Micro-crack detection in solar cells
The cell is excited in a light-tight optical station and a filtered camera collects its photoluminescence image. Dark linear traces in the image are separated from the cell texture; a cracked cell is placed in a separate tray.
Crack location and decision are linked to the cell record. Line control advances the cell to the station exit; a defective cell is moved to a separate tray by the robot with a vacuum gripper, and the processed image stays on the operator display.
- 01 Infeed
- 02 Excite
- 03 Acquire
- 04 Segment
- 05 Sort
The cell enters the light-tight station and stops.
- Crack trace length
- —
- Suspect traces
- —
Scenes are illustrative simulations; they are not customer references or performance guarantees.
Need
A micro-crack lies inside the silicon and is usually invisible in a reflected-light surface image. In the photoluminescence image, grain boundaries, conductive fingers and stray ambient light produce dark lines that resemble a crack trace.
Solution approach
In a light-tight station the cell is optically excited; a filtered overhead camera blocks the excitation light and images only the emission of the cell. A crack appears as a dark, non-emitting line. Thin connected dark traces are segmented inside the cell mask; regular lines along the finger and busbar directions are rejected, and the length and orientation of the remaining trace are evaluated.
Process steps
- 01
Infeed
The cell enters the light-tight station and stops.
- 02
Excite
The optical source excites the cell and it starts to emit.
- 03
Acquire
The filtered camera collects the photoluminescence image.
- 04
Segment
Dark linear traces are found inside the cell mask.
- 05
Sort
The cell advances to the exit; a cracked one is moved to a separate tray.
Related applications
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