JP3208730B2 - Marking method of light transmissive material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for marking a light transmitting material, and more particularly to a method for marking a light transmitting material using laser light.

[0002]

2. Description of the Related Art A conventional marking method using a laser beam uses the ablation (explosion) phenomenon by a laser beam to process a surface of a material to be marked such as a transparent glass substrate. There is a problem that the surface of the material is minutely cracked and the fragments are mixed in the production process.

For example, FIG. 9 is a cross-sectional side view of a material to be marked by a conventional method for marking a light-transmitting material, and a predetermined portion of a surface 2 of a transparent glass substrate 1 (light-transmitting material) as the material to be marked. The laser beam 3 is focused on the surface 2 and the glass on the surface 2 is blown off by the ablation to form a depression.
I do. In addition to the processing method by the ablation, a depression may be formed by deformation of the surface 2 due to heat generated by absorption of the laser beam 3, and visibility as the marking 4 may be obtained. In the case of processing by this heat, it is considered that the surface once melts and follows the process of re-solidification, and in this case, cracks and the like may occur, and fine fragments and fine pieces may be generated, and these Must be removed.

As a result of the formation of the markings 4, the glass material blown off by ablation becomes powder and adheres to the vicinity of the markings 4 to form an adhering substance called "debris". Surface 2 of 1
There is a problem that cleaning is required.

Further, systems that require a clean environment, such as spraying a gas onto the surface 2 to reduce debris and requiring re-irradiation of a laser beam 3 called a cleaning shot, are not acceptable. There is a problem that it is a desired marking method (processing method).

[0006] In order to solve the above-mentioned problems and to perform marking on the light transmitting material, a method of condensing a laser beam or the like inside the light transmitting material has been proposed. For example, in Japanese Patent Publication No. 7-69524, “a method for manufacturing a spectacle frame part with a pattern and a spectacle frame part”, a scorch is caused by absorbing laser light inside a plastic which is a kind of light transmitting material. This is to make the pattern appear inside. In this method, it is necessary to use a transparent plastic that absorbs laser light as the light-transmitting material.On the other hand, plastic cannot be mixed into the glass substrate, and the glass disclosed in this method cannot be used. It is not possible to cause scorching within the substrate.

Japanese Patent Application Laid-Open No. 3-124486 discloses a laser marking method in which a laser beam is focused inside glass and a mark is formed without damaging the surface. In this method, since the breakdown threshold inside the glass is about 5 to 20 times that of the surface, the laser beam is focused only inside the glass, and the internal breakdown threshold is reduced without damaging the surface. It is intended to exceed this. However, in this embodiment, plastic is used as the material to be marked, and a diameter of 20 to 40 μm and a depth of 100 to
It is said that melting, alteration, and the like occur over a range of about 250 μm.

When the present inventor applied this method to a glass material, cracks were found inside the glass due to the laser light exceeding the breakdown threshold inside the glass. However, it has been found that this method cannot set the internal depth at which the laser light is focused to a desired value. Further, there is a problem that a crack is generated on the surface unless the depth at which the laser light is focused is precisely controlled.

Further, in the "marking method" of Japanese Patent Application Laid-Open No. 4-71792, marking is performed by irradiating the inside of a transparent substrate with a laser beam so that the laser beam is focused and selectively opaque. According to this method, the material is made opaque due to dielectric breakdown.
, The interior of a quartz substrate about 2.3 mm thick becomes opaque and can be identified as a white code when viewed from the surface. Therefore, there is a problem that the method cannot be applied unless the transparent substrate is sufficiently thick as a target material for marking. That is, in the case of a thin transparent substrate, it is difficult to appropriately and precisely control the depth of focusing of the laser beam.

[0010] In Japanese Patent Application Laid-Open No. 6-500275, "hidden surface marking" also targets relatively thick materials, and the possibility of three-dimensional marking is suggested.

None of the above-mentioned marking methods is sufficient to precisely mark a light-transmissive material such as a thin glass material to a predetermined depth or thickness. On the other hand, in order to perform marking on a thin light-transmitting material such as a glass substrate, for example, it is desired to use a mark having little effect on deterioration of the strength of the material.

