JPH01313195A - Laser beam marking device - Google Patents

Abstract

PURPOSE:To obtain fine marking with constant quality by providing a collimator which converges once at least a laser beam after passing through a mask and again spreads the beam to return it to parallel luminous fluxes and incorporating a diaphragm to intercept an axial outer beam into the collimator. CONSTITUTION:A laser luminous flux emitted from a laser beam oscillator 1 is shaped in a proper cross-sectional shape by a beam shaping optical system 2 and then, projected on the mask 3. The laser luminous flux after passing through the mask 3 is converged by a collimator first lens 7 and passes a focus 10 but the axial outer beam due to the spread of the laser beam and the beam other than parallel components by the diffraction and diffusion on the mask 3 cannot passes the focus 10. The laser beam emitted from a collimator second lens 8 is made to only the parallel components by the diaphragm 9 and even if a work 5 to be machined is placed on any place on an optical axis behind the collimator second lens 8, the clear marking with the same size can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a laser marking device, and particularly to an improvement in its marking optical system.

(Prior Art) Conventionally, a laser marking device is configured as shown in FIG. Shaped to have a cross-sectional shape. The mask 3 is irradiated with this shaped laser light. This mask 3 has a pattern to be marked, for example, in a part that transmits laser light and a part that blocks laser light. The laser light that has passed through the mask 3 is irradiated onto the workpiece 5 through an imaging lens 4 made up of one or more assembled lenses.

At this time, since the pattern formed on the mask 3 is imaged onto the workpiece 5 by the imaging lens 4, the pattern of the mask 3 is marked on the workpiece 5.

The mask 3 may be made of various types, such as one made by punching out a metal plate, one made of frosted glass, or one made of an inorganic material baked on the glass surface.

(Problem to be Solved by the Invention) In the conventional laser marking device described above, in order to image the pattern of the mask 3 using the imaging lens 4,
needs to be installed at an imaging position determined by the distance between the mask 3 and the imaging lens 4 and the focal length of the imaging lens 4.

When a parallel light beam such as a laser is used as a light source, there is basically no blurring of the image even at positions other than the imaging point. However, in reality, if the workpiece 5 moves from the imaging position due to the spread angle of the laser beam or the diffracted light or scattered light when passing through the mask 3, the image will become blurred and clear marking with good contrast will not be possible. I can't get it. Furthermore, since the laser beam converges and diverges by passing through the imaging lens 4,
The size of the image changes depending on the position of the workpiece 5.

Therefore, if the surface of the workpiece 5 has irregularities or is not flat, a proper image will not be formed and good marking will not be possible. In addition, such a laser marking device requires a manual or automatic adjustment mechanism to maintain the surface of the workpiece 5 at the imaging point, which has the disadvantage of being expensive.

The present invention was made in view of the above circumstances, and an object of the present invention is to provide a laser marking device that can perform good marking even when the surface of a workpiece is uneven.

[Structure of the Invention] (Means for Solving the Problems) This invention provides a method for converting laser light emitted from a laser oscillator into
In a laser marking device that marks a pattern of the mask on the workpiece by irradiating the workpiece through at least a lens and a mask, the laser beam is converged at least once after passing through the mask; A collimator is installed to expand the beam again and return it to a parallel beam.
This is a laser marking device with a diaphragm built into the collimator.

(Operation) According to this invention, when the surface of the workpiece is not flat,
Even when there are unevenness, good marking is achieved. Further, even if the workpieces have different sizes and it is difficult to keep the marking surface position constant, marking can be performed without problems.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

The laser marking device according to the present invention is constructed as shown in FIG. 1, and the same parts as in the conventional example (FIG. 2) are given the same reference numerals.

That is, on the optical axis of the laser beam emitted from the laser oscillator 1, a beam shaping optical system 2 consisting of two convex lenses, a mask 3, and a collimator 6 are sequentially arranged at a predetermined interval.

In this case, the collimator 6 includes a collimator lens 7 that converges the laser beam and a collimator second lens 8 that returns the laser beam to a parallel beam.

Further, at a position where the laser beam is converged by the collimator lens 7 (hereinafter referred to as a focal point 10), an aperture 9 is provided to block rays other than the chief ray passing through the focal point 10. The workpiece 5 can be placed anywhere as long as it is on the laser optical axis of the collimator 6, and is usually placed in a place where it will not be affected by a holding jig for the workpiece 5 or smoke generated during marking. Place it in an appropriate position.

During operation, the laser beam emitted from the laser oscillator 1 is shaped into an appropriate cross-sectional shape by the beam shaping optical system 2, and then irradiated onto the mask 3, as in the prior art. The laser beam passing through the mask 3 is converged by the collimator lens 7 and passes through the focal point 10, but off-axis light due to the spread of the laser beam and light other than parallel components due to diffraction and scattering at the mask 3 are , the laser beam cannot pass through the focal point 10, and the laser beam emitted from the collimator second lens 8 becomes only parallel components due to the aperture 9 provided here.
No matter where the workpiece 5 is placed on the optical axis after the mark, clear markings of the same size can be made.

In this way, according to the present invention, good marking can be achieved even when the surface of the workpiece 5 is not flat or uneven. Furthermore, even if the workpieces 5 have different sizes and it is difficult to keep the position of the marking surface constant, marking can be performed without problems.

(Other Examples) In the above example, the focal position of the collimator lens 7 and the focal position of the collimator second lens 8 are both arranged to be at the focal point 10, so that the laser beam emitted from the collimator 6 is made into a parallel beam. However, by moving the position of the collimator second lens 8 in the optical axis direction, the light beam can be expanded or converged. Utilizing this, when the position of the workpiece 5 is fixed, the size of the marking can be adjusted by moving the position of the collimator second lens 8.

Furthermore, by changing the magnification of the collimator 6 composed of the collimator lens 7 and the collimator second lens 8, the mask pattern can be marked at any ratio of reduction, same magnification, or enlargement.

Furthermore, if the mask 3 is a transmission type, it is conceivable to place multiple masks one on top of the other on the optical axis to form a combination pattern, but even in this case, the size of the marking image may vary due to the difference in the position of each mask. Good markings can be obtained without any change or blurring.

[Effects of the Invention] According to the present invention, good marking with constant quality can be obtained regardless of the position of the mask or the position of the workpiece.
It is possible to realize a marking system with a large degree of freedom.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a laser marking device according to an embodiment of the present invention, and FIG. 2 is a schematic diagram showing a conventional laser marking device. 1... Laser oscillator, 2... Beam shaping optical system, 3
...Mask, 5. Workpiece, 6. Collimator, 7. Collimator first lens, 8. Collimator second lens, 9. Aperture, 10. Focus. Applicant's agent Patent attorney Takehiko Suzue

Claims (1)

[Scope of Claims] A laser marking device that marks a pattern of the mask on a workpiece by irradiating the workpiece with a laser beam emitted from a laser oscillator through at least a lens and a mask, comprising: A laser marking device characterized by having a collimator that converges the light at least once after passing through the mask and then expanding it again to return it to a parallel beam, and further comprising a diaphragm within the collimator that blocks off-axis light.