrated. Key words: inverse problems, reverse engineering, optical coatings, thin films.

scholarly journals Daily patient geometry correction: application of NAL and eNAL protocols

2020 ◽  
Vol 26 (4) ◽  
pp. 181-184
Author(s):  
Andrzej Dąbrowski ◽  
Sylwia Zielińska-Dąbrowska ◽  
Tomasz Kuszewski ◽  
Krzysztof Lis
Keyword(s):  
Systematic Errors ◽  
Random Errors ◽  
Raw Data ◽  
Total Displacement ◽  
Displacement Vectors ◽  
Daily Data ◽  
Online Corrections ◽  
On Line ◽  
Patient Setup ◽  
Set Up

AbstractPurpose: To test the NAL and eNAL correction protocols using daily patient setup displacements.Methods and material: In total, the analysis was performed for 749 and 797 kV CBCT images for gynecological and prostate patients, respectively, each of 30 patients. After the planning procedure, patients were set up on the treatment table in the treatment position every day. The on-line correction protocol was applied. KV CBCT images were acquired by means of x-ray lamp mounted orthogonally on Linac. Patient setup displacement was assigned. NAL and eNAL corrections protocols were simulated using daily data from online corrections for these two groups of patients. The overall systematic error and random error were calculated for each direction.Results: For the prostate group, the random errors for daily Raw data (no correction) in LAT, LONG, and VERT directions were 2.0 mm, 1.6 mm, and 3.2 mm, respectively. For NAL and eNAL protocols, they were in the range of 1.8 mm to 3.2 mm. For the gynecological group, the random errors were: for daily Raw data 2.2 mm, 1.7 mm, and 3.2 mm, respectively. For NAL and eNAL protocols, they were in the range of 2.0 to 3.4 mm.For the prostate group, values of systematic errors 1.8 mm, 1.8 mm, and 3.3 mm, respectively for Raw data. For NAL and eNAL protocols, these values were less than 1.8 mm. For the gynecological group, the systematic errors were 2.6 mm, 2.3 mm, and 2.8 mm, respectively, for Raw data. For NAL ana eNAL protocols less than 1.8 mm.For the gynecological group, for Raw data, 45% of the total displacement vectors exceeded 5 mm, whereas only 25% did after the NAL procedure and 29% after the eNAL procedure. For the prostate group, for Raw data, 34% of the total displacement vectors exceeded 5 mm, whereas only 22% did after NAL procedure and 28% after eNAL procedure Conclusions: For gynecological and prostate cancer patients, the NAL and eNAL correction protocols can be safely applied to substantially reduce setup errors.

Statistics and parallaxes

1978 ◽  
Vol 48 ◽  
pp. 7-29
Author(s):  
T. E. Lutz
Keyword(s):  
Experimental Design ◽  
Statistical Methods ◽  
Review Paper ◽  
Systematic Errors ◽  
Past Experience ◽  
Random Errors ◽  
Trigonometric Parallaxes ◽  
Systematic And Random Errors

This review paper deals with the use of statistical methods to evaluate systematic and random errors associated with trigonometric parallaxes. First, systematic errors which arise when using trigonometric parallaxes to calibrate luminosity systems are discussed. Next, determination of the external errors of parallax measurement are reviewed. Observatory corrections are discussed. Schilt’s point, that as the causes of these systematic differences between observatories are not known the computed corrections can not be applied appropriately, is emphasized. However, modern parallax work is sufficiently accurate that it is necessary to determine observatory corrections if full use is to be made of the potential precision of the data. To this end, it is suggested that a prior experimental design is required. Past experience has shown that accidental overlap of observing programs will not suffice to determine observatory corrections which are meaningful.

Precise on-line Measurement of Lattice Vectors

1990 ◽  
Vol 48 (1) ◽  
pp. 530-531
Author(s):  
W.J. de Ruijter ◽  
Sharma Renu
Keyword(s):  
Electron Microscope ◽  
Measurement Errors ◽  
Dynamic Range ◽  
Structural Information ◽  
Statistical Parameter ◽  
Systematic Errors ◽  
Geometric Distortion ◽  
Crystal Silicon ◽  
Camera System ◽  
On Line