A detailed observation of the phenomenon in which laser light is focused to cause dielectric breakdown is as follows. FIG.
FIG. 4 is an enlarged cross-sectional side view of a main part of the transparent glass substrate 1, where a crack 5 is formed inside the glass in the vicinity where the laser beam 3 is most focused, and a crack 6 is propagated in the laser incident direction following the crack 5. Hole-shaped mark pattern 7
Is observed. Beam diameter of laser light 3 3mm
φ, energy about 400μJ, focal length f = 100m
When a lens having a size of m is used, the size of the crack 5 is about 100 μm,
Has a length of about 500 μm.

Even when the mark pattern 7 having such a size and shape is generated, for example, the thickness is 1 to 2 m.
It is expected that when marking a thin transparent glass substrate 1 having a thickness of about m, the mark pattern 7 can be applied only inside the glass if the lens position from the surface 2 is accurately controlled. However, since the breaking threshold of the glass surface 2 was lower than that of the inside, it was found that cracks 5 or cracks 6 were actually formed on the front surface 2 or the back surface 2A of the transparent glass substrate 1. Surface 2
In addition, when the crack 5 or the crack 6 is formed on the back surface 2A, there is a problem that not only the material strength sharply deteriorates but also particles that jump out of the material are generated.

As a general method for preventing cracks on the surface of a light transmitting material such as a glass material, the intensity of the laser beam is reduced to a certain value or less, the mark size is reduced, and the aperture ratio of the condensing optical system is reduced. Increasing (diameter of lens / focal length), in particular, suppressing the growth of marks on the surface can be considered. However, even if the size and shape of the mark pattern 7 are properly controlled by controlling the irradiation energy of the laser beam 3 and adjusting the lens position and selecting the aperture ratio, cracks 5 or cracks 6 on the surface 2 are generated. The cause is that cracks 5 and cracks 6 are generated mainly due to the uneven surface or minute scratches originally present on the surface 2 and that dust is attached to the surface 2. The dust becomes the center of absorption of the laser beam 3 and the laser beam 3
The environment is likely to absorb more energy than expected.

In any case, it is understood that the focusing of the laser beam 3 only on the inside of the transparent glass substrate 1 needs to be performed more precisely than expected. In particular, marking is performed on a thin glass material or the like. In such a case, it can be seen that it is difficult to realize the conventional marking methods. Also,
In the case where the cracks 5 are used as the markings, since the operation of condensing the laser beam 3 and the control of the condensing portion need to be performed precisely, the marking on the thin transparent glass substrate 1 (light transmitting material) is particularly required. The method seems to have its limitations.

[0016]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a method of marking a light-transmitting material suitable for a clean system.

Another object of the present invention is to provide a method of marking a light-transmitting material so that fragments of the material to be marked are not generated by the marking.

Another object of the present invention is to provide a method for marking a light transmitting material which does not require a post-treatment for cleaning the surface of the light transmitting material after marking.

The present invention is also directed to a marking of a light-transmitting material which is capable of precisely adjusting the marking position to a predetermined depth and particularly to a thin glass material so as not to cause cracks or the like on its surface. It is an object to provide a method.

[0020]

That is, according to the present invention, in marking a transparent material such as a transparent glass substrate with a laser beam, the laser beam is focused not on the surface of the transparent material but on the inside thereof. Focusing not only on marking by the generation of cracks but also by using laser light with a lower irradiation energy to change the optical properties of the light-transmissive material and use it for marking. In the method of marking a light-transmitting material for marking a light-transmitting material with a laser beam, the light-transmitting material is a glass material, and the laser beam is used as the laser light. While selecting a transmissive one, and condensing this laser light at a predetermined depth inside the light transmissive material, A marking method of a light transmissive material, characterized in that the intensity of the laser beam was set to allow the marking as the degree of intensity to cause a change in the optical properties of the light transmissive material. The change in the optical properties refers to, for example, a change in the refractive index or any other optical property, which can be recognized from outside by a predetermined measuring means.

[0021] A portion where the optical property of the light transmitting material changes due to the laser light can be long in the depth direction of the light transmitting material.

