Laser device

Abstract

A laser device includes: a laser light source that emits laser light; a phase control section that controls a spatial phase of a part of the laser light emitted from the laser light source and emits the part as control light, and emits another part of the laser light as non-control light; a first optical system that irradiates the control light emitted from the phase control section to an object; a detector that detects the non-control light emitted from the phase control section; a second optical system that condenses the non-control light emitted from the phase control section toward a detection surface of the detector; and a control section that controls the phase control section in a manner to correct a control state of the spatial phase of the control light in the phase control section based on a detection result of the non-control light from the detector.

Description

Technical Field

[0001] This invention relates to a laser device. Background Technology

[0002] Patent Document 1 describes a laser processing apparatus. This apparatus includes a focusing lens, a variable focus lens, a focusing position measuring unit, a focusing position control unit, an optical system, and a light source. The focusing lens focuses the laser light supplied by the light source onto the surface of the object to be processed. The laser light supplied by the light source is optically shaped by the optical system via an optical fiber and then focused by the focusing lens. The variable focus lens is positioned in the optical path of the focusing lens. The focal distance of the variable focus lens can be changed by applying a voltage. The focusing position measuring unit measures the focusing position of the focusing lens using light extracted through a semi-reflective mirror.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2020-040072 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] In the laser processing apparatus described in Patent Document 1, the focusing position control unit controls the focal position of the variable focal lens within a set allowable range by using the difference between the focusing position measured by the focusing position measuring unit and a predetermined focusing position as the set allowable range. This aims to maintain the initial focal position.

[0008] However, for the aforementioned laser processing apparatus, for example, to increase processing speed, a phase controller using a liquid crystal spatial phase modulator (e.g., LCOS-SLM) is considered to branch the laser beam into multiple segments. In this case, if the focusing position changes as the laser processing apparatus operates, feedback control of the phase controller is considered to correct for this change. In this case, if the change in the focusing position can be detected as originating from a change in the light source, the control of the phase controller is simpler. However, in the aforementioned laser processing apparatus, because a semi-reflective mirror guides the entire laser beam to the focusing position measuring unit, it is difficult to detect whether the change in the focusing position is caused by a change in the light source or by a change caused by the phase controller or other optical systems.

[0009] Therefore, the object of the present invention is to provide a laser device that can easily correct changes in the focusing state.

[0010] Technical means to solve the problem

[0011] To address the aforementioned problems, the inventors conducted in-depth research and obtained the following insights. Specifically, in phase controllers such as spatial phase modulators, a portion of the incident laser light is phase-controlled and emitted as control light to irradiate an object, while another portion is not phase-controlled and emitted as uncontrolled light. Because this uncontrolled light does not undergo the desired phase control, it tends to be treated as loss or noise. However, on the other hand, because it is less affected by the phase controller, it retains the characteristics of the laser light at the point of emission from the light source. Therefore, by detecting this uncontrolled light, changes in the focusing state caused by the light source can be detected, and these changes can be easily corrected through feedback control of the phase controller. This invention was completed based on these insights through repeated and further research by the inventors.

[0012] That is, the laser device of the present invention comprises: a laser source that emits laser light; a phase control unit that receives the laser light emitted from the laser source, controls the spatial phase of a portion of the laser light and emits it as control light, and emits another portion of the laser light as uncontrolled light; a first optical system that illuminates an object with the control light emitted from the phase control unit; a detector that detects the uncontrolled light emitted from the phase control unit; a second optical system that focuses the uncontrolled light emitted from the phase control unit toward the detection surface of the detector; and a control unit that performs correction processing of the phase control unit in such a way as to correct the control state of the spatial phase of the control light in the phase control unit based on the detection result of the uncontrolled light from the detector.

[0013] In this laser device, a portion of the laser emitted from the laser source has its spatial phase controlled by a phase control unit and is used as control light, which is then supplied to an object via a first optical system. On the other hand, another portion of the laser emitted from the laser source is used as uncontrolled light and is focused onto the detection surface of the detector via a second optical system. Thus, the uncontrolled light emitted from the laser source that is not controlled by the phase control unit is detected. As described above, this uncontrolled light is less susceptible to influence from the phase control unit, maintaining the characteristics of the laser at the point of emission from the light source. Therefore, by controlling the phase control unit to correct the spatial phase control state of the control light in the phase control unit based on the detection result of this uncontrolled light, changes in the focusing state of the laser (control light) caused by the light source can be easily corrected.

[0014] As a result, even when the characteristics of the laser emitted from the laser source change due to variations over time, the focusing state of the laser illuminating the object can be easily maintained at a specific initial value. Particularly when multiple laser devices are used in parallel, if this specific initial value is common to all laser devices, then even if the focusing state of the laser emitted from the laser source varies for each laser device, the focusing state of the laser in each laser device will be maintained at a common initial value, thus reducing mechanical variability. Therefore, because this laser device can achieve a reduction in mechanical variability, it is effective even when multiple devices are used in parallel.

