JP7281392B2 - LASER PROCESSING APPARATUS AND LASER PROCESSING METHOD - Google Patents

Description

The present disclosure relates to a laser processing apparatus and a laser processing method.

As a technique in this type of field, there is a laser processing method described in Patent Document 1, for example. This laser processing method is a method of joining a first light-transmitting member and a second light-transmitting member having light-transmitting properties. In this method, in the vicinity of the contact surface between the first light-transmissive member and the second light-transmissive member, a laser beam is irradiated with the focal point aligned with the interior of one of these members. to generate multiphoton absorption. This multiphoton absorption forms a modified region extending over the first light-transmitting member and the second light-transmitting member, and joins the first light-transmitting member and the second light-transmitting member.

JP-A-2005-001172

In the laser processing method as described above, it is conceivable that the processing quality may vary depending on the state of the object to be processed and the state of the laser beam. An example of deterioration in processing quality is the generation of cracks, which are difficult to visually evaluate. Therefore, from the viewpoint of improving the reliability of processing quality, a technology capable of objectively evaluating processing quality is desired.

An object of the present disclosure is to provide a laser processing apparatus and a laser processing method that can objectively evaluate processing quality.

In order to solve the above problems, the inventors of the present application have made intensive research on the type of light-transmitting member that is the object to be processed, the irradiation conditions of the laser beam, and the observation of the end surface of the modified region after processing. It was found that there is a certain correlation between the intensity of light generated by the light-transmitting member during the irradiation period and the state of formation of the modified region. Therefore, by using this correlation, it is possible to objectively evaluate the processing quality without relying on visual observation, and the knowledge that the reliability of the processing quality can be improved has been obtained, leading to the completion of the present disclosure.

A laser processing apparatus according to one aspect of the present disclosure is a laser processing apparatus that joins a first light-transmitting member and a second light-transmitting member by irradiating a laser beam, wherein the first light-transmitting member and near the contact surface of the second light-transmitting member, a laser beam is irradiated with the focal point aligned with the inside of one of these members, and the first light-transmitting member and the second light-transmitting member are irradiated with laser light. a light irradiating part forming a crossing modified region; and light for detecting the intensity of the light to be detected generated by the first light transmissive member and the second light transmissive member in response to the irradiation of the laser light by the light irradiating part. and a detector.

In this laser processing apparatus, the light detecting section detects the intensity of the light to be detected generated by the first light transmitting member and the second light transmitting member in response to the irradiation of the laser light by the light irradiating section. In this laser processing apparatus, the intensity of the light to be detected is determined based on a certain correlation existing between the intensity of the light to be detected generated in the light transmitting member during the irradiation period of the laser light and the state of formation of the modified region. can be used as an index of processing quality. Therefore, the machining quality can be objectively evaluated without relying on visual observation, and the reliability of the machining quality can be improved.

A threshold for the intensity of the light to be detected is stored, and the first light-transmitting member and the second light-transmitting member are selected based on whether the intensity of the light to be detected during the irradiation period of the laser beam is equal to or greater than the threshold. A judging section for judging whether the processing quality is good or bad may be further provided. In this case, based on the intensity of the light to be detected, it is possible to more objectively judge whether the processing quality of the first light-transmissive member and the second light-transmissive member is good or bad.

A permissible range for the intensity of the light to be detected is maintained, and if the intensity of the light to be detected during the irradiation period of the laser light falls outside the permissible range, the laser beam is irradiated so that the intensity of the light to be detected falls within the permissible range. A control section for controlling conditions may be further provided. In this case, since the laser beam is irradiated under the condition that the intensity of the light to be detected is within the allowable range, the processing yield of the first light-transmitting member and the second light-transmitting member can be improved.

The light irradiation section has a condensing lens for condensing the laser light, the light detecting section has a light receiving lens for receiving the light to be detected, and the focal point of the condensing lens and the focal point of the light receiving lens are the condensing points. may match. Thereby, the light to be detected generated near the condensing point can be efficiently detected.

The condenser lens and the light receiving lens may be shared by one objective lens. This simplifies the configuration.