A plurality of portions where the optical properties of the light transmitting material are changed by the laser beam can be combined into one marking unit. At this time, even if cracks occur, it is necessary to provide an interval between them so that they are not connected.

A femtosecond laser can be used as a laser light source of the laser light.

In the method for marking a light-transmitting material according to the present invention, when the laser light is focused on a predetermined portion inside the light-transmitting material, the light density increases, and when the light exceeds a predetermined breaking threshold. It is thought that absorption is caused by optical non-linear phenomena. Based on this absorption, marking is made inside the light-transmitting material using the phenomenon that the optical properties of light-transmitting materials such as transparent glass substrates change. It is.

By using, for example, an fθ lens for condensing the laser light, the light transmitting material is moved with respect to the laser light, the condensing portion of the laser light is moved, and a predetermined spread area is obtained. Even when marking characters or figures are drawn, the laser light can be focused on the same level (depth position). Therefore, even in the case of a thin glass material having a thickness of about 1 to 2 mm or less, the portion where the optical property changes within this thickness is limited, and the surface is not damaged by cracks and damage is caused. It is possible to make no marking.

It is to be noted that any laser light may be used in combination with a light transmitting material. For example, for quartz glass, the infrared region,
Laser light having a wavelength in the visible light region or ultraviolet region can be used, and for general sheet glass,
Laser light having a wavelength in the infrared region or the visible light region can be used.

As a laser light source, YA which is easy to operate
An LD-pumped solid-state laser such as a G laser or a YLF laser is convenient. For example, when a YAG laser that oscillates a laser beam having a wavelength in the infrared region is used, if this is converted into a second harmonic by using a wavelength converter, it can be used in the visible light region, and can be used in the third or fourth harmonic. If it is a harmonic wave, it can be used in the ultraviolet region. The higher the frequency of the laser beam used, that is, the shorter the wavelength, the better the resolution as marking. Furthermore, as a laser light source,
A pulse laser can perform marking with good controllability, and a pulse having a short pulse width is advantageous because the marking can be uniformly aligned in the depth direction. This is because the thermal effect is proportional to the square root of the pulse width (time). For this reason, it is useful to use a laser light source of sub-nanosecond or less (for example, a femtosecond laser having a pulse width on the order of 10 ⁻¹⁵ seconds).

The present invention is based on the fact that it is difficult for the conventional various marking methods to make a mark inside a thin light-transmitting material, particularly, because the generation of cracks due to the condensing of laser light is caused by the surface of the light-transmitting material. To reduce its mechanical strength, and it is actually very difficult to prevent cracks from reaching the surface if all marks are caused by crack generation. Focusing attention, laser light having an intensity within a range that does not cause cracks is irradiated. Furthermore, it is more preferable to focus on the point where the light condensing position shifts to the front side with the marking in the normal lens, and by using the fθ lens, the light is condensed at a certain depth position inside the glass. Further, it is presumed that the conventional method does not take into account the refractive index of the light-transmitting material, so that the positions of the front and back surfaces of the glass are accurately measured, and the glass is taken into account taking into account the refractive index of the glass. By illuminating, etc., it is possible to more accurately perform internal marking of a thin glass substrate.

In the present invention, marking is performed not on the surface of the light-transmitting material but on the inside of the light-transmitting material by the laser beam. Marking can be performed, and there is no problem that fragments are mixed in the production process. Moreover, since the marking is formed not only by the generation of cracks but also by the change of the optical properties of the light-transmitting material due to the condensing of the laser beam, the destruction of the light-transmitting material is avoided, and Marking can be performed without generating fine fragments and fragments. further,
If the marking is performed while controlling the light-condensing depth according to the refractive index by adopting the fθ lens and focusing on the refractive index of the glass material, the light-condensing position or the depth can be specified precisely.

By forming a portion where the optical property of the light transmitting material changes due to the laser beam in the depth direction of the light transmitting material, the portion where the optical property changes overlaps in the depth direction. The marking can be visually recognized in the depth direction (thickness direction) of the light transmissive material, and the marking cannot be visually recognized from the side surface direction.