[0015] In the laser device of the present invention, the control unit may also perform the following processes: a first acquisition process, which, based on the detection result, acquires the deviation amount of the position of the uncontrolled light in the plane intersecting the optical axis direction of the uncontrolled light, i.e., a first deviation amount; and a first correction process, which, as a correction process, controls the phase control unit to correct the position deviation of the control light in the plane intersecting the optical axis direction of the control light based on the first deviation amount. In this case, based on the information related to the position deviation in the plane intersecting the optical axis direction of the uncontrolled light, the position deviation in the plane intersecting the optical axis direction of the control light can be easily corrected.

[0016] In the laser device of the present invention, the control unit may also perform the following processes: a second acquisition process, which acquires the diffusion angle of the non-control light based on the detection result; and a second correction process, which, as a correction process, controls the phase control unit in a manner that corrects the diffusion angle of the control light based on the diffusion angle. In this case, the change in the diffusion angle of the control light can be easily corrected based on information related to the amount of change in the diffusion angle of the non-control light.

[0017] In the laser device of the present invention, the control unit may also, in the second acquisition process, obtain the deviation amount, i.e., the second deviation amount, of the position where the uncontrolled light is most focused on the detection surface from the initial position by driving the detector along the optical axis direction of the uncontrolled light while detecting the uncontrolled light, and obtain the diffusion angle based on the second deviation amount. In this case, information related to the change in the diffusion angle of the uncontrolled light can be obtained based on the mechanical drive of the detector.

[0018] In the laser device of the present invention, the phase control unit may also include: a polarization control element that changes the polarization direction of the laser and emits it such that the input laser contains both S-polarization and P-polarization components; and a liquid crystal spatial phase modulator that controls the spatial phase of the P-polarization component of the laser emitted from the polarization control element and emits it as control light, while emitting the S-polarization component of the laser as uncontrolled light. In the correction process, the control unit adjusts the phase modulation pattern displayed on the liquid crystal spatial phase modulator based on the detection result of the uncontrolled light, thereby correcting the control state of the spatial phase of the control light in the phase control unit. Thus, when the phase control unit includes a liquid crystal spatial phase modulator, if the polarization direction is adjusted so that the laser contains both P-polarization and S-polarization, the S-polarization component, which is insensitive to the liquid crystal layer, is appropriately used as uncontrolled light, and by adjusting the phase modulation pattern (hologram) displayed on the liquid crystal layer, changes in the focusing state of the control light can be easily corrected.

[0019] In the laser device of the present invention, the phase control unit may also include a liquid crystal spatial phase modulator, which displays a phase modulation pattern for branching the input laser into multiple diffracted beams and emitting them, thereby emitting the 0th order laser light as uncontrolled light and emitting the other orders of diffracted laser light as control light; in the correction process, the control unit adjusts the phase modulation pattern displayed on the liquid crystal spatial phase modulator based on the detection result of the uncontrolled light, thereby correcting the control state of the spatial phase of the control light in the phase control unit. Thus, when the liquid crystal spatial phase modulator is included, and the laser is branched into multiple beams by diffraction, the undiffracted 0th order light is appropriately used as uncontrolled light, and by adjusting the phase modulation pattern (hologram) displayed on the liquid crystal layer, changes in the focusing state of the control light can be easily corrected.

[0020] The laser device of the present invention may also include other detectors for detecting control light emitted from the phase control unit, and the control unit generates a phase modulation pattern for adjusting the spatial phase of the control light in the phase control unit based on the detection results of the control light from the other detectors, and superimposes this phase modulation pattern onto a phase modulation pattern adjusted by correction processing and displays it on a liquid crystal spatial phase modulator. In this case, based on the detection results of the control light, the control state of the control light can be adjusted according to changes in the laser (control light) caused by factors other than the light source.

[0021] The effects of the invention

[0022] According to the present invention, a laser device that can easily correct changes in the focusing state can be provided. Attached Figure Description

[0023] Figure 1 This is a block diagram of a laser processing apparatus according to one embodiment.

[0024] Figure 2 yes Figure 1 The diagram shows a schematic of a laser processing device.

[0025] Figure 3 It is a display Figure 1 , 2 The diagram shows the camera surface of the second detector.

[0026] Figure 4 It is a graph showing the detection of the focusing position of the uncontrolled light.

[0027] Figure 5 This is a flowchart showing the laser correction method.

[0028] Figure 6 It is an image showing the camera surface of the second detector.

[0029] Figure 7 It is an image showing the camera surface of the first detector.

[0030] Figure 8 It is an image showing the camera surface of the second detector.

[0031] Figure 9 It is an image showing the camera surface of the second detector.

[0032] Figure 10 It is an image showing the camera surface of the first detector.

[0033] Figure 11 It is an image showing the camera surface of the first detector.

