Wavefront characterization and correction

A method for determining at least some of the characteristics of the wavefront of a beam without the need for an artificially generated reference and, using such determined characteristics, to at least partially reshape such wavefront, the method including the steps of:

• a. positioning a curvature sampling device that generates outputs in the path of the beam;
• b. positioning a wavefront reshaping device that includes controls responsive to inputs in the path of the beam;
• c. connecting the curvature sampling device to the wavefront reshaping device via a means for proportioning the outputs to the inputs;
• d. sampling the curvature of the wavefront with the curvature sampling device and generating outputs representative of the curvature of the wavefront;
• e. sending the generated outputs to the proportioning means;
• f. proportioning the outputs from the curvature sampling device to match the inputs needed to drive the controls of the wavefront reshaping device;
• and
• g. sending the proportioned outputs to the wavefront reshaping device to change the shape of the wavefront reshaping device and, hence, the wavefront.

Apparatus for determining at least some of the characteristics of the wavefront of a beam, without the use of an artificially generated reference, and using the determined characteristics to at least partially reshape the wavefront, the apparatus including:

• a. means, positioned in the path of the beam, for at least partially reshaping the wavefront;
• b. a wavefront sensor also positioned along the beam path for determining at least some of the characteristics of the wavefront from features present in the beam itself, the wavefront sensor including a distorted grating and an associated detector, the distorted grating producing at least first and second images of the wavefront, the detector collecting such images producing an output from such images;
• and
• c. means, connected to the detector and to the wavefront reshaping means, for determining from the distorted grating images and without the use of an artificially generated reference the output necessary to adjust the wavefront reshaping means to at least partially reshape the wavefront.

A method for at least partially altering the shape of a wavefront without the use of an artificially generated reference, the method including the steps of:

• a. providing a beam of radiation, the beam having a wavefront;
• b. determining at least some of the characteristics of the wavefront from features present in the beam itself without the need to mathematically recreate the wavefront:
• and
• c. utilizing the determined characteristics to at least partially alter the shape of the wavefront.