A laser processing method according to one aspect of the present disclosure is a laser processing method for joining a first light-transmitting member and a second light-transmitting member by irradiating a laser beam, wherein the first light-transmitting member and near the contact surface of the second light-transmitting member, a laser beam is irradiated with the focal point aligned with the inside of one of these members, and the first light-transmitting member and the second light-transmitting member are irradiated with laser light. a light irradiation step for forming a modified region across a crossing; and light for detecting the intensity of the light to be detected generated in the first light-transmitting member and the second light-transmitting member in response to the irradiation of the laser light by the light irradiation unit. and a detection step.

In this laser processing method, the intensity of the light to be detected generated by the first light-transmitting member and the second light-transmitting member in response to the irradiation of the laser light is detected. In this laser processing method, the intensity of the light to be detected is determined based on a certain correlation between the intensity of the light to be detected generated in the light transmitting member during the irradiation period of the laser light and the state of formation of the modified region. is used as an index of processing quality. Therefore, the machining quality can be objectively evaluated without relying on visual observation, and the reliability of the machining quality can be improved.

A threshold for the intensity of the light to be detected is stored, and the first light-transmitting member and the second light-transmitting member are selected based on whether the intensity of the light to be detected during the irradiation period of the laser beam is equal to or greater than the threshold. A judgment step for judging whether the processing quality is good or bad may be further provided. In this case, based on the intensity of the light to be detected, it is possible to more objectively judge whether the processing quality of the first light-transmissive member and the second light-transmissive member is good or bad.

A permissible range for the intensity of the light to be detected is maintained, and if the intensity of the light to be detected during the irradiation period of the laser light falls outside the permissible range, the laser beam is irradiated so that the intensity of the light to be detected falls within the permissible range. It may further comprise a control step for controlling conditions. In this case, since the laser beam is irradiated under the condition that the intensity of the light to be detected is within the allowable range, the processing yield of the first light-transmitting member and the second light-transmitting member can be improved.

In the light irradiation step, the laser beam is condensed by the condensing lens, and in the light detection step, the light to be detected is received by the light receiving lens, and the focus of the condensing lens and the focus of the light receiving lens are aligned at the condensing point. good too. Thereby, the light to be detected generated near the condensing point can be efficiently detected.

The condenser lens and the light receiving lens may be shared by one objective lens. This simplifies the configuration.

According to the present disclosure, processing quality can be objectively evaluated.

It is a schematic diagram showing one embodiment of a laser processing device. FIG. 4 is a schematic cross-sectional view showing states of the first light-transmitting member and the second light-transmitting member during laser light irradiation; FIG. 4 is a schematic cross-sectional view showing modified regions formed in a first light-transmitting member and a second light-transmitting member by laser beam scanning; 2 is a flow chart showing the operation of the laser processing apparatus shown in FIG. 1; It is a figure which shows an example of the observation result of the cross section of a modified region. It is a figure which shows the irradiation conditions of the laser beam in a verification test. FIG. 10 is a diagram showing the result of measuring the spectral intensity of light to be detected when a slide glass is processed using an ultraviolet region measurement system; FIG. 10 is a diagram showing the result of measuring the spectral intensity of light to be detected with a visible range measurement system when a slide glass is processed; FIG. 5 is a diagram showing the correlation between the spectral intensity of the light to be detected in the ultraviolet region and the presence or absence of cracks in the case of a slide glass. FIG. 4 is a diagram showing the correlation between the spectral intensity in the visible region of the light to be detected and the presence or absence of cracks in the case of a slide glass. FIG. 5 is a diagram showing the correlation between the spectral intensity of light to be detected and the presence or absence of cracks in the case of borosilicate glass. FIG. 3 is a diagram showing the correlation between the spectral intensity of light to be detected and the presence or absence of cracks in the case of glass for liquid crystal displays.

Hereinafter, preferred embodiments of a laser processing apparatus and a laser processing method according to one aspect of the present disclosure will be described in detail with reference to the drawings.

FIG. 1 is a schematic diagram showing one embodiment of a laser processing apparatus. A laser processing apparatus 1 shown in FIG. 1 is an apparatus that joins a first light-transmitting member S1 and a second light-transmitting member S2 by irradiating a laser beam L1. The laser processing apparatus 1 includes a stage 2 on which a first light-transmitting member S1 and a second light-transmitting member S2, which are objects to be processed, are placed, a light irradiation section 3 for irradiating a laser beam L1 onto the optical member S2; a light detection section 4 for detecting the light to be detected L2 generated by the first light transmissive member S1 and the second light transmissive member S2; and a control unit 5 for controlling the constituent elements of.