[0034] Figure 12 This is a diagram used to illustrate an example of coordinate transformation.

[0035] Figure 13 This is a graph based on the second deviation of various indicators.

[0036] Figure 14 This is a diagram showing the corrective control of the light.

[0037] Figure 15 This is a diagram showing the corrective control of the light.

[0038] Figure 16 This is a block diagram of a modified laser processing apparatus.

[0039] Figure 17 yes Figure 16 The diagram shows a schematic of a laser processing device.

[0040] Figure 18 It is a diagram used to illustrate the polarization direction of laser light.

[0041] Figure 19 This is a schematic diagram showing the phase control unit of a modified example.

[0042] Figure 20 It is a display Figure 19 A diagram showing a modified example of the phase control unit. Detailed Implementation

[0043] Hereinafter, a detailed description of one embodiment will be given with reference to the accompanying drawings. Furthermore, in the drawings, the same or equivalent parts are labeled with the same symbols, and repeated descriptions are omitted. Figure 1 This is a block diagram of a laser processing apparatus according to one embodiment. Figure 2 yes Figure 1 The diagram shows a schematic of a laser processing device. Figure 1 , 2 The laser processing apparatus (laser device) 100 shown is used as an example to perform perforation, cutting, and micro-processing of semiconductors and the like on an object A by irradiating the object A with a laser.

[0044] The laser processing apparatus 100 includes a laser source 10, a phase control unit 20, a first optical system 30, a first detector 40, a second detector 50, and a control unit 60. The laser source 10 emits a laser L1. The phase control unit 20 includes a spatial phase modulator (liquid crystal type spatial phase modulator) 21 and a mirror 22 that guides the laser L1 onto the spatial phase modulator 21. The spatial phase modulator 21 has a liquid crystal layer, and by displaying an arbitrary phase modulation pattern (hologram, CGH (Computer Generated Hologram)) on the liquid crystal layer under the control of the control unit 60, the spatial phase of the laser L1 is controlled according to the phase modulation pattern.

[0045] A portion of the laser light L1 incident on the spatial phase modulator 21 has its spatial phase controlled and is emitted from the spatial phase modulator 21. On the other hand, another portion of the laser light L1 incident on the spatial phase modulator 21 has its spatial phase uncontrolled and is emitted from the spatial phase modulator 21. That is, the phase control unit 20 is used to input the laser light L1 emitted from the laser source 10, control the spatial phase of a portion of the laser light L1 and emit it as control light L2, and emit the other portion of the laser light L1 as uncontrolled light L3.

[0046] The first optical system 30 is used to guide the control light L2 emitted from the phase control unit 20 and illuminate the object A. The first optical system 30 includes mirrors 31, 32, and 33 that guide the control light L2 emitted from the spatial phase modulator 21 toward the object A. The control light L2 and the non-control light L3 are sequentially reflected by the respective mirrors 31, 32, and 33 and illuminate the object A. Furthermore, the first optical system 30 includes lenses 80, 34, and 35 sequentially arranged in the optical paths of the control light L2 and the non-control light L3 formed through the mirrors 31, 32, and 33. Lenses 80 and 34 are used to image the image of the control light L2 from the spatial phase modulator 21 onto lens 35. Lens 35 faces the object A and is a focusing lens for concentrating the control light L2 toward the object A.

[0047] The first detector (other detectors) 40 is, for example, a camera used to capture the control light L2, and can be used to detect changes in the characteristics of the control light L2 under the control of the control unit 70. The detection result of the first detector 40 can be used, for example, for feedback control of the control light L2 caused by the phase control unit 20. Details of this feedback control will be described later. In addition, the non-control light L3 can also be incident on the first detector 40 in addition to the control light L2. Therefore, the first detector 40 can also capture the non-control light L3. The first detector 40 is, for example, positioned on the extension line of the optical path of the control light L2 and the non-control light L3 from the mirror 32 toward the mirror 33, and captures a portion of the control light L2 (and the non-control light L3) that is imaged onto the imaging surface 40s through the mirror 33. On the imaging surface 40s of the first detector 40, an image corresponding to the processed surface of the object A is formed.

[0048] The second detector 50 (detector) is, for example, a camera used to capture the uncontrolled light L3, and can be used to detect changes in the characteristics of the uncontrolled light L3 under the control of the control unit 60. The detection result of the second detector 50 can be used, for example, for feedback control of the uncontrolled light L3 caused by the phase control unit 20. Details of this feedback control will be described later. In addition, the control light L2 can also be incident on the second detector 50 in addition to the control light L3. Therefore, the second detector 50 can also capture the control light L2. The second detector 50 is here positioned on the extension line of the optical path of the uncontrolled light L3 (and control light L2) from the mirror 31 toward the mirror 32, and captures a portion of the uncontrolled light L3 (and control light L2) that is imaged onto the imaging surface 50s (detection surface) through the mirror 32. In addition, the lens 80 is also a second optical system for focusing the uncontrolled light L3 (and control light L2) toward the imaging surface 50s.

