The Construction Basis of High-Precision Optical Range Finder GD-j1(l)

2018 ◽  
Vol 931 ◽  
pp. 681-686
Author(s):  
Hovsep S. Petrosyan ◽  
Yegisabeth H. Hayrapetyan ◽  
Hovnan A. Hunanyan
Keyword(s):  
High Precision ◽  
Linear Measurement ◽  
High Accuracy ◽  
Compensation Method ◽  
Interference Method ◽  
Modulation Method ◽  
Range Finder ◽  
Optical Range ◽  
Linear Measurements ◽  
Measurement Devices

The methods of construction of high-precision rangefinder on the modulation method, which will complement the means of linear measurements on the interference method, are considered. The linearly compensation method, which leads to the possibility of implementing range finders with an error of mφ=0.01 mm, is proposed as the basic constructions of extremely high accuracy linear measurement devices.

scholarly journals High-precision two-phase laser rangefinder PFSD-1,2

2019 ◽  
Vol 97 ◽  
pp. 06042 ◽  
Author(s):  
Yegisabeth Hayrapetyan ◽  
Hovseph Petrosyan ◽  
Hovnan Hunanyan ◽  
Artyom Tsaturyan
Keyword(s):  
High Precision ◽  
Phase Error ◽  
Technical Problem ◽  
Experimental Studies ◽  
Modulation Method ◽  
Phase Plate ◽  
Linear Measurements ◽  
High Quality ◽  
Two Phase ◽  
Phase Cycle

Performing high-precision linear measurements is one of the main tasks of modern engineering geodesy. Consequently, the development and creation of high-precision laser rangefinders and refractometers with a relative measurement error of not more than 3.10-7, becomes an urgent scientific and technical problem. Wide theoretical and experimental studies in the problem laboratory of geodetic measurements of NUACA have accumulated a sufficient amount of experimental results for the construction of modern high-precision light meter with the determination of the residual part of the phase cycle with an error of 0.03-0.05 mm. The article discusses issues related to improving the accuracy of linear measurements developed in the NUACA of high-precision light rangefinder. A two-phase modulation measurement method is proposed, when signals shifted by 180° are formed optically using a phase plate at λ/2. This modulation method of linear measurements provided the phase error of linear measurements mφ = 0.03-0.05 mm. The article also discusses the issue of reducing the modulation power. For this purpose, it is proposed to install a high-quality buffer Q-resonator between the high-quality light modem and the low-quality microwave oscillator.

scholarly journals Assessment of necessity of neuronavigation in localization of calvarial extra-axial lesions in the setting of limited resources

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Hussein Soffar ◽  
Mohamed F. Alsawy
Keyword(s):  
Conventional Method ◽  
Linear Measurement ◽  
Limited Resources ◽  
Linear Measurements ◽  
Surgical Interventions ◽  
Localization Method ◽  
Mean Error ◽  
Significant Difference ◽  
The Mean ◽  
Mean Time

Abstract Background Neuronavigation is a very beneficial tool in modern neurosurgical practice. However, the neuronavigation is not available in most of the hospitals in our country raising the question about its importance in localizing the calvarial extra-axial lesions and to what extent it is safe to operate without it. Methods We studied twenty patients with calvarial extra-axial lesions who underwent surgical interventions. All lesions were preoperatively located with both neuronavigation and the usual linear measurements. Both methods were compared regarding the time consumed to localize the tumor and the accuracy of each method to anticipate the actual center of the tumor. Results The mean error of distance between the planned center of the tumor and the actual was 6.50 ± 1.762 mm in conventional method, whereas the error was 3.85 ± 1.309 mm in IGS method. Much more time was consumed during the neuronavigation method including booting, registration, and positioning. A statistically significant difference was found between the mean time passed in the conventional method and IGS method (2.05 ± 0.826, 24.90 ± 1.334, respectively), P-value < 0.001. Conclusion In the setting of limited resources, the linear measurement localization method seems to have an accepted accuracy in the localization of calvarial extra-axial lesions and it saves more time than neuronavigation method.

scholarly journals Face morphology of brazilian and peruvian populations: analysis of proportion and linear measurement indexes

2017 ◽  
Vol 20 (3) ◽  
Author(s):  
Elaine Cristina Sousa Dos Santos ◽  
Diego Jesus Bradariz Pimentel ◽  
Laís Lopes Machado De Matos ◽  
Laís Valencise Magri ◽  
Ana Maria Bettoni Rodrigues Da Silva ◽  
...  
Keyword(s):  
Latin American ◽  
Linear Measurement ◽  
Linear Measurements ◽  
3D Images ◽  
Brazilian Sample ◽  
Face Width ◽  
The Face ◽  
Mouth Width ◽  
3D Stereophotogrammetry ◽  
Face Morphology

<p><strong>Objective: </strong>To compare the proportion and linear measurement indexes between Brazilian and Peruvian population through 3D stereophotogrammetry and to stablish the face profile of these two Latin American populations. <strong>Material and Methods: </strong>40 volunteers (Brazilian n=21– 10 males and 11 females; Peruvian n=19 – 8 males and 11 females) aged between 18 and 40 years (mean of 28.7±9.1) had landmarks marked on the face. Then, 3D images were obtained (VECTRA M3) and the indexes of proportion and linear measurement (face, nose, and lips) were calculated. The data were statistically analyzed by One-Way ANOVA (p&lt;0.05). <strong>Results: </strong>The proportion indexes did not reveal marked differences either between the studied populations or genders (p&gt;0.05). The following linear measurements showed intergroup statistically significant differences: face width and height, nose width and height, upper facial height, mouth width, protrusion of the nose tip (p&lt;0.05). The Brazilian females showed the smallest significant differences. <strong>Conclusions: </strong>Despite the different ethnic compositions, the Brazilian and Peruvian populations did not differ regarding the proportions of the face, nose, and lips. The differences observed in Brazilian females may be related to gender and/or to the Caucasian heritage of the Brazilian sample.</p><p><strong>Keywords</strong></p><p>Photogrammetry; Face; Tridimensional Image.<strong></strong></p>

Experience and results obtained at the ESRF with high-precision air bearing motion systems

2011 ◽  
Vol 1 (MEDSI-6) ◽  
Author(s):  
P. Marion ◽  
L. Ducotte ◽  
M. Nicola ◽  
H. P. van der Kleij ◽  
L. Eybert ◽  
...  
Keyword(s):  
High Precision ◽  
High Accuracy ◽  
Air Bearing ◽  
Air Bearings ◽  
Positioning Accuracy ◽  
Point Of Interest ◽  
Air Film

In high-accuracy motion stages, the positioning accuracy at the point of interest is strongly influenced by guiding errors: for translation motions, straightness errors and angular errors (pitch, yaw and roll); for rotation motions, axial, radial and tilt errors. When air bearings are used for guiding, the air film averages out local irregularities of bearings surfaces, which helps reduce guiding errors considerably. Some results obtained with air bearing precision systems designed and manufactured by specialized companies and tested at ESRF are described below.

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