The first light-transmitting member S1 and the second light-transmitting member S2 are plate-like members made of, for example, soda lime glass, crystal glass, borosilicate glass, or the like. The first light-transmitting member S1 and the second light-transmitting member S2 may be plate-shaped members made of transparent polyethylene terephthalate, transparent acrylic, transparent polycarbonate, or the like.

The stage 2 is, for example, a stage that can move in three axial directions. A sample stage 6 on which the first light-transmitting member S1 and the second light-transmitting member S2 are placed may be installed on the stage 2 . Further, a pressing plate for pressing the first light-transmitting member S1 and the second light-transmitting member S2 against the sample table 6 may be provided on the stage 2 via an air cylinder or the like. In the example of FIG. 1, the second light-transmitting member S2 is superimposed on the first light-transmitting member S1 on the sample table 6, and the laser beam L1 is irradiated from the side of the second light-transmitting member S2. It is designed to be

The light irradiation unit 3 has a light source 11 that emits laser light L1 and an illumination light 12 that emits illumination light L3. The light source 11 is, for example, a mode-locked regenerative amplified YAG laser. In this case, the laser light L1 emitted from the light source 11 is, for example, pulsed light with a repetition frequency of 50 kHz/wavelength of 1030 nm/pulse width of 10 ps. The spot diameter of the laser beam L1 is, for example, about 3 μm in diameter. The spot diameter can be calculated from the lens used and the beam diameter input to the lens. A laser beam L1 emitted from the light source 11 is reflected by the first dichroic mirror 13 toward the first light-transmitting member S1 and the second light-transmitting member S2 on the stage 2 . After passing through the second dichroic mirror 14 , the laser beam L<b>1 is directed through the condenser lens 15 to the first light-transmitting member S<b>1 and the second light-transmitting member S<b>2 .

The illumination 12 is installed for confirming the irradiation position (processing position) of the laser beam L1 on the first light-transmitting member S1 and the second light-transmitting member S2. An infrared lamp, for example, is used for the illumination 12 . The illumination light L3 emitted from the illumination 12 is reflected by the half mirror 16 toward the first light transmissive member S1 and the second light transmissive member S2 on the stage 2 . After passing through the first dichroic mirror 13, the illumination light L3 passes through the second dichroic mirror 14 coaxially with the laser light L1, and passes through the first light transmissive member S1 and the first light transmissive member S1 together with the laser light L1 through the condenser lens 15. The second light transmissive member S2 is irradiated. The illumination light L3 reflected by the first light-transmitting member S1 and the second light-transmitting member S2 is transmitted through the second dichroic mirror 14, the first dichroic mirror 13, the half mirror 16, and the condenser lens 17. and enters an infrared camera 21, which will be described later.

FIG. 2 is a schematic cross-sectional view showing the state of the first light-transmitting member S1 and the second light-transmitting member S2 during laser light irradiation. As shown in the figure, when the inside of the first light-transmitting member S1 and the second light-transmitting member S2 is irradiated with the laser light L1, multiphotons are generated at the focal point P of the laser light L1 and its vicinity. Absorption (or light absorption equivalent to multiphoton absorption) occurs. Due to this multiphoton absorption, a modified region Sa extending over the first light-transmitting member S1 and the second light-transmitting member S2 is formed. The modified region Sa consists of a melt-solidified region in which the constituent materials of the first light-transmitting member S1 and the second light-transmitting member S2 are melted and solidified, and the first light-transmitting member S1 and the second light-transmitting member S1. It may include an altered region in which the constituent material of the structural member S2 is carbonized.

In the example of FIG. 2, the focal point P of the laser light L1 is located inside the first light transmissive member S1, which is on the side opposite to the irradiation side of the laser light L1. 2 in the vicinity of the contact surface C with the optically transparent member S2. Multiphoton absorption by the laser beam L1 occurs starting from the condensing point P, and the modified region Sa extends from the condensing point P on the side of the first light transmissive member S1 across the contact surface C to the second It is formed so as to reach the inside of the light transmissive member S2. As shown in FIG. 3, by scanning the stage 2 with respect to the laser light L1 and moving the converging point P of the laser light L1 along the planned joining line W from the joining start point Wa to the joining end point Wb, The modified region Sa is formed continuously along the planned joining line W. As shown in FIG. The first light-transmitting member S1 and the second light-transmitting member S2 are fused mainly by the melt-solidified region in the modified region Sa, and are firmly joined to each other without using an intermediate material such as an adhesive. be done. The scanning speed of the stage 2 with respect to the laser beam L1 is, for example, 10 mm/s to 30 mm/s when the repetition frequency of the laser beam L1 is 50 kHz.