[0049] Figure 3 It is a display Figure 1 , 2The diagram shows the imaging surface of the second detector. Here, as an example, by displaying a phase modulation pattern containing a diffraction grating pattern on the spatial phase modulator 21, the laser L1 branches into multiple diffracted beams, forming multiple beam spots on the imaging surface 50s. Figure 3 In example (a), a beam point of uncontrolled light L3 with zero order light is formed at the center, and a beam point of controlled light L2 with one order light is formed around it. Additionally, in Figure 3 In example (a), the control light L2 and the non-control light L3 are focused onto the imaging surface 50s by setting the distance Z between the lens 80 and the imaging surface 50s as the focal distance fm of the lens 80.

[0050] In contrast, if the phase modulation pattern of the spatial phase modulator 21 overlaps with the pattern of a specific Fresnel lens, and the second detector 50 (image plane 50s) moves in the optical axis direction by the amount of positional offset from the focal distance fm caused by increasing the focal distance fFL of the Fresnel lens, then as Figure 3 As shown in (b), the control light L2, which is controlled by the spatial phase modulator 21, is focused onto the imaging surface 50s. On the other hand, the uncontrolled light L3, which is not controlled by the spatial phase modulator 21, deviates from the focal distance fFL from the imaging surface 50s at its focusing position and amplifies the beam spot. On the other hand, as... Figure 3 As shown in (c), if the camera surface returns to its original position after 50 seconds... Figure 3 At position (a), the focusing position of the control light L2 deviates from the focal distance fFL of the Fresnel lens from the imaging surface 50s and amplifies the beam point. On the other hand, the non-control light L3 focuses on the imaging surface 50s as before.

[0051] The position of the optical axis of the imaging surface 50s (distance Z0 between lens 80 and imaging surface 50s) of the non-controlled light L3 focusing beam can be detected, for example, as follows. That is, as Figure 4 As shown in the graph, the distance Z0 is obtained by moving the imaging surface 50s of the second detector 50 in the optical axis direction while capturing the uncontrolled light L3 and obtaining the detection result. For example, it can be obtained as the value where the intensity of the uncontrolled light L3 is at its maximum value I0, or the value where the spot size of the uncontrolled light L3 on the imaging surface 50s is at its minimum value W0. These phase control unit 20 and the control and light detection processes of the second detector 50 can be implemented by the control unit 60. The same control and light detection processes for the control light L2 can be implemented by the control unit 70. Furthermore, the control unit 60 and the control unit 70 can also perform different controls on the first detector 40 and the second detector 50 respectively. That is, regarding the control light L2, the control unit 70 can also implement different control and light detection processes than for the uncontrolled light L3.

[0052] That is, the control unit 60 can control at least the phase control unit 20 and the second detector 50. Additionally, the control unit 70 can control at least the phase control unit 20 and the first detector 40. The control unit 60 performs processing to control the phase control unit 20 in a manner that corrects the spatial phase state of the control light L2 in the phase control unit 20 based on the detection result of the non-control light L3 from the second detector 50. Furthermore, the control unit 70 performs processing to control the phase control unit 20 in a manner that corrects the spatial phase state of the control light L2 in the phase control unit 20 based on the detection result of the control light L2 from the first detector 40. These processes will be described in detail later. The control units 60 and 70 have a processing unit, a storage unit, and an input receiving unit (not shown). The processing unit is configured as a computer device including a processor, memory, storage, and communication devices. In the processing unit, the processor executes software (programs) read into the memory, etc., and controls the reading and writing of data in the memory and storage, as well as communication of the communication devices. The storage unit is, for example, a hard disk, which stores various types of data. The input reception department is an interface department that displays various information and accepts various information inputs from users.

[0053] Next, the laser correction method implemented by the laser processing apparatus 100 will be explained, and the details of the operation of the control unit 60 will be described. This method is implemented by the control unit 60 executing various processes. Figure 5 This is a flowchart of the laser correction method. The control unit 60 stores information about the initial state of the display laser processing apparatus 100 in advance. For example, the information related to the initial state stored by the control unit 60 includes the initial values ​​of the position (coordinates), spot size (beam area), and brightness of the non-control light L3 on the imaging surface 50s, or the position (coordinates), spot size (beam area), and brightness of the control light L2 on the imaging surface 40s.

[0054] Here, firstly, the control unit 60 measures the displacement from the initial position (process S1). More specifically, the control unit 60 performs a first acquisition process, which involves capturing the uncontrolled light L3 through the second detector 50 and obtaining the first deviation amount, which is the amount of deviation of the current position of the uncontrolled light L3 from the initial position within the plane (here, the imaging plane 50s, sometimes referred to as the "XY plane") intersecting the optical axis of the uncontrolled light L3. Figure 6 (a) shows the state of the beam point of the uncontrolled light L3 at the initial position (x, y) on the XY plane. Figure 6 (b) shows the position (x+Δx, y+Δy) of the beam point of the uncontrolled light L3 on the XY plane, which is a displacement from the initial position (x, y). That is, here, Δx and Δy are taken as the first deviation. As an example, Δx = +47 pixels and Δy = -26 pixels. This deviation may occur, for example, over many years.

