Deflection scanning optical system with reflecting sections

A deflection scanning optical system comprising:

• a laser beam source emitting a laser beam toward a surface to be scanned;
• a single first mirror arranged between said laser beam source and said surface to be scanned, said first mirror having a first reflecting section, a second reflecting section and a transparent section, the laser beam from said laser beam source being reflected by said first reflecting section;
• a second mirror for reflecting the laser beam reflected by said first reflecting section of said first mirror, toward said second reflecting section of said first mirror, said second mirror also reflecting the laser beam reflected by said first reflecting section of said first mirror to transmit the reflected laser beam through said transparent section of said first mirror, thereby directing the transmitted laser beam toward said surface to be scanned;
• and
• detecting means receiving the laser beam reflected by said second mirror toward said second reflecting section of said first mirror and reflected by said second reflecting section, for detecting a scanning position of the laser beam with respect to said surface to be scanned.