US Patent 7253936 Laser scanning unit

A laser scanning unit is provided which can use an inexpensive and easily manufactured fθ lens and which can further ensure good precision in adjustment. The laser scanning unit can repeatedly scan focused light onto a scan line, and includes a multi-beam light source for emitting parallel light, first and second cylindrical lenses for focusing the parallel light in a sub-scanning direction and a main scanning direction, respectively, a polygon mirror for deflecting the focused light in the main scanning direction, and an fθ lens for focusing the deflected light on the scan line.