[0055] Figure 7 It is an image showing the camera surface 40s of the first detector 40. Figure 7 (a) shows the state where the beam point of control light L2 is in its initial position. For example... Figure 7 As shown in (b), if the non-control light L3 deviates from its initial position in the XY plane, then similarly, the control light L2 deviates in the plane intersecting the optical axis. The deviations Δu and Δv on the imaging plane over 40 seconds are, as an example, Δu = +18 pixels and Δv = -10 pixels. Figure 6 , 7 As shown, since the control light L2, which is controlled by the phase control unit 20, deviates, and on the other hand, the uncontrolled light L3, which is not controlled by the phase control unit 20, also deviates, it should be understood that the deviation includes at least the deviation caused by the laser source 10 on the front side of the phase control unit 20.

[0056] In this process S1, a second acquisition process is further performed, in which the control unit 60 uses the second detector 50 to capture the uncontrolled light L3 and obtain the displacement of the diffusion angle of the uncontrolled light L3 from the initial position. Figure 8 (a) is an image showing the initial state of the beam point on the XY plane of the uncontrolled light L3. Figure 8 (b) is Figure 8 An enlarged view of (a). On the other hand, Figure 9 (a) is an image showing the changes in the beam point of the uncontrolled light L3 in the XY plane from its initial state. Figure 9 (b) is Figure 9 An enlarged view of (a). For example... Figure 8 , 9 As shown, here, the diffusion angle of the uncontrolled light L3 changes within the XY plane. Additionally, in... Figure 8 , 9 In the image, points drawn by the software to detect beam points are displayed on the outer periphery of the beam points.

[0057] Based on the detection results (image) of the second detector 50, the control unit 60 obtains the change ΔS of the spot size in the XY plane of the uncontrolled light L3 from the initial value S, and / or the change ΔI of the intensity in the XY plane of the uncontrolled light L3 from the initial value I. These changes ΔS and ΔI become indicators of the diffusion angle of the uncontrolled light L3.

[0058] in addition, Figure 10 It is an image showing the camera surface 40s of the first detector 40. Figure 10 (a) is an image showing the beam point of the control light L2 in its initial state. Figure 10 (b) is Figure 10 An enlarged view of (a). On the other hand, Figure 11 (a) is an image showing the state of the beam point of the control light L2 as it changes from its initial state. Figure 11 (b) is Figure 11 An enlarged view of (a). For example... Figure 10 , 11 As shown, here, the diffusion angle of the control light L2 also changes.

[0059] like Figures 8-11 As shown, if the diffusion angle of the uncontrolled light L3 changes, the same applies to the diffusion angle of the control light L2. Since the diffusion angle of the control light L2, which is controlled by the phase control unit 20, changes, and the diffusion angle of the uncontrolled light L3, which is not controlled by the phase control unit 20, also changes, it should be understood that this change includes at least the change caused by the laser source 10.

[0060] In the subsequent process, the control unit 60 converts the coordinates (x+Δx, y+Δy) on the XY plane (image plane 50s) of the uncontrolled light L3, which includes Δx and Δy as the first deviation amount, into coordinates displayed on the hologram of the spatial phase modulator 21 (hereinafter referred to as "coordinates on the UV plane") (process 2). Figure 12 This is a diagram illustrating an example of coordinate transformation. The transformation of the scale s between the coordinates on the XY plane and the coordinates on the UV plane is shown by the following equation (1), and the transformation of the angle θ is shown by the following equation (2). Therefore, the coordinates between the coordinates on the XY plane and the coordinates on the UV plane are transformed by the following equation (3). As an example, when the coordinates on the XY plane of the uncontrolled light L3 are set as (x1, y1), the coordinates on the UV plane of the uncontrolled light L3 are calculated as (u1, 0).

[0061] [Number 1]

[0062]

[0063] [Number 2]

[0064]

[0065] [Number 3]

[0066]

[0067] In subsequent processes, the control unit 60 determines whether the state change of the uncontrolled light L3 is within the allowable range (process S3). More specifically, the control unit 60 determines whether the change ΔS of the spot size of the uncontrolled light L3 in the XY plane obtained in process S1 from the initial value S, and / or whether the change ΔI of the intensity of the uncontrolled light L3 in the XY plane from the initial value I is within the allowable range. That is, here, as an example, it determines whether the diffusion angle is within the allowable range.

