US 5,837,962 A · Faster laser marker employing acousto-optic deflection

Abstract

By adding an acousto-optic deflector to an existing design of laser marker the laser marker's throughput is increased by a large factor, typically a factor of 5. Galvanometer driven mirrors, which in existing laser markers are used to trace out the strokes in characters are, in this invention, used only to scan smoothly along lines of characters. The acousto-optic deflector, being much faster than the galvanometers, is used to trace out the individual strokes in the characters. Marking rates of 1000 characters per second are achieved in the case of characters for which capital letters are 2 millimeters high and a 2 millimeter long stroke contains 13 laser-produced craters. This performance is achieved over fields as large as 300 millimeters square. The quality of marked characters is improved because the deleterious effects of mirror inertia on character quality, commonly seen when a laser marker is pushed for speed, are eliminated.

Claims28

Dependent claims

An improved apparatus for heating, melting, vaporizing, or cutting a workpiece, of the type which comprises:

a laser generating a laser beam possessing sufficient energy per pulse to accomplish heating, melting, vaporizing or cutting of said workpiece;
a moveable mirror assembly for deflecting said laser beam over said workpiece interposed in the laser beam following said laser;
a lens focusing said laser beam on said workpiece, said lens interposed in the laser beam either before or after said moveable mirror assembly;
and
a controller controlling said moveable mirror assembly and said laser;
wherein the improvement comprises:
(a) a high diffraction efficiency two-dimensional acousto-optic deflector interposed in said laser beam following said laser and having an angular range of deflection smaller than that of said moveable mirror assembly, said two-dimensional acousto-optic deflector comprising
first and second one dimensional acousto-optic deflectors arranged in series and oriented at substantially right angles to one another, and
anamorphic optical elements which substantially focus said two-dimensional acousto-optic deflector on said moveable mirror assembly;
(b) an absorber absorbing that fraction of laser light which is not diffracted by said two-dimensional acousto-optic deflector;
and
(c) a deflector controller controlling a deflection by said two-dimensional acousto-optic deflector, such that the laser beam can be moved over a small angular range more rapidly than said moveable mirror assembly alone would permit, and over a larger angular range than said two-dimensional acousto-optic deflector alone would permit.

9 more elements

An improved apparatus for heating, melting, vaporizing, or cutting a workpiece, of the type which comprises:

a laser generating a laser beam possessing sufficient energy per pulse to accomplish heating, melting, vaporizing or cutting of said workpiece;
a moveable mirror assembly for deflecting said laser beam over said workpiece interposed in the laser beam following said laser;
a lens focusing said laser beam on said workpiece, said lens interposed in the laser beam either before or after said moveable mirror assembly;
and
a controller controlling said moveable mirror assembly and said laser;
wherein the improvement comprises:
(a) a high diffraction efficiency two-dimensional acousto-optic deflector interposed in said laser beam following said laser and having an angular range of deflection smaller than that of said moveable mirror assembly, said two-dimensional acousto-optic deflector comprises
first and second one dimensional acousto-optic deflectors arranged in series and oriented at substantially right angles to one another, and
anamorphic optical elements which substantially focus said first one-dimensional acousto-optic deflector on said second one-dimensional acousto-optic deflector, and focus said second one-dimensional acousto-optic deflector on said moveable mirror assembly, said anamorphic optical elements are located between said first and second one-dimensional acousto-optic deflectors and comprise additional lenses for forming a real image of the laser, said real image being also located between the first and second said one-dimensional acousto-optic deflectors;
(b) an absorber absorbing that fraction of laser light which is not diffracted by said two-dimensional acousto-optic deflector, said absorber comprises a second mirror assembly interposed in an optical path near said real image, offset from a center line of the optical path so that it intercepts, and therefore eliminates, undiffracted light from said first one-dimensional acousto-optic deflector, but allows diffracted light to pass on to said second one-dimensional acousto-optic deflector;
and
(c) a deflector controller controlling a deflection by said two-dimensional acousto-optic deflector, such that the laser beam can be moved over a small angular range more rapidly than said moveable mirror assembly alone would permit, and over a larger angular range than said two-dimensional acousto-optic deflector alone would permit.

9 more elements

An improved apparatus for heating, melting, vaporizing, or cutting a workpiece, of the type which comprises:

a laser generating a laser beam possessing sufficient energy per pulse to accomplish heating, melting, vaporizing or cutting of said workpiece;
a moveable mirror assembly for deflecting said laser beam over said workpiece interposed in the laser beam following said laser;
a lens focusing said laser beam on said workpiece, said lens interposed in the laser beam either before or after said moveable mirror assembly;
and
a controller controlling said moveable mirror assembly and said laser;
wherein the improvement comprises:
(a) a high diffraction efficiency two-dimensional acousto-optic deflector interposed in said laser beam following said laser and having an angular range of deflection smaller than that of said moveable mirror assembly;
(b) an absorber absorbing that fraction of laser light which is not diffracted by said two-dimensional acousto-optic deflector;
and
(c) a deflector controller controlling a deflection by said two-dimensional acousto-optic deflector, such that the laser beam can be moved over a small angular range more rapidly than said moveable mirror assembly alone would permit, and over a larger angular range than said two-dimensional acousto-optic deflector alone would permit, said deflector controller comprising
electronics for generating and controlling frequencies and power levels provided to said two-dimensional acousto-optic deflector;
and
a computer which generates sequences of control signals for said electronics, and provides real time control for:
decomposing a desired laser beam direction into x and y components due to said moveable mirror assembly and x and y components due to said two-dimensional acousto-optic deflector,
compensating for the fact that said moveable mirror assembly does not respond immediately to its controlling signals, and
compensating for distortion by said lens, nonlinearities of actuators or sensors of said moveable mirror assembly, non-orthogonality of deflector and mirror axes, and inherent pincushion distortion that occurs when two moveable mirrors are used.

