Beam scanning optical system

A beam scanning optical system for providing scanning of a beam receiving surface, comprising:

• emitting means for emitting a light beam;
• converging means for converging the light beam emitted from the emitting means into a straight line;
• deflection means for deflecting the light beam across a field angle, which is provided at a position in the vicinity where the light beam is converged by the converging means, at an equiangular velocity in a scanning direction;
• and
• reflecting means for directing the light beam as deflected by the deflection means in a nonrefracted state to the beam receiving surface, including a toroidal mirror for reflecting the light beam deflected by the deflecting means onto the beam receiving surface so as to linearly move a spot of the light beam substantially at a constant speed on the beam receiving surface, a height of a generatrix of the reflective surface of the toroidal mirror being displaced in a reverse direction to a direction of incidence on the toroidal mirror of the light beam according to an increment of the angle of field.

A beam scanning optical system for providing a scan line of a light beam across a surface, comprising:

• emitting means for emitting a light beam;
• converging means, downstream of the emitting means, for converging the light beam into a substantially straight line;
• deflection means, downstream of the converging means, for deflecting the light beam across a field angle at an equiangular velocity in a scanning direction;
• and
• a toroidal mirror means, positioned downstream of the deflection means for directly receiving the deflected light beam, for reflecting the light beam directly to the surface so as to linearly move the light beam at a constant speed across the surface between both edge positions of the scanning line.