[0068] If the state change of the uncontrolled light L3 is not within the allowable range according to the determination of process S3 (process S3: No), the control unit 60 obtains the diffusion angle of the uncontrolled light L3 on the XY plane (process S4, second acquisition process). More specifically, the control unit 60 first detects the uncontrolled light L3 through the second detector 50 while driving the second detector 50 along the optical axis direction of the uncontrolled light L3, thereby obtaining the deviation amount of the uncontrolled light L3 from the initial position of the most focused position on the imaging surface 50s, i.e., the second deviation amount.

[0069] Figure 13 This chart is based on the scenario where various indicators reach a second deviation. Additionally, in... Figure 13 In the middle, the horizontal axis shows the relative position (i.e., the second deviation) of the second detector 50 (camera) in the optical axis direction from its initial position. Figure 13 (a) uses the peak brightness of the uncontrolled light L3 as an indicator. Figure 13 (b) is indicated by the brightness density of the uncontrolled light L3. In these cases, since the maximum value of each index can be obtained by moving the second detector 50 in the optical axis direction, the relative position of this maximum value is obtained as the second deviation.

[0070] on the other hand, Figure 13 (c) is indicated by the spot size (beam area). In this case, its minimum value can be obtained by moving the second detector 50 in the optical axis direction. The relative position at which this minimum value is obtained is called the second deviation. Here, even in any case, the same second deviation as 1.5 mm is obtained. The second deviation is the amount by which the focal position of the non-control light L3 is offset in the optical axis direction.

[0071] Furthermore, here, the control unit 60 calculates the diffusion angle of the uncontrolled light L3 based on the obtained second deviation. The diffusion angle is calculated as the focal distance fFL of the Fresnel lens corresponding to the second deviation. The focal distance fFL corresponding to the second deviation is obtained by the following formula. Specifically, the following formula (4) is related to the focal distance f0 of the composite lens of the Fresnel lens and the lens 80 implemented by the CGH displayed on the spatial phase modulator 21, and the following formulas (5) and (6) transform the following formula (4) into the formula for the focal distance fFL of the Fresnel lens. In addition, d in the following formula is the distance between the lens 80 and the Fresnel lens.

[0072] [Number 4]

[0073]

[0074] [Number 5]

[0075]

[0076] [Number 6]

[0077]

[0078] In contrast, since the second deviation (the offset of the focal position) obtained as described above is set as Δd, then f0 = fm + Δd. Therefore, if this is introduced into the above equation (6), the focal distance fFL of the corresponding Fresnel lens is expressed as the following equation (7), and if further modified, it is obtained as the following equation (8). As an example, when Δd is 1.5mm as described above, the corresponding focal distance fFL of the Fresnel lens is 62570mm.

[0079] [Number 7]

[0080]

[0081] [Number 8]

[0082]

[0083] Furthermore, if the result of step S3 indicates that the state change of the uncontrolled light L3 is within the allowable range (step S3: Yes), the control unit 60 sets the diffusion angle of the uncontrolled light L3 to 0, that is, sets the focal distance fFL of the Fresnel lens to infinity (step S5), and proceeds to the subsequent step S6. Setting the focal distance fFL of the Fresnel lens to infinity means that no Fresnel lens component is added when generating the correction CGH. In the above example, a positive diffusion angle is shown (a change in the diverging direction occurs), but a negative diffusion angle also exists (a change in the convergent direction occurs).

[0084] In a subsequent process, the control unit 60 generates a CGH (process S6) to correct for changes in the state as described above. More specifically, the control unit 60 generates a CGH with an overlaid pattern, the pattern including parameters (-Δu, -Δv, -fFL) for canceling out the first deviation amount, Δx and Δy, obtained as described above, and the focal distance fFL of the Fresnel lens, which is the diffusion angle, corresponding to the second deviation amount. The control unit 60 displays the generated CGH on the spatial phase modulator 21. Thus, by using the spatial phase modulator 21 displaying the CGH, the spatial phase of the control light L2 is controlled (according to the CGH), the in-plane position deviation intersecting the optical axis direction of the control light L2 and the diffusion angle of the control light L2 are corrected and maintained in the initial state.

[0085] To elaborate on this point in more detail. Figure 14 (a) displays the actual CGH generated for correction. The control unit 60 displays this CGH on the spatial phase modulator 21. Thus, as... Figure 14 As shown in (b) to (d), it should be understood that... Figure 11 In contrast, the diffusion angle (brightness, spot size) of the control light L2 is corrected and returned to normal. Figure 10 The initial state. Similarly, from Figure 15 The initial state of (a) is as follows Figure 15 (b) The position of the control light L2 generated in the plane intersecting the optical axis is deviated, such as... Figure 15 As shown in (c), it is corrected and returns to the initial state.

[0086] Furthermore, regarding the uncontrolled light L3, since it is not controlled by the spatial phase in the spatial phase modulator 21, it is therefore... Figure 15 The initial state of (d) is as follows Figure 15 In the case of positional deviation in the XY plane as in (e), even if the CGH is displayed on the spatial phase modulator 21, it will still appear as... Figure 15 Maintaining (f) Figure 15 The state of (e).