Further, a plurality of portions (for example, 4
By using one marking unit as a whole, reading by the optical reading means can be performed together with visual recognition by the naked eye.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a method for marking a light-transmitting material according to an embodiment of the present invention will be described with reference to FIGS. However, the same parts as those in FIGS. 9 and 10 are denoted by the same reference numerals, and detailed description thereof will be omitted. FIG.
Is a marking device 10 that performs the marking method.
3 is a perspective view of the marking device 10, a laser light source 11, a beam shaper 12, a galvanomirror 13
And an fθ lens 14. The fθ lens 14 allows the laser beam 3 to be focused on the inside 15 (FIG. 2) of the transparent glass substrate 1. As the laser light source 11, for example, a fourth harmonic (a pulse width of about 10 ns) of a YLF laser is used. lens having a focal length of 50 mm, for example. As the transparent glass substrate 1, for example, a synthetic quartz substrate (10 mm in thickness) is used.

FIG. 2 is a cross-sectional side view of the transparent glass substrate 1. The laser beam 3 can be focused on the inside 15 of the transparent glass substrate 1 instead of the surface 2 of the transparent glass substrate 1.

Assuming that the refractive index of the transparent glass substrate 1 (the material to be marked) is n and the depth of the focal point P without the transparent glass substrate 1 is H1, the effect of the refraction of the laser beam 3 in the interior 15 As a result, the actual depth H2 of the focal point Q
Moves from the surface 2 side to H1 × n. In particular, when marking is performed on the thin transparent glass substrate 1, the actual depth H2 of the focal point Q is an important factor. In other words, precise marking can be performed by precisely controlling the position (depth H2) of the actual converging point Q according to the value of the refractive index n.

In the conventional marking method, as shown in FIG. 9, by irradiating the laser beam 3 on the surface 2 of the transparent glass substrate 1 multiple times, the hole as the marking 4 is made longer and longer in the depth direction. I was trying to do it. Alternatively, a crack 5 composed of a crack 6 and a mark pattern 7 is formed as shown in FIG.

In the method for marking a light transmissive material according to the present invention, as shown in FIG.
Is focused (condensing point Q) on the inside 15 and a laser beam 3 having lower energy than before is irradiated. At this condensing point Q, phenomena such as optical damage or optical insulation breakdown are minimized and transparent. The linear mark pattern 1 is generated by causing a change in the optical properties of the glass substrate 1.
Draw 6. That is, when the laser beam 3 is condensed on the converging point Q, nonlinear absorption of the laser beam 3 occurs, and the optical properties (for example, refractive index) of this portion change, and the tip portion 17 (condensing portion) of the laser beam 3 changes. Laser light 3 from point Q)
It has been observed that a depth portion 18 of the mark pattern 16 extends in the direction of the incident side surface 2.

FIG. 3 is an enlarged side view of the mark pattern 16. The mark pattern 16 can be visually recognized in a substantially circular shape when viewed in the depth direction of the transparent glass substrate 1. Can be virtually invisible (virtual line in the figure). That is, according to the present invention, since the change in the optical property is very small, it is possible to detect the change only by illuminating the mark pattern 16 from the length direction (mark pattern 1).
6 cannot be detected by irradiation from the lateral direction), so that marking as a so-called hidden mark becomes possible.

Conventionally, when the mark pattern 16 (mark pattern 7) reaches the surface 2, the transparent glass substrate 1 may be broken.
Is irradiated with the incident energy of the laser beam 3 in a range where the laser beam 3 remains within the inside 15 of the transparent glass substrate 1. Conventionally, for example, a transparent glass substrate 1 having a thickness of 1.1 mm or more
Was irradiated with the laser beam 3 having an irradiation energy of 400 μJ. However, for the transparent glass substrate 1 having a thickness of 1.1 mm or less, the crack 5 may reach the surface 2 due to the fluctuation of the laser energy. It is estimated that this can happen stochastically. The present inventor has proposed a transparent glass substrate 1
Specifically, a beam diameter of the laser beam 3 of about 10 mm is applied to a soda-lime glass material and a non-alkali glass material.
It has been experimentally confirmed that when a lens having a diameter of 28 mm and a focal length of 28 mm is irradiated with an energy of about 100 μJ, cracks 5 or cracks 6 do not occur and optical properties (refractive index) change. . That is, it has been confirmed that the soda-lime glass material has no crack on the surface of the material having a thickness of 1.1 mm and 0.7 mm. In addition, it has been confirmed that cracks do not occur on the material surfaces of the non-alkali glass materials having a thickness of 1.1 mm, 0.7 mm and 0.4 mm. 1.1m
It can be seen that the present invention can be applied to glass materials of m or less.