The light detection unit 4 has an infrared camera 21 that detects the illumination light L3 and a spectroscope 22 that measures the light spectrum. The infrared camera 21 generates image data corresponding to the detected illumination light L<b>3 and outputs the image data to the control unit 5 . The light to be detected L2 generated by the first light-transmitting member S1 and the second light-transmitting member S2 in response to the irradiation of the laser light L1 is plasma light, for example, and has a white spectrum without a specific peak. . The light to be detected L2 is received by a light receiving lens 23 having a focal point that coincides with the focal point of the condensing lens 15 at the condensing point P. As shown in FIG. In this embodiment, one objective lens 24 is used in common for the condenser lens 15 for condensing the laser beam L1 and the light receiving lens 23 for receiving the light L2 to be detected. As a result, part of the optical path of the laser beam L1 and part of the optical path of the light L2 to be detected are coaxial. The plasma light is radiated in all directions from the generation point, and a part of the components directed toward the light receiving lens 23 is received by the light receiving lens 23 .

The light to be detected L2 received by the light receiving lens 23 is reflected by the second dichroic mirror 14 and separated from the optical paths of the laser light L1 and the illumination light L3. The light to be detected L2 reflected by the second dichroic mirror 14 is reflected by the mirror 25, passes through the ND filter 26, is collected by the lens 27, and enters the spectroscope 22 via the optical fiber . The spectroscope 22 outputs measurement data of the optical spectrum of the light L2 to be detected to the controller 5 .

The control unit 5 is a computer system including a processor, memory, and the like. The control unit 5 executes various control functions by means of a processor. Examples of computer systems include personal computers, microcomputers, cloud servers, and smart devices (smartphones, tablet terminals, etc.). The control unit 5 may be configured by a PLC (programmable logic controller), or may be configured by an integrated circuit such as an FPGA (Field-programmable gate array).

The control unit 5 receives a predetermined input operation, and controls the output of the laser light L1 from the light source 11, the output of the illumination light L3 from the illumination 12, the driving of the stage 2, and the like. Upon receiving the image data from the infrared camera 21, the control unit 5 indicates the irradiation position of the laser light L1 on the first light-transmitting member S1 and the second light-transmitting member S2 based on the received image data. Display the image on a monitor or the like. The control unit 5 also functions as a determination unit 31 that determines whether the processing quality of the first light-transmitting member S1 and the second light-transmitting member S2 is good or bad.

The control unit 5 as the determination unit 31 has a threshold for the intensity of the light L2 to be detected. Based on the measurement data received from the spectroscope 22, the determination unit 31 determines that the intensity of the light L2 to be detected during the irradiation period of the laser light L1 is equal to or greater than the threshold, the first light transmissive member S1 and the second It is judged that the processing quality of the second light transmitting member S2 is normal. If the intensity of the light L2 to be detected during the irradiation period of the laser light L1 is equal to or greater than the threshold value, the determination unit 31 determines that the processing quality of the first light transmissive member S1 and the second light transmissive member S2 is abnormal. We judge that it is.

Also, the control unit 5 may have an allowable range for the intensity of the light L2 to be detected. In this case, when the intensity of the light L2 to be detected during the irradiation period of the laser light L1 is out of the allowable range, the irradiation conditions of the laser light L1 are controlled so that the intensity of the light L2 to be detected falls within the allowable range. The irradiation conditions to be controlled include, for example, the intensity of the laser beam L1, repetition frequency, spot diameter, scanning speed, and the like. In setting the threshold value and the allowable range held by the determination unit 31, the members equivalent to the first light-transmitting member S1 and the second light-transmitting member S2 are processed a plurality of times in advance, and the obtained bonding A cross-section of the modified region Sa in the body is observed respectively. Then, the threshold value and the allowable range are set based on the intensity of the light to be detected L2 during the irradiation period of the laser light L1 when the joined body judged to have normal processing quality is processed.