[0087] Subsequently, the control unit 60 determines whether to continue the above control (process S6). If the result of the determination in process S6 is that control should not continue, the process ends. On the other hand, if the result of the determination in process S6 is that control should continue, the process returns to process S1 and repeats the process.

[0088] As described above, the control unit 60 performs a correction process for the phase control unit 20 by correcting the spatial phase state of the control light L2 in the phase control unit 20 based on the detection result of the non-control light L3 from the second detection unit 50. More specifically, the control unit 60 performs a first correction process for the phase control unit 20 by correcting the positional deviation of the control light L2 in the plane intersecting the optical axis direction of the control light L2 based on the obtained first deviation amount. In addition, the control unit 60 performs a second correction process for the phase control unit 20 by correcting the diffusion angle of the control light L2 based on the obtained diffusion angle.

[0089] Specifically, here, the phase control unit 20 includes a spatial phase modulator 21, which displays a phase modulation pattern (CGH) for branching the input laser L1 into multiple diffracted beams and emitting them, thereby emitting the 0th order light of the laser L1 as the uncontrolled light L3 and emitting the diffracted beams of other orders of the laser L1 as the control light L2. Based on the detection result of the uncontrolled light L3, the control unit adjusts the phase modulation pattern displayed on the spatial phase modulator 21, thereby correcting the control state of the spatial phase of the control light L2 in the phase control unit 20.

[0090] Furthermore, in the aforementioned processes, the control unit 60 performs feedback control on the phase control unit 20 by correcting changes in the focusing state of the control light L2 from the laser source 10 based on the detection results of the second detector 50. On the other hand, the control unit 70 can perform processing to correct changes in the focusing state of the control light L2 from sources other than the laser source 10, based on the detection results of the first detector 40, in parallel (or individually) with the aforementioned processes. For example, if the control light L2 branches into multiple points as described above, the control unit 70 can perform feedback control on the phase control unit 20 by uniformizing the intensity distribution of each point of the control light L2 or individually controlling the intensity of each point, based on the detection results (image) of the first detector 40. In this case, the CGH generated by the control unit 60 can be superimposed on the CGH controlled by the control unit 70.

[0091] As explained above, in the laser processing apparatus 100, a portion of the laser L1 emitted from the laser source 10 has its spatial phase controlled by the phase control unit 20 and serves as control light L2, which is then used to irradiate the object A via the first optical system 30. On the other hand, another portion of the laser L1 emitted from the laser source 10 serves as uncontrolled light L3, which is focused by the lens 80 onto the imaging surface 50s of the second detector 50. Thus, the uncontrolled light L3, which is not controlled by the phase control unit 20, is detected within the laser L1 emitted from the laser source 10. This uncontrolled light L3 is less susceptible to the influence of the phase control unit 20, maintaining the characteristics of the laser L1 at the point of emission from the laser source 10. Therefore, the control unit 60 controls the phase control unit 20 in a manner that corrects the control state of the spatial phase of the control light L2 in the phase control unit 20 based on the detection result of this uncontrolled light L3, thereby easily correcting changes in the focusing state of the laser (control light L2) caused by the laser source 10.

[0092] As a result, even when the characteristics of the laser L1 emitted from the laser source 10 change due to, for example, years of variation, the focusing state of the laser L1 irradiating the object A can be easily maintained at a specific initial value. Especially when multiple laser processing devices 100 are used in parallel, if this specific initial value is common to all laser processing devices 100, even if the focusing state of the laser L1 emitted from the laser source 10 changes differently for each laser processing device 100, the focusing state of the laser L1 in each laser processing device 100 will be maintained at a common initial value, thus reducing machine error. Consequently, based on the detection results of the first detector 40, a common processing method can be implemented to ensure uniform intensity of each point when the control light L2 is branched into multiple points. Thus, since the laser processing device can reduce machine error, it is effective even when multiple devices are used in parallel.

[0093] Furthermore, in the laser processing apparatus 100, the control unit 60 performs the following processes: a first acquisition process, which, based on the detection result of the second detector 50, acquires the deviation amount, i.e., a first deviation amount, of the position of the non-control light L3 in the plane intersecting the optical axis direction of the non-control light L3; and a first correction process, which controls the phase control unit 20 to correct the position deviation of the control light L2 in the plane intersecting the optical axis direction of the control light L2 based on the first deviation amount. Therefore, based on the information related to the position deviation in the plane intersecting the optical axis direction of the non-control light L3, the position deviation in the plane intersecting the optical axis direction of the control light L2 can be easily corrected.

[0094] Furthermore, in the laser processing apparatus 100, the control unit 60 performs the following processes: a second acquisition process, which acquires the diffusion angle of the non-control light L3 based on the detection result of the second detector 50; and a second correction process, which controls the phase control unit 20 in a manner that corrects the diffusion angle of the control light L2 based on the diffusion angle. Therefore, based on information related to the amount of change in the diffusion angle of the non-control light L3, the change in the diffusion angle of the control light L2 can be easily corrected.