Further, in the embodiment using a femtosecond laser having a pulse width on the order of 10 ^-15 seconds as a laser light source, the energy range in which the refractive index of the transparent glass substrate 1 can be changed is wide. found.
That is, a sapphire laser with a pulse width of about 100 femtoseconds was used as the light source, the center wavelength was 800 nm (infrared ray region), the aperture ratio of the lens used was 0.28, and soda lime glass was used as a sample of the transparent glass substrate 1. Marking was performed by changing the energy and the energy.

FIG. 4 is a view showing the inside of the transparent glass substrate 1 according to the combination of the number of shots (number of pulses) and energy.
FIG. 11 is an explanatory plan view showing a state where cracks 5 to cracks 6 (FIG. 10) and mark patterns 16 (FIG. 3) have occurred in FIG. Specifically, the number of pulses is 1000, 1
The test was performed under three conditions of 25 and 8 pulses and three conditions of 70, 7, and 0.7 μJ as energy per unit pulse. As shown in the figure, when the energy is at a level of 70 μJ / pulse, a crack 5 occurs regardless of the number of pulses,
At the level of 7 μJ / pulse, even if multiple radiations such as 1000 pulses are performed, the cracks 5 do not propagate, and the mark pattern 16 described with reference to FIG. 3 can be formed. In addition, when the energy was the same, it was found that the smaller the number of pulses, the smaller the degree of change.

FIG. 5 shows a portion V (energy 70 μm) in FIG.
J, 8 pulses) in an enlarged sectional view in the thickness direction, FIG.
FIG. 5 is an enlarged cross-sectional view in a thickness direction of a VI portion (energy: 7 μJ, 1000 pulses) in FIG. 4. As shown in FIG. 5, cracks 5 caused by the femtosecond laser
The crack 6 has a width of several μm or less. FIG.
As shown in FIG. 3, in the processing of 1,000 pulses at an energy of 7 μJ, no crack 5 or crack 6 is generated, the energy is dispersed in the vertical direction (thickness direction), and the mark pattern 16 (FIG. ), The length is also about 40 μm, and it was found that good results were obtained.

When a nanosecond laser is used as compared with the above-described femtosecond laser, the range of energy that causes a change in the refractive index of the transparent glass substrate 1 is extremely narrow,
If the energy is large, the crack 5 develops, while if the energy is small, the refractive index does not change. That is, a femtosecond laser has a wide energy range that causes a change in the refractive index, and this controllability is a desirable characteristic from the viewpoint of industrially using laser marking.

Generally, the fluctuation range of the laser energy is estimated to be about ± 5%.
, And a threshold value T2 for causing optical damage corresponding to the mark pattern 7.
Even if the relationship of T1 <T2 is established between the threshold values T1 and T2, if the threshold values T1 and T2 have close values,
It is difficult to keep the laser energy below T1, and practically, marking is performed near T1. In this case, a so-called crack 5 or a crack 6 is generated in a part of the mark pattern. However, all of the marks are individually marked with the mark pattern 7 formed by the crack 5 or the crack 6 (that is, processing in T2). The size of the crack 5 or the crack 6 can be reduced. Therefore, even if cracks 5 or cracks 6 are generated to some extent, they are small, and it is possible to prevent the cracks 6 from reaching the surface 2 of the transparent glass substrate 1 at a probability close to zero, and to prevent them. In other words, in practice,
Marking without scratches on the surface 2 can be realized.

Therefore, in general, the visibility is much improved by enlarging the range of the mark pattern 7 due to optical damage. However, when the mark pattern 7 is enlarged, the crack 6 or the crack 5 (FIG. 10) In the present invention, the irradiation energy of the laser beam 3 is reduced to eliminate optical damage, or to reduce the diameter of the laser light 3 as much as possible, or to reduce the diameter of the transparent glass substrate 1 as much as possible, or to prevent optical damage. Instead, the irradiation energy is kept at a level that causes a change in the optical properties of the transparent glass substrate 1.