Established methods for measurement of lattice spacings and angles of crystalline materials include x-ray diffraction, microdiffraction and HREM imaging. Structural information from HREM images is normally obtained off-line with the traveling table microscope or by the optical diffractogram technique. We present a new method for precise measurement of lattice vectors from HREM images using an on-line computer connected to the electron microscope. It has already been established that an image of crystalline material can be represented by a finite number of sinusoids. The amplitude and the phase of these sinusoids are affected by the microscope transfer characteristics, which are strongly influenced by the settings of defocus, astigmatism and beam alignment. However, the frequency of each sinusoid is solely a function of overall magnification and periodicities present in the specimen. After proper calibration of the overall magnification, lattice vectors can be measured unambiguously from HREM images.Measurement of lattice vectors is a statistical parameter estimation problem which is similar to amplitude, phase and frequency estimation of sinusoids in 1-dimensional signals as encountered, for example, in radar, sonar and telecommunications. It is important to properly model the observations, the systematic errors and the non-systematic errors. The observations are modelled as a sum of (2-dimensional) sinusoids. In the present study the components of the frequency vector of the sinusoids are the only parameters of interest. Non-systematic errors in recorded electron images are described as white Gaussian noise. The most important systematic error is geometric distortion. Lattice vectors are measured using a two step procedure. First a coarse search is obtained using a Fast Fourier Transform on an image section of interest. Prior to Fourier transformation the image section is multiplied with a window, which gradually falls off to zero at the edges. The user indicates interactively the periodicities of interest by selecting spots in the digital diffractogram. A fine search for each selected frequency is implemented using a bilinear interpolation, which is dependent on the window function. It is possible to refine the estimation even further using a non-linear least squares estimation. The first two steps provide the proper starting values for the numerical minimization (e.g. Gauss-Newton). This third step increases the precision with 30% to the highest theoretically attainable (Cramer and Rao Lower Bound). In the present studies we use a Gatan 622 TV camera attached to the JEM 4000EX electron microscope. Image analysis is implemented on a Micro VAX II computer equipped with a powerful array processor and real time image processing hardware. The typical precision, as defined by the standard deviation of the distribution of measurement errors, is found to be <0.003Å measured on single crystal silicon and <0.02Å measured on small (10-30Å) specimen areas. These values are ×10 times larger than predicted by theory. Furthermore, the measured precision is observed to be independent on signal-to-noise ratio (determined by the number of averaged TV frames). Obviously, the precision is restricted by geometric distortion mainly caused by the TV camera. For this reason, we are replacing the Gatan 622 TV camera with a modern high-grade CCD-based camera system. Such a system not only has negligible geometric distortion, but also high dynamic range (>10,000) and high resolution (1024x1024 pixels). The geometric distortion of the projector lenses can be measured, and corrected through re-sampling of the digitized image.

Quality Control of Multichannel Hematology Analyzers: Bivariate On-line Comparison of MCV and MCH Values for the Detection of Random Errors

1992 ◽  
Vol 97 (5) ◽  
pp. 645-651
Author(s):  
Veli Kairisto ◽  
Timo Kouri ◽  
Allan Rajamäki ◽  
Arja Virtanen ◽  
Esa Uusipaikka ◽  
...  
Keyword(s):  
Quality Control ◽  
Random Errors ◽  
On Line ◽  
Hematology Analyzers

scholarly journals Novel Robust Design Method of Multilayer Optical Coatings

ISRN Optics ◽  
2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Suyong Wu ◽  
Xingwu Long ◽  
Kaiyong Yang
Keyword(s):  
Robust Design ◽  
Optimization Design ◽  
Design Method ◽  
Analytical Calculation ◽  
Design Procedure ◽  
Deposition Process ◽  
Practical Significance ◽  
Optical Coatings ◽  
Optical Films ◽  
Robust Design Method

We present a novel fast robust design method of multilayer optical coatings. The sensitivity of optical films to production errors is controlled in the whole optimization design procedure. We derive an analytical calculation model for fast robust design of multilayer optical coatings. We demonstrate its effectiveness by successful application of the robust design method to a neutral beam splitter. It is showed that the novel robust design method owns an inherent fast computation characteristic and the designed film is insensitive to the monitoring thickness errors in deposition process. This method is especially of practical significance to improve the mass production yields and repetitive production of high-quality optical coatings.

Establishing inherent uncertainty in the shifts determined by volumetric imaging

2017 ◽  
Vol 16 (3) ◽  
pp. 258-264
Author(s):  
Upendra Kumar Giri ◽  
Anirudh Pradhan
Keyword(s):  
Linear Accelerator ◽  
Systematic Errors ◽  
Cone Beam ◽  
Random Errors ◽  
Mean Values ◽  
Volumetric Imaging ◽  
X Ray ◽  
Image Quality Control ◽  
The Mean ◽  
Six Degree Of Freedom

AbstractObjectiveThis study was conducted for establishing inherent uncertainty in the shift determination by X-ray volumetric imaging (XVI) and calculating margins due to this inherent uncertainty using van Herk formula.Material and methodsThe study was performed on the XVI which was cone-beam computed tomography integrated with the Elekta AxesseTM linear accelerator machine having six degree of freedom enabled HexaPOD couch. Penta-Guide phantom was used for inherent translational and rotational shift determination by repeated imaging. The process was repeated 20 times a day without moving the phantom for 30 consecutive working days. The measured shifts were used for margins calculation using van Herk formula.ResultsThe mean standard deviations were calculated as 0·05, 0·05, 0·06 mm in the three translational (x, y and z) and 0·05°, 0·05°, 0·05° in the three rotational axes (about x, y, z). Paired sample t-test was performed between the mean values of translational shifts (x, y, z) and rotational shifts. The systematic errors were found to be 0·03, 0·04 and 0·03 mm while the random errors were 0·05, 0·06 and 0·06 mm in the lateral, cranio-caudal and anterio-posterior directions, respectively. For the rotational shifts, the systematic errors were 0·02, 0·03 and 0·03 and the random errors were 0·06, 0·05 and 0·05 in the pitch, roll and yaw directions, respectively.ConclusionOur study concluded that there was an inherent uncertainty associated with the XVI tools, on the basis of these six-dimensional shifts, margins were calculated and recorded as a baseline for the quality assurance (QA) programme for XVI imaging tools by checking its reproducibility once in a year or after any major maintenance in hardware or upgradation in software. Although the shift determined was of the order of submillimetre order, still that shift had great significance for the image quality control of the XVI tools. Every departments practicing quality radiotherapy with such imaging tools should establish their own baseline value of inherent shifts and margins during the commissioning and must use an important QA protocol for the tools.