FIG. 4 is a flow chart showing the operation of the laser processing apparatus 1. As shown in FIG. As shown in FIG. 4, in the laser processing apparatus 1, first, the first light-transmitting member S1 and the second light-transmitting member S2 are set on the stage 2 in a state of being superimposed. Next, the irradiation position of the laser beam L1 coincides with the joining start point Wa, and the condensing point P of the laser beam L1 is located inside the first light-transmitting member S1 and the second light-transmitting member S2. The light irradiation unit 3 is controlled as follows (step S01). After aligning the irradiation position of the laser beam L1 with the joining start point Wa, irradiation of the laser beam L1 and scanning of the stage 2 with respect to the laser beam L1 are started (step S02). Further, the intensity of the light to be detected L2 generated by the first light-transmissive member S1 and the second light-transmissive member S2 in accordance with the irradiation of the laser light L1 is detected (step S03).

During the irradiation period of the laser beam L1, it is determined whether or not the intensity of the light L2 to be detected is within the allowable range (step S04). If it is determined in step S04 that the intensity of the light L2 to be detected is not within the permissible range, the irradiation conditions of the laser beam L1 are controlled so that the intensity of the light L2 to be detected is within the permissible range (step S04). S05). After controlling the irradiation conditions of the laser beam L1, the process returns to step S03 to determine whether the intensity of the light L2 to be detected is within the allowable range. If it is determined in step S04 that the intensity of the light to be detected L2 is not within the allowable range even after repeating the control of the irradiation conditions of the laser beam L1 in step S05 a plurality of times, the first light transmissive member The processing of S1 and the second light transmissive member S2 may be stopped (the output of the laser beam L1 may be stopped).

If it is determined in step S05 that the intensity of the light L2 to be detected is within the allowable range, it is determined whether or not the irradiation position of the laser light L1 has reached the joining end point Wb (step S06). If it is determined in step S06 that the irradiation position of the laser beam L1 has not reached the joining end point Wb, the processes of steps S03 to S05 are repeatedly executed. If it is determined in step S06 that the irradiation position of the laser beam L1 has reached the bonding end point Wb, the irradiation of the laser beam L1 and the scanning of the stage 2 with respect to the laser beam L1 are finished (step S07).

Next, for the first light-transmitting member S1 and the second light-transmitting member S2 that have been processed, it is determined whether or not the intensity of the light to be detected L2 during the irradiation period of the laser light L1 is equal to or greater than the threshold. (Step S08). This determination may be based on a comparison between the time average of the intensity of the light L2 to be detected during the irradiation period of the laser light L1 and a threshold value. It may be based on a comparison of a minimum value and a threshold. When the intensity of the light L2 to be detected during the irradiation period of the laser light L1 is equal to or greater than the threshold, it is determined that the processing quality of the first light transmissive member S1 and the second light transmissive member S2 is normal. (Step S09). When the intensity of the light L2 to be detected during the irradiation period of the laser light L1 is less than the threshold, it is determined that the processing quality of the first light transmissive member S1 and the second light transmissive member S2 is abnormal. (Step S10).

If it is determined that the processing quality of the first light-transmitting member S1 and the second light-transmitting member S2 is normal, the processing quality may be further classified. In this case, for example, the processing quality class determination is performed based on the ratio of the ideal intensity value of the light L2 to be detected during the irradiation period of the laser light L1. For example, when the ideal intensity value of the light L2 to be detected is 100, the intensity of the light L2 to be detected during the irradiation period of the laser light L1 is 90 or more, class A, and 80 or more and less than 90 is class A. B, Class C if it is 70 or more and less than 80. By performing class determination, the first light-transmitting member S1 and the second light-transmitting member S2 that are determined to have normal processing quality are selected for each application. can be classified into

Next, the relationship between the processing quality of the first light-transmitting member S1 and the second light-transmitting member S2 and the intensity of the light L2 to be detected will be described in detail.

