| US 7,541,600 B2 | ||
| Lithographic and measurement techniques using the optical properties of biaxial crystals | ||
| Daniel Neuhauser, Los Angeles, Calif. (US); and Gabriel Y. Sirat, Rehovot (Israel) | ||
| Assigned to The Regents of the University of California, Oakland, Calif. (US) | ||
| Filed on Jul. 14, 2006, as Appl. No. 11/488,176. | ||
| Claims priority of provisional application 60/728448, filed on Oct. 19, 2005. | ||
| Claims priority of provisional application 60/700017, filed on Jul. 15, 2005. | ||
| Prior Publication US 2007/0171432 A1, Jul. 26, 2007 | ||
| Int. Cl. G01J 1/00 (2006.01); G01N 21/00 (2006.01); G01N 23/00 (2006.01) | ||
| U.S. Cl. 250—491.1 [356/614; 356/367; 356/369; 356/364; 356/365; 356/491; 356/330; 356/328; 356/326; 356/348; 356/301; 356/240; 356/281; 359/498; 359/326; 359/316; 372/21; 372/105; 372/106; 372/27; 372/32] | 27 Claims |
| 1. A method for measuring the position of an optical feature, comprising:
directing light associated with the optical feature along an axis of a biaxial crystal;
conically refracting said light to transform the image of said optical feature to comprise a circular ring structure; and
calculating the position of the optical feature by locating a center point associated with the circular ring structure.
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