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

Abstract

Introduction. When operating high-precision measurement setups, the reliability of measurements needs to be guaranteed. The displacement of elements from the measurement path can lead to a distortion of measurement results, especially in measurement setups operating in the microwave range. In order to ensure measurement reliability, the positions of elements in the measurement setup needs to be monitored. The monitoring should be performed during the measurement. The control device, which should be connected to the automatic control system of the measurement setup, should neither mechanically affect the setup elements nor introduce any interference. Currently used control systems for the technical characteristics do not meet the necessary requirements.Objective. To design a control system which allows for the monitoring of displacements of elements in a high precision measuring setup with an accuracy of 1.0 · 10 4 mm and digital signal processing. The control system thus designed should neither mechanically affect the controlled elements nor introduce electrical and electromagnetic interferences.Materials and methods. The system thus designed utilises optical methods for displacement monitoring based on the principles of geometric optics. Mathematical modelling (Mathcad) methods were used to determine the reaction of the system to changes in the beam trajectory and to estimate the sensitivity of the optical control system. Charge-coupled devices (CCD) were used to record the system response to optical path changes.Results. The study presents two designs of a control system for the displacement monitoring of high precision measurement setup elements. The first system design allows for the detection of the occurrence of displacement, while the second system design allows for the identification of the displaced element. The system is capable of registering displacements of elements up to an accuracy of 1.0 · 10 4 mm and monitoring the position of elements while exposed to vibration. The system does not mechanically or electromagnetically affect the controlled elements. All system elements are resistant to microwave radiation and increased background radiation, excluding the CCD which needs to be placed outside the active zone. The monitoring system for movements of elements in the high-precision measuring setup allows for digital signal processing. The study proposes a method to increase system accuracy.Conclusion. The system can be used in setups with increased microwave, x-ray and radiation emission. In comparison with systems based on other physical principles (inductive, capacitive and rheostat), the system thus developed is much easier to implement.

Keywords

• displacement control
• structural integrity control
• optical control system
• measurement setup