The processing quality items determined by the determination unit 31 include, for example, the presence or absence of cracks in the modified region Sa. FIG. 4 is a diagram showing an example of observation results of a cross section of a modified region. FIG. 5(a) is a cross section of the modified region when the processing quality is normal (no cracks). FIG. 5(b) is a cross section of the modified region when the processing quality is abnormal (there are cracks). In the modified region Sa, pulses of the laser light L1 are irradiated to the first light-transmitting member S1 and the second light-transmitting member S2 at narrow pitches temporally and spatially, and multiphoton absorption occurs in the members. is generated, the temperature of the first light-transmitting member S1 and the second light-transmitting member S2 locally reaches the melting temperature. When the laser light L1 is a pulse, it is possible to irradiate the same portion of the member with the pulse multiple times by adjusting the spot diameter, repetition frequency, and scanning speed. As a result, the heating by the next pulse is performed before the heating by the previous pulse is alleviated, and the temperature of the member can be efficiently raised to the melting temperature.

In the example of FIG. 5A, the modified region Sa extends from the focal point P of the laser beam L1 inside the first light-transmitting member S1 beyond the contact surface C to the second light-transmitting member S2. It is formed so as to reach the inside. The modified region Sa gradually widens from the condensing point P toward the second light-transmitting member S2 side, and has a rounded edge on the second light-transmitting member S2 side. The modified region Sa includes an inner region that looks slightly darkened and an outer region surrounding the inner region, and plasma light generated by irradiation with the laser beam L1 is considered to be generated mainly in the inner region. In the example of FIG. 5(b), the shape of the modified region Sa itself is the same as in the case of FIG. 5(a). is occurring. The crack E can be continuously formed along the planned joining line W (see FIG. 3) along with the modified region Sa. Therefore, when the crack E occurs, it is conceivable that the bonding strength between the first light-transmitting member S1 and the second light-transmitting member S2 becomes insufficient.

In order to investigate the relationship between the processing quality of the first light-transmitting member S1 and the second light-transmitting member S2 and the intensity of the light L2 to be detected, the following verification test was conducted to address such problems. carried out. In this verification test, three types of glass, ie, general slide glass, borosilicate glass, and liquid crystal display glass, were prepared as light-transmissive members. S1126 manufactured by Matsunami Glass Co., Ltd. was used as the slide glass, and D263 manufactured by Schott Co., Ltd. was used as the borosilicate glass. Corning NXT was used as the liquid crystal display glass.

FIG. 6 is a diagram showing irradiation conditions of laser light in the verification test. In the verification test, three different types of glass were irradiated with laser light under various irradiation conditions, and the spectrum of the light to be detected during the irradiation period of the laser light was measured. Here, No. 1 to No. A total of 11 types of irradiation conditions were set. The energy, pulse width, aberration correction, and polarization state of the laser light under each irradiation condition are as shown in FIG.

FIG. 7 is a diagram showing the result of measuring the spectral intensity of the light to be detected when the slide glass was processed by the ultraviolet region measurement system. FIG. 8 is a diagram showing the result of measuring the spectral intensity of the light to be detected when the slide glass was processed by the visible range measurement system. 7 and 8, the horizontal axis indicates wavelength and the vertical axis indicates intensity (arbitrary unit). 1 to No. All 11 measurement results are superimposed. From the results of FIGS. 7 and 8, no specific peak was observed in the spectral intensity of the light to be detected between the irradiation conditions, regardless of whether the ultraviolet range measurement system or the visible range measurement system was used. It can be seen that only the intensity fluctuates while maintaining the spectral waveform of the light. Therefore, it can be seen that a wavelength having a relatively high spectral intensity should be selectively used for the judgment of the processing quality in the judging section.

9 and 10 are diagrams showing the correlation between the spectral intensity of the light to be detected and the presence or absence of cracks. In FIGS. 9 and 10, the horizontal axis indicates the irradiation condition number. , and the spectrum intensity is shown on the left side of the vertical axis. 9 shows spectral intensity in the ultraviolet region (wavelength 430 nm), and FIG. 10 shows spectral intensity in the visible region (wavelengths 570 nm, 615 nm, and 670 nm). 9 and 10, the size of the modified region is shown on the right side of the vertical axis. W _OUT is the maximum width of the modified region including the outer region, and H _OUT is the maximum height of the modified region including the outer region (see FIG. 4).

