Device for correcting the shape of an object by laser treatment
First Claim
1. Device for shaping the shape of an object by laser ablation of a surface of said object according to an ablation function A (X,Y), where said object has dimensions in X and Y directions, said X and Y directions are orthogonal directions, values of X and Y are less than the dimension of said object in said X and Y directions, that is to say the thickness to be removed at point of X, Y coordinates on reference axes OX, OY of said surface, O being the center of said object, said ablation function being written as:
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space="preserve" listing-type="equation">A (X,Y)=A.sub.X (X)+A.sub.Y (Y)where AX (X) and AY (Y) represent the respective ablation functions on said reference axes OX and OY, said device comprising;
means for generating a pulses laser beam having pulses and a stable energy density;
means for assuring homogeneity of said energy density;
first slit means for limiting laser radiation passing therethrough, said slit means having at least one slit oriented in the X direction and intercepting said laser beam, said slit having a profile function E (X) given by;
##EQU39## where Δ
XY is a non-zero translation displacement increment in the Y direction and a (e) represents the average thickness removed by irradiation of each laser pulse;
second slit means for limiting laser radiation passing therethrough, said slit means having at least one slit oriented in the Y direction and intercepting said laser beam, said slit having a profile function E (Y) given by;
##EQU40## where Δ
YX is a non-zero translation displacement increment in the X direction;
means for forming an image of said slits onto an area of said surface of said object;
means for displacing said image of said first slit means slit over said area in the Y direction by steps of increment Δ
XY, corresponding to elementary discrete ablations of said surface of said object;
means for displacing said image of said second slit means slit over said area in the X direction by steps of increment Δ
YX, corresponding to elementary discrete ablations of said surface of said object; and
means for synchronizing said increments, said pulses and said energy density, so that the total ablation resulting from the summation of said elementary discrete ablations meets said ablation function A (X,Y).
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Abstract
The invention concerns a device for correcting the shape of an object by laser treatment.
The device comprises means (1) for emitting a laser beam (FL) and means (2) for generating a treatment laser beam (FLT) comprising at least one lobe of elongate cross-section. Means (3) enable focussing of the image of the lobe or lobes of the treatment laser beam on the area of the object (OE) to be corrected and means (4) enable displacement of the image of the lobe of the treatment laser beam in translation or in rotation over the area of the object to be corrected. The total correction or ablation is effected by the summation of a plurality of elementary discrete ablations.
Application to refractive surgery in the case of keratomileusis for myopia, hypermetropia or astigmatism, and to shaping contact lenses and intra-ocular implants.
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Citations
15 Claims
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1. Device for shaping the shape of an object by laser ablation of a surface of said object according to an ablation function A (X,Y), where said object has dimensions in X and Y directions, said X and Y directions are orthogonal directions, values of X and Y are less than the dimension of said object in said X and Y directions, that is to say the thickness to be removed at point of X, Y coordinates on reference axes OX, OY of said surface, O being the center of said object, said ablation function being written as:
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space="preserve" listing-type="equation">A (X,Y)=A.sub.X (X)+A.sub.Y (Y)where AX (X) and AY (Y) represent the respective ablation functions on said reference axes OX and OY, said device comprising; means for generating a pulses laser beam having pulses and a stable energy density; means for assuring homogeneity of said energy density; first slit means for limiting laser radiation passing therethrough, said slit means having at least one slit oriented in the X direction and intercepting said laser beam, said slit having a profile function E (X) given by;
##EQU39## where Δ
XY is a non-zero translation displacement increment in the Y direction and a (e) represents the average thickness removed by irradiation of each laser pulse;second slit means for limiting laser radiation passing therethrough, said slit means having at least one slit oriented in the Y direction and intercepting said laser beam, said slit having a profile function E (Y) given by;
##EQU40## where Δ
YX is a non-zero translation displacement increment in the X direction;means for forming an image of said slits onto an area of said surface of said object; means for displacing said image of said first slit means slit over said area in the Y direction by steps of increment Δ
XY, corresponding to elementary discrete ablations of said surface of said object;means for displacing said image of said second slit means slit over said area in the X direction by steps of increment Δ
YX, corresponding to elementary discrete ablations of said surface of said object; andmeans for synchronizing said increments, said pulses and said energy density, so that the total ablation resulting from the summation of said elementary discrete ablations meets said ablation function A (X,Y). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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Specification