Design of a microcontroller based testing system for electrodes of light-sources

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Oláh István
Department of Automation and Applied Informatics

The subject of my thesis is the development of a microcontroller based measurement system that is capable of testing the electrodes of light sources in order to determine their quality and parameters. This is a remarkably complex task, since the system has to accurately measure several parameters, while working as a control system to simulate the actual fabrication process of light sources. The system has to be fast, as well as accurate to successfully accomplish this task.

The testing system in question substitutes several components in an existing measurement setup. Firstly, the system is a finely adjustable and programmable laboratory power supply with current and voltage limit. As such, it substitutes an Agilent E3649A DC Power Supply in the existing setup. It also acts as a data acquisition system (DAQ) as it is capable of measuring the voltage drop across the cathode, the current that passes through it and the emission current leaving it, replacing three multimeters. The system also performs 4-wire resistance measurement, replacing a Keithley 2400 Series SourceMeter. The system also provides complete galvanic isolation. It also possesses a number of analog and digital inputs/outputs, giving the possibility of controlling other parts of the testing configuration (such as the flow of argon gas into the vacuum chamber by shutting or opening a valve), or the extension of its features. This ensures the accurate simulation of the manufacturing process and the making of more precise measurements.

Since my thesis is the continuation of my Project Laboratory, I already had a finished schematic of the measurement system, as well as a partially complete PCB design. As a result, I endeavored to finish the project this semester. To accomplish this, I first completed the PCB design (this mostly consisted of routing the PCB), and once the PCB was available, installed the electrical components and made sure that they are in operating condition. Once these steps were done, I developed an application that allows the user to easily and efficiently control the measurement process (this necessitated the use of a graphical user interface).


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