Limo develops fast in-line solar cell inspection with asymmetric homogeneous diode laser illumination


Illumination systems for analysing surface properties are often located perpendicular to the inspected surface. Therefore, the solar cell has to be illuminated under a certain angle to improve the signal.

Limo has developed a diode laser that generates photoluminescence and thermographic signals by asymmetric homogeneous illumination of the solar cell. The 120 W fiber-coupled industrial laser system LIMO120-F400-SL808-103 is combined with the processing head IOS00019x-series. This device generates a homogeneously illuminated field under 35° angle of incident that fits to solar cell sizes up to 210 x 210 mm.

The center wavelength of 790…808 nm is essential for the separation of excitation source and signal light. In addition, small bandwidth versions (< 1 nm) are available as an option.

Solar cell inspection tools based on the Limo laser source operate with a single light source compared to other inspection tools using two light sources. That makes the tools more compact and reduces materials as well as assembly costs. A special advantage of an in-line inspection tool: the quality inspection of the solar cells occurs at the full production speed without interrupting the production. Those advantages guarantee high productivity and low cost per tested unit.

Homogeneously illuminated fields create value in metrology applications in a variety of industries, including medicine or chemical analysis. For further information, visit our website or contact Dr. Frank Kubacki ( Please also visit us at the 25th European Photovoltaic Solar Energy: level 2, hall 2, booth A48.