FIG. 7 is an enlarged plan view of a portion of the mark pattern 16 on the transparent glass substrate 1 and shows cracks 5.
Mark pattern 16 with poor visibility compared to (FIG. 10)
Can be dealt with by increasing the number of dots (the number of dots). That is, for example, four mark patterns 1
6, and by adjusting the interval between them (for example, the interval between the mark patterns 16 is set to 40 μm as shown in the figure), even if a crack occurs, the cracks can communicate with each other. One marking unit 19 can be formed without performing.

Next, a streaky mark pattern 1 caused by a change in optical properties due to the actual irradiation of the laser beam 3
6, the transparent glass substrate 1 is moved in the length direction (in the example shown in FIG. 2, the transparent glass substrate 1 is moved downward in the figure).
5 so that the mark pattern 16 is located at the center.
Of course, predetermined characters or figures are drawn by moving the transparent glass substrate 1 in the horizontal and oblique directions in the figure.
The length and thickness of the mark pattern 16 are
This can be adjusted by the degree of the stop, the degree of increase or decrease of the light amount of the laser beam 3, or by changing the focal length of the fθ lens 14.

The light transmissive material is moved with respect to the laser beam 3, and the converging portion (condensing point Q) of the laser beam 3 is moved.
Even if a marking character or figure having a predetermined spread area is drawn, the use of the fθ lens 14 allows the laser beam to be focused on the same level (depth position). That is, FIG.
FIG. 7 is a cross-sectional view of a main part comparing a case of focusing with 0 (left side in the figure) and a case of focusing with the fθ lens 14 (right side in the figure).
Is used, since the operation of the transparent glass substrate 1 is generally a parallel movement from the initial position with respect to the optical system,
The converging point 21 moves toward the front surface 2 of the transparent glass substrate 1 under the influence of the aberration of the lens 20 as it deviates from its optical axis as a marking character or figure is drawn. In other words, D2 is smaller (shallower) between the depth D1 of the focal point 21 at the optical axis portion and the depth D2 at a position shifted from the optical axis portion. For this reason, in processing using a normal lens 20, it is necessary to move the transparent glass substrate 1 with the optical system fixed. As the moving device, for example, an XY stage (not shown)
A transparent glass substrate 1 is placed on the top, and marking characters or figures are drawn by moving this stage. In this processing method, the processing speed is limited by the moving speed of the stage,
Marking unit 19 having a plurality of mark patterns 16
It is difficult to process at high speed. On the other hand, when the fθ lens 14 is used, the fθ lens 14 is designed in consideration of the thickness and the refractive index n of the transparent glass substrate 1 of the workpiece to draw marking characters or figures. Also, it is possible to maintain the state in which the light converging point Q is horizontal or equidistant with respect to the surface 2, and the depth of the light converging point Q can be kept constant at H2 (FIG. 2). That is, to focus the laser beam 3, f
If the θ lens 14 is used, the focusing point Q can be precisely adjusted at a constant depth in the thickness direction even if the transparent glass substrate 1 is particularly thin, and marking can be performed effectively. It is possible to scan light with extremely high speed by the galvanometer mirror 13.

It is to be noted that, if the thickness of the transparent glass substrate 1 is increased or the length of the mark pattern 16 is further shortened to change the depth of the inside 15, the three-dimensional marking is performed. Is also possible.

[0049]

As described above, according to the present invention, laser light is condensed inside a light-transmitting material such as a transparent glass substrate to absorb the laser light inside, and to generate cracks or cracks as much as possible. Instead, we changed the optical properties to make markings,
Since the light-transmitting material is prevented from being damaged due to the marking, and no debris is generated due to the marking, the method is suitable as a method for marking a light-transmitting material used in a clean system.

[Brief description of the drawings]

FIG. 1 is a perspective view of a marking device 10 for performing a method for marking a light-transmitting material according to the present invention.

FIG. 2 is a side sectional view of the transparent glass substrate 1. FIG.

FIG. 3 is an enlarged side view of a mark pattern 16 of the same.

