Ultra-high-speed laser printers have been used for production printing, and have recently been extended to ondemand printing where higher resolution printing with an offset press is required. Therefore, developing an optical scanning system that provides a higher scanning rate is necessary. A 20-channel edge emitting laser diode array emits high output power for the purpose of increasing the scanning rate. As the beams for scanning increase, their positional errors become critical. Therefore, higher resolution lenses, which are stable against thermal variation, are also required for the system.An example of an optical scanning system using 20-channel edge emitting laser diode array and some optical techniques for higher resolution are introduced.