In the results of FIGS. 9 and 10, the irradiation condition No. indicated by the dashed line area. 4 to No. 8, no cracks occurred in the modified region, and irradiation condition No. 8 outside the broken line region. 1 to No. 3 and irradiation condition No. 9 to No. In No. 11, cracks were generated in the modified region. In the measurement in the ultraviolet region, irradiation condition No. 1 under which no cracks occurred in the modified region. 4 to No. 8, the spectral intensity of the light to be detected was 2500 or more, and under irradiation condition No. 8 cracks were generated in the modified region. 1 to No. 3 and irradiation condition No. 9 to No. 11, the spectral intensity of the light to be detected was all less than 2500. In addition, even in the measurement in the visible range, irradiation condition No. 1 under which no cracks occurred in the modified region. 4 to No. 8, irradiation condition No. 8 under which cracks occurred in the modified region. 1 to No. 3 and irradiation condition No. 9 to No. 11, the spectral intensity of the light to be detected at each wavelength was higher.

From the above, it can be seen that crack generation in the modified region tends to be suppressed when the spectral intensity of the light to be detected is higher than a certain level. On the other hand, the correlation between the spectral intensity and the size of the modified region and the correlation between the size of the modified region and crack generation could not be confirmed. No significant difference was found in the correlation between the spectral intensity of the detected light and the presence or absence of cracks between the measurement in the ultraviolet region and the measurement in the visible region.

FIG. 11 shows the correlation for borosilicate glass, and FIG. 12 shows the correlation for liquid crystal display glass. 11 and 12 are both measurement results of the visible region. In the results of FIG. 11, irradiation condition No. 1 indicated by the dashed line area. Only No. 10 had cracks in the modified region. This irradiation condition No. 10, the spectral intensity of the detected light was less than 200. Of the irradiation conditions under which cracks did not occur in the modified region, No. 2 and No. In No. 3, the spectral intensity of the light to be detected was less than 200, but the spectral intensity of the light to be detected was 200 or more under all other irradiation conditions. In addition, a certain correlation was observed between the spectral intensity and the size of the modified region compared to the slide glass.

In the results of FIG. 12, the irradiation condition No. indicated by the dashed line area. 4 to No. 6, no cracks occurred in the modified region, and irradiation condition No. 6 outside the broken line region. 1 to No. 3 and irradiation condition No. 7 to No. In No. 11, cracks were generated in the modified region. On the other hand, the correlation between the spectral intensity and the size of the modified region and the correlation between the size of the modified region and crack generation could not be confirmed.

As described above, in the laser processing apparatus 1, the light to be detected L2 generated by the first light-transmitting member S1 and the second light-transmitting member S2 in response to the irradiation of the laser light L1 by the light irradiation unit 3 The intensity is detected by the photodetector 4 . In this laser processing apparatus 1, the intensity of the light to be detected L2 generated by the first light-transmitting member S1 and the second light-transmitting member S2 during the irradiation period of the laser light L1 and the formation state of the modified region Sa are The intensity of the detected light L2 can be used as an index of processing quality based on a certain correlation that exists between . Therefore, the machining quality can be objectively evaluated without relying on visual observation, and the reliability of the machining quality can be improved.

In addition, the laser processing apparatus 1 has a threshold for the intensity of the light L2 to be detected, and determines whether the intensity of the light L2 to be detected during the irradiation period of the laser light L1 is equal to or greater than the threshold. A judging section 31 is provided for judging whether the processing quality of the optical member S1 and the second optically transparent member S2 is good or bad. Accordingly, it is possible to more objectively judge the quality of processing of the first light-transmitting member S1 and the second light-transmitting member S2 based on the intensity of the light L2 to be detected.

In addition, the laser processing apparatus 1 has an allowable range for the intensity of the light L2 to be detected. is within the allowable range. As a result, the irradiation of the laser beam L1 is performed under the condition that the intensity of the light L2 to be detected falls within the allowable range, so that the processing yield of the first light-transmitting member S1 and the second light-transmitting member S2 is improved. can.

In the laser processing apparatus 1, the light irradiation section 3 has a condenser lens 15 for condensing the laser light L1, and the light detection section 4 has a light receiving lens 23 for receiving the light L2 to be detected. The focal point of the condensing lens 15 and the focal point of the light receiving lens 23 coincide at the condensing point P. As shown in FIG. Thereby, the light to be detected generated near the condensing point P can be efficiently detected. In this embodiment, the condenser lens 15 and the light receiving lens 23 are shared by one objective lens 24 to simplify the configuration.