Utilisation d'une ligne de microphotodiodes en spectroscopie dispersive : application à la détection du NO2

1983 ◽  
Vol 61 (2) ◽  
pp. 301-304 ◽  
Author(s):  
Jacques Bures ◽  
François Leonard ◽  
Jean-Pierre Monchalin
Keyword(s):  
Absorption Spectrum ◽  
Systematic Errors ◽  
Sufficient Information ◽  
Atmospheric Pollutant ◽  
Spatial Frequencies ◽  
Low Pass ◽  
On Line ◽  
Photodiode Array ◽  
Analysis System

A self-scanned photodiode array has been used as a multiplex sensor for laboratory detection and measurement, by dispersive spectroscopy, of trace quantities of the atmospheric pollutant NO2. The on-line data acquisition and numerical analysis system allows in particular to eliminate some systematic errors and drifts (Taylor filtering) and the noise associated with high spatial frequencies (low-pass filtering). We have then been able to show that an absorption spectrum, corresponding to low absorber concentrations, has a sufficient information content for the characterization of the pollutant and the measurement of its concentration (ppm m), even when noise and drifts are present. The proposed system can be favorably compared to the ones, based on a single photoelectric detector, which are commercially used.

scholarly journals STUDI PERAMBATAN KESALAHAN SISTEMATIS LUAS LAHAN PARKIR KAMPUS MENGGUNAKAN PENDEKATAN LUAS SEGITIGA SEMBARANG

2019 ◽  
Vol 13 (1) ◽  
pp. 14
Author(s):  
Hendro Supratikno ◽  
David Premana
Keyword(s):  
Systematic Error ◽  
Error Propagation ◽  
Measurement Data ◽  
Systematic Errors ◽  
Random Errors ◽  
Land Area ◽  
Parking Lots ◽  
Parking Lot ◽  
Data Error ◽  
Definition Of

Parking is a condition of not moving a vehicle that is temporary because it was abandoned by the driver. Included in the definition of parking is every vehicle that stops at certain places whether stated by traffic signs or not, and not solely for the benefit of raising and / or lowering people and / or goods.Campus 3 Lumajang State Community Academy has facilities and infrastructure prepared by the Lumajang Regency government. However, the parking lots provided cannot accommodate vehicles optimally because of the ratio of the number of vehicles and the area of the parking area that is not appropriate. This is because the area of the parking lot is not analyzed by data error when measuring.Each measurement data is assumed to have errors both systematic errors, random errors, and large errors (blunders), so that in the measurement of parking lots certainly there are errors. From this the authors intend to conduct research to find out how the propagation of systematic errors and the large systematic errors of the area of campus parking lot 3 Lumajang Community Academy.The methods used in this study include preparing materials and tools, making land sketches, decomposing them, determining distances using theodolite, determining land area equations, and finding systematic error propagation. So that the final goal in this study is to find large systematic errors in the parking area of Campus 3 of the Lumajang State Community Academy

scholarly journals Calculating Point Cloud Object Volume Using Co-Opposite-Direction Slicing Method

2019 ◽  
Author(s):  
Bin Li ◽  
Xiaowei Bi ◽  
Cheng Peng ◽  
Yong Chen ◽  
Xiaofa Zhao ◽  
...  
Keyword(s):  
Full Advantage ◽  
Opposite Direction ◽  
Point Cloud ◽  
Systematic Errors ◽  
Random Errors ◽  
Improved Method ◽  
Cone Model ◽  
Slicing Method

Although the Slicing Method (SM) is effective for calculating the volume of point cloud objects (PCOs), it is restricted in terms of applicability and practicability because of a certain contingency and directional defects. The Co-Opposite-Direction Slicing Method (CODSM) proposed in this paper is an improved method for calculating PCO volume by increasing parallel (co-opposite-direction) observation and considering the two-way mean as the result. This method takes full advantage of the mutual offsetting of random errors and the compensation of systematic directional errors, which can effectively overcome (or mitigate) the effect of random errors and reduce the effect of systematic errors in SM. In this paper, two typical objects, a cone model and a stone lion base, are the examples for calculating PCO volume using CODSM. The results show that CODSM has all the inherent advantages of SM and effectively weakens the volatility of random errors and the directionality of systematic errors from SM. Therefore, CODSM is a robust configuration upgrade of SM.

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