Method for illuminating a substrate using multiple acousto optical devices

A method for illuminating a substrate, the method comprising:

• generating a plurality of beams of collimated light;
• projecting the plurality of beams of collimated light towards a plurality of acousto-optic devices, wherein each acousto-optic device in the plurality of acousto-optic devices comprises a surface having an illuminated region and a region outside the illuminated region to concurrently illuminate the illuminated regions of the plurality of acousto-optic devices without illuminating the regions outside the illuminated regions while concurrently feeding the acousto-optic devices with control signals, wherein an area of the illuminated region on the surface of each acousto-optic device is less than 30 percent of an area of the surface;
• outputting, concurrently, output illuminated regions output beams from the illuminated regions of the acousto-optic devices, wherein the output illuminated regions are collimated and exhibit deflection angles that scan, during a scan period, a deflection angular range;
• combining, by an optical combining module arranged to receive the illuminated regions output beams from the acousto-optic devices, the illuminated regions output beams to provide combined beams, each combined beam covers a continuous angular range;
• wherein different ones of the combined beams exhibit, at an output plane of the optical combining module, different deflection angles;
• receiving, by a relay module, the combined beams and outputting collimated output beams towards an output aperture and imaging the output plane of the optical combining module onto the output aperture;
• and
• receiving, by an output module, the collimated output beams and converting the collimated output beams to spaced apart spots on the substrate.

A system for illuminating a substrate, the system comprising:

• an illumination source configured to concurrently generate a plurality of beams of collimated light;
• a plurality of acousto-optic devices corresponding in number to the plurality of beams of collimated light, each acousto-optic device in the plurality of acousto-optic devices comprising a surface having an illuminated region and a region surrounding the illuminated region, wherein the illumination source is arranged to project the plurality of beams of collimated light onto the illuminated regions of the plurality of acousto-optic devices without illuminating the regions surrounding the illuminated regions such that the illuminated region of each acousto-optic device receives a different collimated beam of light from the plurality of beams of collimated light, wherein for each acousto-optic device, the illuminated region is less than 30 percent of the surface of the acousto-optic device;
• a controller operatively coupled to send control signals to the plurality of acousto-optic devices to, while the plurality of acousto-optic devices concurrently receive the plurality of beams of collimated light from the illumination source, cause the illuminated regions to concurrently output illuminated region output beams that are collimated and exhibit deflection angles that scan, during a scan period, a deflection angular range;
• an optical combining module arranged to receive the illuminated region output beams from the plurality of acousto-optic devices and configured to combine the illuminated region output beams to provide a plurality of combined beams, wherein each combined beam covers a continuous angular range, and wherein different ones of the plurality of combined beams exhibit, at an output plane of the optical combining module, different deflection angles;
• an output aperture;
• a relay module arranged to receive the plurality of combined beams and configured to output collimated output beams towards the output aperture to image the output plane of the optical combining module onto the output aperture;
• and
• an output module arranged to receive the collimated output beams through the output aperture and configured convert the collimated output beams to spaced apart spots on the substrate.