JPS62231921A - Laser beam processing optical device - Google Patents

Abstract

PURPOSE:To realize higher accuracy and lower cost by a ftheta lens system by installing a condenser lens in the optical path between a laser beam source and a beam positioner and controlling the position of the condenser lens in the optical-axis direction so that the length of the optical path between the condenser lens and an irradiated position is constant without reference to the irradiated position. CONSTITUTION:The arithmetic circuit 13a in an arithmetic and driving part 7 computes the quantity DELTAL of variation in optical path length L from specifying signals of irradiated positions (x) and (y) supplied from a control part 6 and outputs a control signal for a voice coil type linear motor 4 from a driving circuit 13b. The voice coil type linear motor 4 moves the condenser lens 3 forth by DELTAL in the optical-axis direction to cancel an increase or decrease in optical path length due to deflection. Thus, the position of the condenser lens 3 in the optical-axis direction is so controlled that the optical path lens L is constant and almost equal to the focal length of the condenser lens without reference to the angle of invariably constant without reference to the irradiated positions no a workpiece and uniform and high-accuracy processing a enabled.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a laser processing optical device used as a laser trimming or laser marking device.

Conventional technology In laser processing optical equipment used as laser trimming or laser marking equipment, a deflector called a beam positioner is installed between the laser light source and the non-workpiece to determine the irradiation position on the non-workpiece. Scanning is performed by deflection based on the designated irradiation position designation signal. A galvanometer type beam positioner is commonly used as such a beam positioner.

In such a processing optical device, a converging lens is usually placed between the beam positioner and the object to be processed. In order to achieve linear scanning while ensuring a uniform spot diameter for light rays whose incident position and angle change due to deflection, such converging lenses have a strong barrel distortion called an f-theta lens. A special lens is used.

Problems to be Solved by the Invention The special fθ used in the above conventional laser processing optical device
Since the lens is installed after the beam positioner, it requires a large effective aperture to converge the deflected beam over a wide range, and its structure is extremely complex and expensive in order to achieve a uniform spot diameter and linear scanning. becomes. Further, there is a problem in that distortion peculiar to the fθ lens occurs, and deviation from linear scanning occurs in the peripheral area of scanning.

Structure of the Invention Means for Solving the Problems The laser processing optical device of the present invention which solves the problems of the prior art described above includes a convergent lens installed in the optical path between the laser light source and the beam positioner, and a convergent lens that is installed in the optical path between the laser light source and the beam positioner. A drive unit for displacing in the optical axis direction and a beam positioner are controlled based on an irradiation position designation signal, and the drive device is controlled so that the optical path length between the designated irradiation position and the converging lens is a constant value. The control unit is configured to enable high-precision processing without using a complicated and expensive fθ lens.

Hereinafter, the operation of the present invention will be explained in detail together with examples.

Embodiment FIG. 1 is a block diagram showing the configuration of a laser processing optical device according to an embodiment of the present invention, where l is Nd:YAGlz-f.
Head, 2 is a beam expander, 3 is a converging lens, 4
5 is a voice coil type linear motor, 5 is a galvanometer type beam positioner, 6 is a control section, and 7 is a calculation/drive section. The galvanometer type beam positioner 5 includes X-axis and Y-axis galvanometers 8a and 9a that receive deflection angle designation signals ex and ey outputted from the calculation unit 7, and an X-axis and Y-axis deflection mirror 8 that is rotated by these galvanometers.
b, 9b.

As shown in FIG. 2, the calculation/driving unit 7 transmits a signal specifying the irradiation position (x, y) of the laser oscillation light in the workpiece plane received from the control unit 6 to the X-axis and Y-axis deflection mirror Bb.
, gb into rotation angles (θX, θy)
a, 12b, and an X-axis and Y-axis galvanometer 8a based on these calculation results.

The drive circuit 9a includes drive circuits 11b and Bb that drive the drive circuit 9a. Further, the calculation/driving unit 7 performs a calculation to calculate the amount of change in the optical path length between the converging lens 3 and the irradiation position on the workpiece from the designation signal of the irradiation position (x, y) received from the control unit 6. circuit 1
3a, and a linear motor drive circuit 13b that drives the voice coil type linear motor 3 based on the calculation result.

Nd controlled by control unit 6: YAG laser head 1
The laser beam emitted from the beam expander 2
The beam is magnified by the converging lens 3, and deflected according to the rotation angles of the X-axis and Y-axis deflection mirrors 8a and 3b, while being irradiated onto the workpiece S to perform processing.

Here, the rotation angle of the X-axis deflection mirror 8b is θx1, the rotation angle of the Y-axis deflection mirror 9b is θy, the shortest distance between the converging lens 3 and the X-axis deflection mirror 8b is Ll, and the rotation angle of the X-axis deflection mirror 8b and the Y-axis deflection mirror 9b is Take the shortest distance, , Y-axis deflection mirror 9
If the shortest distance between b and workpiece S is denoted by
1) y=L3tan θy ・ ・
・(2) becomes.