The present disclosure is not limited to the above embodiments. In the above-described embodiment, the spectroscope 22 is used in the photodetector 4 to measure the spectral intensity of the light L2 to be detected in the ultraviolet region and the visible region. The spectral intensity of L2 may be measured. In this case, a photodiode can be used instead of the spectroscope 22 . In the above-described embodiment, the objective lens 24 is used to share the condenser lens 15 and the light receiving lens 23, and part of the optical path of the laser beam L1 and part of the optical path of the light L2 to be detected are coaxial. common lens is not essential. For example, the stage 2 may be made of a material having optical transparency to the light L2 to be detected, and the optical system after the light receiving lens 23 may be arranged behind the stage 2 to detect the light L2 to be detected.

DESCRIPTION OF SYMBOLS 1... Laser processing apparatus 3... Light irradiation part 4... Light detection part 5... Control part 15... Condensing lens 23... Light receiving lens 24... Objective lens 31... Judgment part S1... First light Transmissive member S2 Second light transmissive member L1 Laser light L2 Light to be detected C Contact surface P Condensing point Sa Modified region.

Claims (10)

A laser processing apparatus for joining a first light-transmitting member and a second light-transmitting member by irradiating a laser beam,
In the vicinity of the contact surface of the first light-transmitting member and the second light-transmitting member, the laser beam is irradiated with the focal point aligned with the inside of one of these members, and the first light transmission is performed. a light irradiation section forming a modified region extending over the optical member and the second light transmissive member;
a light detection unit that detects the intensity of light to be detected generated by the first light-transmitting member and the second light-transmitting member in response to irradiation of the laser light by the light irradiation unit. Device. Having a threshold value for the intensity of the light to be detected, the first light transmissive member and the second light transmitting member determine whether or not the intensity of the light to be detected during the irradiation period of the laser light is equal to or higher than the threshold value. 2. The laser processing apparatus according to claim 1, further comprising a judging section for judging whether the processing quality of said light transmissive member is good or bad. An allowable range for the intensity of the light to be detected is provided, and when the intensity of the light to be detected during the irradiation period of the laser beam deviates from the allowable range, the intensity of the light to be detected falls within the allowable range. 3. The laser processing apparatus according to claim 1, further comprising a control section for controlling irradiation conditions of said laser beam. The light irradiation unit has a condenser lens for condensing the laser beam,
The light detection unit has a light receiving lens that receives the light to be detected,
4. The laser processing apparatus according to any one of claims 1 to 3, wherein the focus of said condensing lens and the focus of said light receiving lens are aligned at said condensing point. 5. A laser processing apparatus according to claim 4, wherein said condenser lens and said light receiving lens are shared by one objective lens. A laser processing method for joining a first light-transmitting member and a second light-transmitting member by irradiating a laser beam,
In the vicinity of the contact surface of the first light-transmitting member and the second light-transmitting member, the laser beam is irradiated with the focal point aligned with the inside of one of these members, and the first light transmission is performed. a light irradiation step of forming a modified region over the optical member and the second light transmissive member;
and a light detection step of detecting the intensity of the light to be detected generated by the first light-transmitting member and the second light-transmitting member in response to the irradiation of the laser light by the light irradiation unit. Method. Having a threshold value for the intensity of the light to be detected, the first light transmissive member and the second light transmitting member determine whether or not the intensity of the light to be detected during the irradiation period of the laser light is equal to or higher than the threshold value. 7. The laser processing method according to claim 6, further comprising a judgment step of judging whether the processing quality of the light transmissive member is good or bad. An allowable range for the intensity of the light to be detected is provided, and when the intensity of the light to be detected during the irradiation period of the laser beam deviates from the allowable range, the intensity of the light to be detected falls within the allowable range. 8. The laser processing method according to claim 6 or 7, further comprising a control step of controlling irradiation conditions of said laser light so as to control the irradiation conditions. In the light irradiation step, the laser light is condensed by a condensing lens,
In the light detection step, the light to be detected is received by a light receiving lens,
9. The laser processing method according to any one of claims 6 to 8, wherein the focus of the condenser lens and the focus of the light-receiving lens are matched at the condenser point. 10. The laser processing method according to claim 9, wherein the condenser lens and the light receiving lens are shared by one objective lens.

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