Patent ID: 6187211
Filing Date: 2001-02-13
Classification: G03F

Abstract:
A method of forming a four-phase Fresnel lens for use in acoustic printing, the method comprising steps of:depositing a first layer of a first material comprised of a plurality of compounds supplied in first proportions, the first material being etchable at a first rate;altering the first proportions of the plurality of compounds to obtain a second material comprised of the plurality of compounds supplied in second proportions, the second material being etchable at a second rate less than the first rate;depositing a first layer of the second material on the first layer;altering the second proportions to obtain the first material;depositing a second layer of the first material on the first layer of the second material;altering the first proportions to obtain the second material;depositing a second layer of the second material on the second layer of the first material;altering the second proportions to obtain the first material;depositing a third layer of the first material on the second layer of the second material, the first, second and third layers of the first material and the first and second layers of the second material comprising a block; and,selectively masking and etching the block to form the lens.