FIG. 4 is a plan view showing a state of occurrence of a crack 5 or a crack 6 (FIG. 10) and a mark pattern 16 (FIG. 3) in the inside 15 of the transparent glass substrate 1 by a combination of the number of shots (number of pulses) and energy. FIG.

FIG. 5 is an enlarged cross-sectional view in a thickness direction of a V portion (energy: 70 μJ, 8 pulses) in FIG. 4;

FIG. 6 shows a VI portion (energy 7 μJ, 1000
FIG. 4 is an enlarged cross-sectional view of a (pulse) in a thickness direction.

FIG. 7 is an enlarged plan view of a mark pattern 16 (marking unit 19) on the transparent glass substrate 1;

FIG. 8 is a cross-sectional view of a main part comparing the case of condensing with a normal lens 20 (left side in the figure) and the case of condensing with an fθ lens 14 (right side in the figure).

FIG. 9 is a cross-sectional side view of a material to be marked (transparent glass substrate 1) by a conventional method of marking a light transmitting material.

FIG. 10 is an enlarged sectional side view of a main part of the transparent glass substrate 1;

[Explanation of symbols]

Reference Signs List 1 transparent glass substrate (material to be marked, light transmissive material) 2 surface of transparent glass substrate 1 3 laser beam 4 marking on surface 2 (FIG. 9) 5 crack (FIG. 10) 6 crack continuous to crack 5 in laser incident direction 7 Hole-shaped mark pattern 10 Marking device (FIG. 1) 11 Laser light source 12 Beam shaper 13 Galvano mirror 14 fθ lens 15 Inside transparent glass substrate 1 16 Linear mark pattern 17 Tip part of mark pattern 16 18 Mark pattern 16 19 One marking unit with four mark patterns 16 20 Normal lens 21 Focus point when using normal lens 20 n Refractive index of transparent glass substrate 1 (material to be marked) H1 Transparent glass Depth H2 of converging point P without substrate 1 of actual converging point Q H2 (= H1 × n) P Focus point when there is no transparent glass substrate 1 Q Actual focus point due to the effect of refraction of laser beam 3 inside 15 D1 Focus point when ordinary lens 20 is used Depth at the optical axis portion of the light spot 21 D2 Depth of a position shifted from the optical axis portion of the light converging point 21 when the ordinary lens 20 is used (D2 <D1)

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ identification code FI H01S 3/16 B41M 5/26 S (58) Field surveyed (Int.Cl. ⁷ , DB name) B23K 26/00 B23K 26 / 04 B41M 5/26 C03C 23/00 H01S 3/00 H01S 3/16

Claims (5)

(57) [Claims] 1. A method of marking a light-transmitting material using a laser beam to mark the light-transmitting material, wherein the light-transmitting material is a glass material, and the light-transmitting material is a laser beam. The laser beam is selected to be transparent to the transparent material, and the laser beam is focused at a predetermined depth inside the light-transmissive material, and the intensity of the laser beam is set to 7 μJ / pulse or less.
A method for marking a light transmitting material , wherein the marking is made possible by causing a change in the refractive index of the light transmitting material. 2. A laser transmitting light to a light transmitting material.
A method for marking a light-transmitting material to be subjected to king, wherein the laser light is transmitted to the light-transmitting material.
Select a material having a property that is suitable for the refractive index of the light-transmitting material.
Controlling the focusing depth of the laser light,
Focuses the laser light at a predetermined depth inside the conductive material
At the same time, the intensity of the laser light is changed by the change in the refractive index of the light transmitting material.
The marking is possible as strong as
A marking method for a light-transmitting material, characterized in that: There claim 1 wherein causing long portion where the refractive index changes in the light transmitting material according to the laser beam in the depth direction of the light transmissive material
3. The method for marking a light-transmitting material according to claim 2 . 4. A Ah claim 1, characterized in that a plurality collectively one marking unit sites whose refractive index changes in the light transmitting material according to the laser beam
Or the method for marking a light-transmitting material according to 2 . As the laser light source according to claim 5, wherein said laser beam, according to claim 1 or 2 marking method of a light transmissive material, wherein employing a femtosecond laser.