[ii] Patent Number: 5,233,174  Date of Patent: Aug. 3, 1993
 WAVEFRONT SENSOR HAVING A LENSLET ARRAY AS A NULL CORRECTOR
 Inventor: William Zmek, Naugatuck, Conn.
 Assignee: Hughes Danbury Optical Systems, Inc., Danbury, Conn.
 Appl. No.: 849,569
 Filed: Mar. 11,1992
 Int. CI.' G01J 1/20
 U.S. CI 250/201.9; 356/121
 Field of Search ;. 250/201.9, 208.5;
356/121, 124, 125
 References Cited
U.S. PATENT DOCUMENTS
H615 4/1989 Feinleib et al 250/201.9
3,547,546 12/1970 Schier 350/162
4,141,652 2/1979 Feinleib 250/201.9
4,518,854 5/1985 Hutchin 250/201.9
4,530,736 7/1985 Mutter 156/643
A wavefront sensor (10) includes a radiation sensor (2) and an array (12) of lenslets (12A) that are optically coupled to the radiation sensor. The array of lenslets has a radiation receiving surface for receiving an incident wavefront and for focussing the wavefront at a plurality of focal positions upon the radiation sensor. Each of the lenslets comprises a diffractive optical element having an optical center that is located at a predetermined point for inducing an equal and opposite tilt to a portion of the wavefront incident on the lenslet. As a result, an aberration within that portion of the wavefront is cancelled. The predetermined point is determined to be equal to and opposite a focal spot shift of the lenslet.
15 Claims, 3 Drawing Sheets