scholarly journals Optical Control System for Displacement Monitoring of the High Precision Measurement Setup Elements

Author(s):  
Victor V. Kholkin ◽  
Vladimir Yu. Kholkin

Introduction. It is necessary to ensure the reliability of measurements when operating high-precision measurement setups. The elements displacement of the measurement path introduces measurement results distortions, especially in measurement setups operating in the microwave range. It is necessary to monitor the elements positions of the measurement setup to ensure the measurements reliability. The monitoring should be performed during the measurement, and the control device should be connected to the automatic control system of the measurement setup, and it should neither mechanically affect the setup elements nor introduce the electrical and electromagnetic interferences.Objective. The objective of the present work is a design of the control system, which allows monitoring of elements displacements of the high precision measuring setup with an accuracy of 1.0·10–4 mm. And the designed control system should neither mechanically affect the controlled elements nor introduce the electrical and electromagnetic interferences, thus allowing the digital signal processing.Materials and methods. The designed system utilizes optical methods of the displacements monitoring, which are based on the geometric optics principles. The charge-coupled devices (CCD) to record the system response to optical path changes are used.Results. Two designs of the control system for the displacement monitoring of the high precision measurement setup elements are presented. The first system design allows detecting the elements displacement occurrence, and the second system design allows to identify the displaced element. The system is capable to register the elements displacements with accuracy of 1.0·10–4 mm and monitor the elements positions while vibration exposures. The system does not mechanically or electromagnetically affect the controlled elements. All system elements are resistant to the microwave radiation and increased background radiation, excluding CCD that should be placed outside the active zone. The mathematical simulation allows assessing the sensitivity of the designed optical control system. The system sensitivity increasing method by the optical path increasing and corrective reflector using is proposed.Conclusion. The designed control system for the displacements monitoring of the high precision measurement setup elements meets the requirements imposed on it. The system allows the digital signal processing and can withstand the increased microwave, X-ray and background radiation. The designed system is much simpler to implement in comparison with systems based on other physical principles. The novelty of the control system technical solution is confirmed by the patent. 


2019 ◽  
Vol 52 (5-6) ◽  
pp. 462-472
Author(s):  
He Huang ◽  
Jingxue Ni ◽  
Huifeng Wang ◽  
Jiajia Zhang ◽  
Rong Gao ◽  
...  

In view of the strict requirements of the current high-precision measurement system for stable output power of the semiconductor LD (Laser Diode), a semiconductor LD stable power drive and multi-closed-loop control system are proposed after analyzing the semiconductor laser’s P–I (Power–Current) characteristics and temperature characteristics. The system uses a microcontroller as the core control unit and realizes the stable power output control of the semiconductor laser by controlling the current, power and temperature parameters. In this system, first, the control structure model of the controlled object has been designed. Second, a controllable closed-loop constant current feedback drive circuit has been designed and a high-precision controllable constant current drive circuit of the semiconductor laser has been obtained. Furthermore, the control circuit has been designed based on the neural PI (Proportional-Integral) control model and realizes the short-term stable power output of the semiconductor LD. Finally, a closed-loop temperature control system is designed to ensure that the operating temperature of the semiconductor laser is relatively stable and a long-term stable power output is obtained. By designing the hardware and software of the control system and conducting long-term experiments in the laboratory, we found that the system can guarantee the output power within 1 W of PD (Proportional-Differential) LD, and its long-term power stability can reach 1%. This system has a certain reference significance in using semiconductor lasers for high-quality detection when there are stringent requirements for power.





1991 ◽  
Vol 1 (12) ◽  
pp. 1669-1673 ◽  
Author(s):  
Hans Gerd Evertz ◽  
Martin Hasenbusch ◽  
Mihail Marcu ◽  
Klaus Pinn ◽  
Sorin Solomon




Radiocarbon ◽  
2020 ◽  
pp. 1-13
Author(s):  
Alexandra Fogtmann-Schulz ◽  
Sabrina G K Kudsk ◽  
Florian Adolphi ◽  
Christoffer Karoff ◽  
Mads F Knudsen ◽  
...  

ABSTRACT We here present a comparison of methods for the pretreatment of a batch of tree rings for high-precision measurement of radiocarbon at the Aarhus AMS Centre (AARAMS), Aarhus University, Denmark. The aim was to develop an efficient and high-throughput method able to pretreat ca. 50 samples at a time. We tested two methods for extracting α-cellulose from wood to find the most optimal for our use. One method used acetic acid, the other used HCl acid for the delignification. The testing was conducted on background 14C samples, in order to assess the effect of the different pretreatment methods on low-activity samples. Furthermore, the extracted wood and cellulose fractions were analyzed using Fourier transform infrared (FTIR) spectroscopy, which showed a successful extraction of α-cellulose from the samples. Cellulose samples were pretreated at AARAMS, and the graphitization and radiocarbon analysis of these samples were done at both AARAMS and the radiocarbon dating laboratory at Lund University to compare the graphitization and AMS machine performance. No significant offset was found between the two sets of measurements. Based on these tests, the pretreatment of tree rings for high-precision radiocarbon analysis at AARAMS will henceforth use HCI for the delignification.



1995 ◽  
Vol 583 ◽  
pp. 263-267 ◽  
Author(s):  
A. Lépine-Szily ◽  
J.M. Casandjian ◽  
W. Mittig ◽  
A.C.C. Villari ◽  
R. Lichtenthäler Filho ◽  
...  


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