Real-Time Monitoring and Defect Detection of Laser Scribing Process of CIGS Solar Panels Utilizing Photodiodes

Abstract

Laser scribing is developing rapidly in industrial applications as a method of material processing, especially in areas that require high levels of precision. This technology provides functionality and efficiency improvements in the manufacturing of solar panels. Due to the premium quality and speed requirements of the laser scribing technology, monitoring of this process in real-time is critical in order to promptly detect defects in the manufacturing process. However, common monitoring systems have been developed for other laser processes, like laser welding, which are noticeably slower than the laser scribing process. The goal of this research was to investigate the possibility of using photodiodes for real-time monitoring of the laser scribing process for Copper Indium Gallium Selenide (CIGS) solar panels. Various monitoring setup configurations were designed, developed, and examined to determine the viable option for implementation as a defect detection platform. Using different photodiode positions, the intensity of the light and the photodiode induced voltage for diffuse and specular reflections were tested, and the practical pros and cons of applying each configuration were analyzed. The capability of the monitoring system to distinct the different layers of the scribed CIGS cell was also examined to assess the penetration depth of the scribe. In addition, by performing several experiments with different scribe thicknesses and analyzing oscilloscope measurements, the optimal placement of the photodiode for accurate tracing of the scribing path was determined and verified. Key aspects of development of such monitoring system for solar panel applications were identified through this research.

Design and Development of a Multisensory Real-Time Monitoring Platform for Ultrafast Laser Engraving Process

“…Quality of the scribed surface is crucial in the laser scribing process, especially in the fields where precision level significantly affects the efficiency of the finished product [11], [12]. Monitoring the laser scribing process in real-time is an effective solution to improve the quality by realizing the occurring phenomena and detecting the defects online [13], [14], [15]. The purpose of real-time monitoring of the process is to manually correct the defective point if possible or provide the gathered process data to the control system in order to adjust the process parameters, such as increasing or decreasing the laser power, and consequently rectifying the defect online when the scribing process is carrying on.…”

“…The purpose of real-time monitoring of the process is to manually correct the defective point if possible or provide the gathered process data to the control system in order to adjust the process parameters, such as increasing or decreasing the laser power, and consequently rectifying the defect online when the scribing process is carrying on. There are diverse methods for laser process monitoring, the most common of which are optical methods [13], [14], [15], [16]. Optical approach has several advantages over other monitoring methods such as acoustic and electrical methods.…”

“…Optical monitoring methods have a non-contact operation and provide a large amount of data based on the output of spatial or spectral techniques used [14], [16]. Different types of cameras, photodiodes, pyrometers, and spectrometers are examples of optical sensors that can be used for monitoring purpose [15], [17], [18], [19]. It should be noted that thermal methods can be included in the group of optical methods [16], [20].…”