Stabilization of parallel transport mirror system

A method of beam stabilization for ensuring parallel transport of an orthogonally scanned coherent light beam scanned in an X-direction, a Y-direction to a Z-direction for incidence through a mask for forming images to ablate a workpiece wherein said scanning system includes:

• scanning stages including;
• a first scanning stage with a first right angle reflecting mirror to scan the coherent light beam in the X-direction and reflect the scanned coherent light beam to the Y-direction;
• a second scanning stage with a second right angle reflecting mirror mounted to the first scanning stage to deflect the scanned coherent light beam in the Y-direction and reflect the scanned coherent light beam downward through the mask and onto the workpiece;
• the process comprising the steps of:
• providing a reference beam;
• providing a reference path for the reference beam including;
• a first reference stage with a first reference beam right angle reflecting mirror to scan the reference beam opposite to the X-direction of the scanned coherent light beam and reflect the reference beam opposite to the Y-direction of the scanned coherent light beam;
• a second reference stage with second reference beam right angle reflecting mirror mounted to the first scanning stage to deflect the reference beam opposite to the Y-direction of the scanned coherent light beam and reflect the reference beam upward opposite to the Z-direction of incidence of the scanned coherent light beam through the mask;
• reflecting the reference beam oppositely through the reference path;
• providing a detector having means for sensing reference beam position;
• diverting the reflected reference beam to the detector having means for sensing the reference beam position;
• providing a steerable mirror located before the scanning stages for moving the scanned coherent light beam equal and opposite to the sensed reference beam position at the detector having means for sensing beam position;
• and,
• measuring excursion at the detector having means for sensing beam departure from true parallel transport to produce a signal for driving the steerable mirror in the X-direction and the Y-direction on incidence to the scanning system.

An attached system of beam stabilization for ensuring parallel transport of an orthogonally scanned coherent light beam scanned in an X-direction, a Y-direction to a Z-direction wherein said scanning system includes:

• scanning stages including;
• a first scanning stage with a first right angle reflecting mirror to scan the coherent light beam in the X-direction and reflect the scanned coherent light beam to the Y-direction;
• a second scanning stage with a second right angle reflecting mirror mounted to the first scanning stage to deflect the scanned coherent light beam in the Y-direction and reflect the scanned coherent light beam downward through the mask and onto the workpiece;
• the improvement comprising:
• a reference beam;
• a reference path for the reference beam including;
• a first reference stage with a first reference beam right angle reflecting mirror to scan the reference beam in the X-direction of the scanned coherent light beam and reflect the reference beam in the Y-direction of the scanned coherent light beam;
• a second reference stage with second reference beam right angle reflecting mirror mounted to the first scanning stage to deflect the reference beam in the Y-direction of the scanned coherent light beam and reflect the reference beam in the Z-direction of incidence of the scanned coherent light beam through the mask;
• means for reflecting the reference beam through the reference path;
• a detector having means for sensing reference beam position;
• means for diverting the reflected reference beam to the detector having means for sensing the reference beam position;
• a steerable mirror located before the scanning stages for moving the scanned coherent light beam equal and opposite to the sensed reference beam position at the detector having means for sensing beam position;
• and,
• means for measuring excursion at the detector having means for sensing beam departure from true parallel transport to produce a signal for driving the steerable mirror in the X-direction and the Y-direction on incidence to the scanning system.

A method of beam stabilization for ensuring parallel transport of an orthogonally scanned coherent light beam scanned in an X-direction, a Y-direction to a Z-direction wherein said scanning system includes:

• scanning stages including;
• a first scanning stage with a first right angle reflecting mirror to scan the coherent light beam in the X-direction and reflect the scanned coherent light beam to the Y-direction;
• a second scanning stage with a second right angle reflecting mirror mounted to the first scanning stage to deflect the scanned coherent light beam in the Y-direction and reflect the scanned coherent light beam downward through the mask and onto the workpiece;
• the process comprising the steps of:
• providing a reference beam;
• providing a reference path for the reference beam including;
• a first reference stage with a first reference beam right angle reflecting mirror to scan the reference beam in the X-direction of the scanned coherent light beam and reflect the reference beam in the Y-direction of the scanned coherent light beam;
• a second reference stage with second reference beam right angle reflecting mirror mounted to the first scanning stage to deflect the reference beam in the Y-direction of the scanned coherent light beam and reflect the reference beam in the Z-direction of incidence of the scanned coherent light beam through the mask;
• reflecting the reference beam through the reference path;
• providing a detector having means for sensing reference beam position;
• diverting the reflected reference beam to the detector having means for sensing the reference beam position;
• providing a steerable mirror located before the scanning stages for moving the scanned coherent light beam equal and opposite to the sensed reference beam position at the detector having means for sensing beam position;
• and,
• measuring excursion at the detector having means for sensing beam departure from true parallel transport to produce a signal for driving the steerable mirror in the X-direction and the Y-direction on incidence to the scanning system.