Since the rotation angle of the galvanometer is practically about 100 or less, the approximation error can be kept to about 1/10,000 by approximating a polynomial expansion of about 3rd order. Therefore, in the arithmetic circuits 11a and 12a of the arithmetic/arithmetic drive section 7, from the designation signal of the irradiation position (x, y) supplied from the control section 6, θx = tan -' (x/(Lx
+L3 ) )'4 (X/(L, +L, )
) −N/3)(x/ (t, z +L3))”...
(3) θy = jan −' (y/L3)” (y/L
x ) - (1/3> (y/L3) 3... (
4) A designation signal for the deflection angle (θX, θy) in the X and Y directions is created using the third-order polynomial expansion approximation formula, and this is transmitted through the drive circuits 11b and 12b to the rotation angle designation signal (θx, ay).
The signal is supplied to the X-axis and Y-axis galvanometers 3a and 9a, respectively.

In addition, in this laser processing optical system where a converging lens is installed before the beam positioner, if the position of the converging lens is fixed, the optical path length between the converging lens and the irradiation position will depend on the beam deflection angle. changes, and the beam diameter changes depending on the irradiation position.

Therefore, in order to maintain the optical path length at a constant value regardless of the deflection angle, the position of the converging lens 3 is changed in the optical axis direction according to the deflection angle.

The rotation angles of the X-axis and Y-axis deflection mirrors 8b and 9b are respectively θ
If x5 θy, the optical path length from the converging lens 3 to the irradiation position is L=L.

+ (Lx /cos θX) +Ls /cos (tan -'tan"llx
+ tan” fly )/Lz)t #L + +Lz (1+(1/2) (x/ CLt +L
3 ) ) ' )+Li (1+(1/2) (
(x/ (L, +L3))”+ (y/Li)”
)”)・・・・(5)

If the position of the converging lens 3 in the optical axis direction is controlled so that this optical path length becomes a constant value that is approximately equal to the focal length of the converging lens 3 regardless of the deflection angle, it will not depend on the irradiation position on the workpiece. The beam diameter is always constant, allowing uniform and highly accurate processing.

The amount of change ΔL (x, y) in the optical path length from the converging lens 3 to the workpiece due to deflection is ΔL (x, y) = (1/2) (Lt (X/ (Lx + l, ,
) ) ' +L 5 ((x/(Lx +L, l))
"+ (y/L!")")... (6)

The calculation circuit 13a in the calculation/drive unit 7 calculates the amount of change ΔL in the optical path length from the specified signal of the irradiation position (x, y) supplied from the control unit 6 according to equation (6), and calculates the amount of change ΔL in the optical path length.
A control signal for the voice coil type linear motor 4 is output from b. Upon receiving this control signal, the voice coil type linear motor 4 moves the converging lens 3 forward by ΔL in the optical axis direction, thereby canceling out the expansion of the optical path length due to the deflection.

The configuration above uses a voice coil type linear motor to move the converging lens in the optical axis direction, but other suitable linear drive mechanisms such as piezoelectric elements or magnetostrictive elements may be used depending on the range of required movement length. You can also do that.

Further, although a configuration using a galvanometer type deflector as the beam positioner has been exemplified, it is also possible to use an appropriate deflector such as a rotating polygon mirror.

Furthermore, the non-linear relationship between the designated irradiation position and the rotation angle is
Although we have exemplified a configuration that approximates using the following expansion formula, depending on the required accuracy, a higher-order expansion formula may be used, or a ROM coefficient unit may be used to correct non-linear relationships and optical path length. You may do so.

Furthermore, although a configuration in which an Nd:YAG laser head is used as a laser light source has been illustrated, the present invention can also be applied to a laser processing apparatus that uses other appropriate laser light sources such as a carbon dioxide laser.

Effects of the Invention As explained in detail above, the laser processing optical device of the present invention includes a converging lens installed in the optical path between the laser light source and the beam positioner, and a converging lens installed in the optical path between the converging lens and the irradiation position. The position of this converging lens is controlled in the optical axis direction so that the length remains constant regardless of the irradiation position, so fluctuations in the beam diameter due to changes in the irradiation position are effectively prevented and high-precision processing is achieved. This makes it possible to eliminate the need for a complicated and expensive f-theta lens, making it possible to reduce the cost of the entire device.

In addition, since the control method of the present invention is entirely performed electrically,
Compared to the fθ lens system, in which a predetermined distortion aberration is achieved by optical techniques such as a combination of special lenses and lens processing, it is possible to achieve higher precision of -i and lower cost.

[Brief explanation of drawings]

FIG. 1 is a block diagram illustrating the configuration of a laser processing optical device according to an embodiment of the present invention, and FIG. 2 is a block diagram illustrating the configuration of the calculation/drive section 7 in FIG. 1. 1. Nd:YAG laser head, 2. Beam expander, 3. Converging lens, 4. Voice coil type linear motor, 5. Galvanometer type beam positioner,
6...Control unit, 7...Calculation/drive unit, 8b...X-axis deflection mirror, 9b...Y-axis deflection mirror, lla...X-axis arithmetic circuit, 12a...Y-axis arithmetic circuit, 13a...light path Long change amount calculation circuit.

Claims (1)

[Claims] A laser processing optical device including a laser light source and a beam positioner that positions a laser beam emitted from the laser light source to a processing position, which is installed in an optical path between the laser light source and the beam positioner. a convergent lens that is irradiated, a drive unit that displaces the convergent lens in the optical axis direction, a beam positioner that controls a beam positioner based on an irradiation position designation signal, and an optical path length between the designated irradiation position and the convergence lens that is a constant value. What is claimed is: 1. A laser processing optical device comprising: a controller for controlling the driving device;