Image reproduction system including a cooling unit for cooling light emitting units and method for using system

A method for controlling an image reproduction system comprising at least a first light emitting unit and a second light emitting unit, said first light emitting unit having a first elongate light emitting area;

• said second light emitting unit having a second elongate light emitting area;
• said method comprising:
• actively cooling said first light emitting unit;
• actively cooling said second light emitting unit independently of said first light emitting unit;
• controlling at least one of actively cooling said first light emitting unit and actively cooling said second light emitting unit, such that, when the first and second light emitting units have a different length at a same temperature, the first and second light emitting units are controlled to be at different temperatures, leading to a different expansion thereof which is controlled such that the lengths thereof are substantially equal.

A system for use in image reproduction, said system comprising:

• at least a first light emitting unit and a second light emitting unit;
• said first light emitting unit comprising a first cooling means arranged for cooling said first light emitting unit;
• said second light emitting unit comprising a second cooling means arranged for cooling said second light emitting unit independently of said first light emitting unit;
• said first light emitting unit having a first elongate emitting area;
• said second light emitting unit having a second elongate emitting area;
• a measurement device configured for measuring at least one measure representative of a difference between a first and second length of the first and second elongate light emitting area, respectively;
• a control unit configured for controlling the cooling of at least one of said first cooling means and said second cooling means based on said at least one measure;
• wherein said measurement device comprises any one of the following:
• a camera, an optical density sensor, an interference pattern measurement device, a spectrograph measurement device.