Two-dimensional scanning device having compensation for scanned image strain

A two-dimensional scanning device comprising:

• a light source portion for supplying a collimated beam;
• a first deflector for deflecting the collimated beam from said light source portion and effecting major scanning on a scanned surface;
• a second deflector for deflecting the light beam deflected by said first deflector in a plane perpendicular to the deflection plane of the light beam deflected by said first deflector and effecting minor scanning on said scanned surface;
• an image forming optical system disposed between said first deflector and said second deflector for condensing the scanning beam onto said scanned surface;
• means for moving said image forming optical system in the direction of its optic axis in synchronism with the deflecting action of said second deflector;
• first detector means for detecting the position of the deflection plane of said first deflector;
• second detector means for detecting the position of the deflection plane of said second deflector;
• and
• circuit means for controlling the starting and stopping of the modulation of the scanning beam in accordance with the signals from said first and second detector means.

A two-dimensional scanning device for scanning a stationary surface, comprising:

• means for providing a light beam;
• primary deflector means for deflecting said light beam to effect scanning on the stationary surface in one direction, and for deflecting light reflected from said stationary surface;
• secondary deflector means for effecting scanning of said light beam on the stationary surface in a direction orthogonal to said one direction and for receiving the reflected light deflected by said primary deflector means and deflecting the reflected light in a direction orthogonal to the direction of deflection of the light beam by said primary deflector means;
• light detecting means for detecting the reflected light deflected from said secondary deflector means;
• an image forming optical system disposed between said primary deflector means and said secondary deflector means;
• and
• mechanical means for varying the spacing between said image forming optical system and said primary deflector means in synchronism with the deflecting action of said primary deflector means.

A two-dimensional scanning device comprising:

• means for supplying a light beam;
• first deflector means for deflecting said light beam to effect major scanning on a surface to be scanned;
• second deflector means for deflecting a light beam in a direction orthogonal to the direction of deflection of the light beam by said first deflector means to effect minor scanning on the surface in a direction orthogonal to said major scanning:
• an image forming optical system disposed between said first deflector means and said second deflector means;
• mechanical means for varying the spacing between said image forming optical system and said second deflector means in synchronism with the deflecting action of said second deflector means;
• light dividing means disposed between said light supplying means and said first deflector means;
• and
• light receiving means for receiving the light beam from the surface by way of said second deflector, said image forming optical system, said first deflector means and said light dividing means in the order named.