Machine vision technique for manufacturing semiconductor wafers

A vision system for determining a positional relationship between a photovoltaic device wafer and a printing element, wherein the photovoltaic device wafer is on a platen that has an aperture there through and the printing element is located on a remote side of the photovoltaic device wafer from the platen, the vision system comprises:

• a source which emits ultraviolet light along a path that is transverse to a longitudinal axis of the aperture;
• a diffuser panel located along the path of the light from the source;
• a reflector for directing the light from the diffuser panel toward the aperture;
• and
• a camera located along the longitudinal axis of the aperture in the platen and producing an electrical image using light received from the aperture, wherein some of the received light was reflected by the photovoltaic device wafer and some of the received light was reflected by the printing element.

A method for determining a positional relationship between a photovoltaic device wafer on a platen and a printing element on a remote side of the photovoltaic device wafer from the platen, said method comprising:

• emitting ultraviolet light from a source, wherein the light travels along a path that is transverse to a longitudinal axis of the aperture;
• directing the ultraviolet light from the source through a diffuser assembly;
• reflecting the ultraviolet light from the diffuser assembly into an aperture in the platen, and toward the photovoltaic device wafer;
• and
• producing an electrical image from light exiting the aperture in the platen, wherein some of the received light was reflected by the photovoltaic device wafer and some of the received light was reflected by the printing element.