Metrology + Intelligence = Modern Machine Vision

SolarCheck - MoviTHERM's Lockin Thermography Inspection system specifically designed for shunt detection and NIR emission analysis in photovoltaic cells and panels has been included in an article written by Winn Hardin, Contributing Editor for the Automated Imaging Association. (AIA)

Tarin’s SolarCheck system uses a different, thermal lock-in approach to find very small defects on solar panels at high speeds.  The solar panels are either optically or electrically excited, causing the active areas to generate a faint optical signal as well as a thermal signal.  “In addition to performing an emission analysis, where we excite the cell and measure the inherent near infrared emission between 0.9 and 1.7 microns, we can also perform a shunt detection using a thermal camera with a detector that is sensitive either in the midwave IR (MWIR) region from 3µm to 5µm or in the longwave IR (LWIR) region from 8µm to 14µm. Rather than using a silicon camera without a NIR filter, we use an InGaAs detector with higher sensitivity in the NIR.  Our system can perform lock-in measurements independent of the camera connected to it.  Using a Lock-in technique enables our system to extract signals below the noise floor of the camera.  The concept is based on the random distribution of noise combined with a known excitation signal with respect to its frequency and phase relation.  A very steep band pass filter matched to the frequency of the excitation signal assures that the system only amplifies signals matching that frequency, therefore cancelling out noise.  A fast-Fourier Transform then extracts phase and amplitude information from the signal. The larger the phase shift, the more contrast we assign to the pixel.  Mapping the pixel-by-pixel generated phase information to the amplitude image allows the spatial location of defects, such as shunts.”

>> Read the full article on the AIA website.