| 摘要 |
An adjustable focus lens unit with at least two lens elements and mechanism to adjust the position of at least one of the two lens elements relative to the other in a direction generally perpendicular to a viewing direction. The first of the two lenses has a specially designed surface and the second of the two lenses has a surface that is substantially complementary to the surface of the first lens. In preferred embodiments the lens units are mounted in a frame to provide eyeglasses with adjustable focus. The designs of the specially designed surfaces are chosen such that small adjustments of the relative positions of the two lenses in directions predominantly perpendicular to the viewing direction results in changes in the combined focus of the two lenses of each lens unit. In a preferred embodiment the specially designed surface of the first lens of each lens unit is described by: <?in-line-formulae description="In-line Formulae" end="lead"?>Z(X,Y)=C<SUB>1</SUB>*(X<SUP>3</SUP>/3 +XY<SUP>2</SUP>)+C<SUB>2</SUB>, <?in-line-formulae description="In-line Formulae" end="tail"?> where C<SUB>1 </SUB>and C<SUB>2 </SUB>are constants. And the specially designed surface of the second lens of each lens unit is described by: <?in-line-formulae description="In-line Formulae" end="lead"?>Z<SUB>c</SUB>(X,Y)=-C<SUB>1</SUB>*(X<SUP>3</SUP>/3+XY<SUP>2</SUP>)+C<SUB>2</SUB>. <?in-line-formulae description="In-line Formulae" end="tail"?>
|