13 more elements

An improved laser marker, of the type which comprises:

a laser producing a laser beam possessing sufficient energy per pulse to accomplish marking of a workpiece;
a moveable mirror assembly for deflecting said laser beam over said workpiece interposed in the laser beam following said laser;
a lens focusing said laser beam on said workpiece, said lens interposed in the laser beam either before or after said moveable mirror assembly;
and
a controller controlling said moveable mirror assembly and said laser;
wherein the improvement comprises:
(a) a high diffraction efficiency two-dimensional acousto-optic deflector interposed in said laser beam following said laser and having an angular range of deflection smaller than that of said moveable mirror assembly, said two-dimensional acousto-optic deflector comprising
first and second one dimensional acousto-optic deflectors arranged in series and oriented at substantially right angles to one another, and
anamorphic optical elements which substantially focus said two-dimensional acousto-optic deflector on said moveable mirror assembly;
(b) an absorber absorbing that fraction of laser light which is not diffracted by said two-dimensional acousto-optic deflector;
and
(c) a deflector controller controlling a deflection by said two-dimensional acousto-optic deflector, such that the laser beam can be moved over a small angular range more rapidly than said moveable mirror assembly alone would permit, and over a larger angular range than said two-dimensional acousto-optic deflector alone would permit.

9 more elements

An improved laser marker, of the type which comprises:

a laser producing a laser beam possessing sufficient energy per pulse to accomplish marking of a workpiece;
a moveable mirror assembly for deflecting said laser beam over said workpiece interposed in the laser beam following said laser;
a lens focusing said laser beam on said workpiece, said lens interposed in the laser beam either before or after said moveable mirror assembly;
and
a controller controlling said moveable mirror assembly and said laser;
wherein the improvement comprises:
(a) a high diffraction efficiency two-dimensional acousto-optic deflector interposed in said laser beam following said laser and having an angular range of deflection smaller than that of said moveable mirror assembly, said two-dimensional acousto-optic deflector comprises
first and second one dimensional acousto-optic deflectors arranged in series and oriented at substantially right angles to one another, and
anamorphic optical elements which substantially focus said first one-dimensional acousto-optic deflector on said second one-dimensional acousto-optic deflector, and focus said second one-dimensional acousto-optic deflector on said moveable mirror assembly, said anamorphic optical elements are located between said first and second one-dimensional acousto-optic deflectors and comprise lenses for forming a real image of the laser, said real image being also located between the first and second said one-dimensional acousto-optic deflectors;
(b) an absorber absorbing that fraction of laser light which is not diffracted by said two-dimensional acousto-optic deflector, said absorber comprising a mirror assembly interposed in an optical path near said real image, offset from a center line of the optical path so that it intercepts and eliminates undiffracted light from said first one-dimensional acousto-optic deflector, and allows diffracted light to pass on to said second one-dimensional acousto-optic deflector;
and
(c) a deflector controller controlling a deflection by said two-dimensional acousto-optic deflector, such that the laser beam can be moved over a small angular range more rapidly than said moveable mirror assembly alone would permit, and over a larger angular range than said two-dimensional acousto-optic deflector alone would permit.

9 more elements

An improved laser marker, of the type which comprises:

a laser producing a laser beam possessing sufficient energy per pulse to accomplish marking of a workpiece;
a moveable mirror assembly for deflecting said laser beam over said workpiece interposed in the laser beam following said laser;
a lens focusing said laser beam on said workpiece, said lens interposed in the laser beam either before or after said moveable mirror assembly;
and
a controller controlling said moveable mirror assembly and said laser;
wherein the improvement comprises:
(a) a high diffraction efficiency two-dimensional acousto-optic deflector interposed in said laser beam following said laser and having an angular range of deflection smaller than that of said moveable mirror assembly;
(b) an absorber absorbing that fraction of laser light which is not diffracted by said two-dimensional acousto-optic deflector;
and
(c) a deflector controller controlling a deflection by said two-dimensional acousto-optic deflector, such that the laser beam can be moved over a small angular range more rapidly than said moveable mirror assembly alone would permit, and over a larger angular range than said two-dimensional acousto-optic deflector alone would permit, said deflector controller comprising
electronics for generating and controlling frequencies and power levels provided to said two-dimensional acousto-optic deflector;
a computer which generates sequences of control signals for said electronics, and provides real time control for:
decomposing a desired laser beam direction into x and y components due to said moveable mirror assembly and x and y components due to said two-dimensional acousto-optic deflector,
compensating for the fact that said moveable mirror assembly does not respond immediately to its controlling signals, and
compensating for distortion by said lens, nonlinearities of actuators or sensors of said moveable mirror assembly, non-orthogonality of deflector and mirror axes, and inherent pincushion distortion that occurs when two moveable mirrors are used.

12 more elements

Dependencies are inferred from the claim text.

Faster laser marker employing acousto-optic deflection

Life of this patent

Faster laser marker employing acousto-optic deflection

Life of this patent

Abstract

Claims28