[0095] Furthermore, in the laser processing apparatus 100, the control unit 60 detects the uncontrolled light L3 while driving the second detector 50 along the optical axis of the uncontrolled light L3, thereby obtaining the second deviation amount, which is the amount of deviation of the position where the uncontrolled light L3 is most focused on the imaging surface 50s from its initial position, and obtaining the diffusion angle based on the second deviation amount. Therefore, information related to the change in the diffusion angle of the uncontrolled light L3 can be obtained based on the mechanical drive of the second detector 50.

[0096] Furthermore, in the laser processing apparatus 100, the phase control unit 20 includes a spatial phase modulator 21, which displays a phase modulation pattern for branching the input laser L1 into multiple diffracted beams and emitting them. This allows the 0th order light of the laser L1 to be emitted as uncontrolled light L3, and the diffracted beams of other orders of the laser L1 to be emitted as control light L2. Based on the detection result of the uncontrolled light L3, the control unit 60 adjusts the phase modulation pattern (CGH) displayed on the spatial phase modulator 21, thereby correcting the control state of the spatial phase of the control light L2 in the phase control unit 20. Thus, by including the spatial phase modulator 21 and branching the laser into multiple beams through diffraction, the undiffracted 0th order light is appropriately used as uncontrolled light, and by adjusting the phase modulation pattern (hologram) displayed on the liquid crystal layer, changes in the focusing state of the control light L2 can be easily corrected.

[0097] Furthermore, the laser processing apparatus 100 includes a first detector 40 for detecting the control light L2 emitted from the phase control unit 20. The control unit 70 then generates a phase modulation pattern for adjusting the spatial phase of the control light L2 in the phase control unit 20 based on the detection result of the control light L2 from the first detector 40, and overlays this phase modulation pattern onto a phase modulation pattern adjusted through correction processing, displaying it on the spatial phase modulator 21. Therefore, based on the detection result of the control light L2, the control state of the control light L2 can be adjusted according to changes in the laser light (control light L2) caused by factors other than the laser source 10.

[0098] The above embodiments illustrate one aspect of the present invention. Therefore, the present invention is not limited to the above-described embodiment and can be modified in any way. Next, modified examples will be described.

[0099] Figure 16 This is a block diagram of a modified laser processing apparatus. Figure 17 yes Figure 16 The diagram shows a schematic of a laser processing device. Figure 16 , 17 The laser processing apparatus (laser device) 100A shown differs from the laser processing apparatus 100 of the above embodiment in that the phase control unit 20 further includes a polarization control element 23, and a polarizing element 90 is provided in front of the second detector 50. Furthermore, the control unit 70 is omitted in the laser processing apparatus 100A. Therefore, the function of the control unit 70 is implemented by the control unit 60. This allows for the standardization of the control unit.

[0100] A polarization control element 23 is interposed in the optical path of the laser L1 between the laser source 10 and the spatial phase modulator 21. The polarization control element 23 is, for example, a λ / 2 wavelength plate, which is input to the laser L1 emitted from the laser source 10. Thus, the polarization control element 23 changes the polarization direction of the laser L1 so that the input laser L1 contains both S-polarization and P-polarization components before emitting it.

[0101] From the perspective of improving the utilization efficiency of laser L1 in spatial phase modulator 21, such as Figure 18 As shown in (a), the polarization direction of laser L1 is changed in a manner that only the polarization component sensitive to the liquid crystal layer of spatial phase modulator 21 is changed. On the other hand, here, as Figure 18 As shown in (b), the polarization direction of laser L1 is changed in a manner that includes both P-polarized and S-polarized components. Therefore, in laser L1, one of the P-polarized and S-polarized components (e.g., the P-polarized component) is spatially phase-controlled in the spatial phase modulator 21 and becomes the control light L2. On the other hand, in laser L1, the other of the P-polarized and S-polarized components (e.g., the S-polarized component) is not spatially phase-controlled in the spatial phase modulator 21 and becomes the uncontrolled light L3.

[0102] The polarizer 90 is positioned between the mirror 32 and the second detector 50, intervening in the optical paths of the control light L2 and the uncontrolled light L3. The polarizer 90 allows only one of the P-polarized and S-polarized components (e.g., the S-polarized component) to pass through. Therefore, in the laser processing apparatus 100A, a portion of the control light L2 and the uncontrolled light L3 emitted from the phase control unit 20 passes through the mirror 32 and enters the polarizer 90, but only the uncontrolled light L3 passes through the polarizer 90 and enters the second detector 50. That is, here, the second detector 50 only detects (captures) the uncontrolled light L3.

[0103] Even with the laser processing apparatus 100A configured as described above, like the laser processing apparatus 100, the phase control unit 20 can be controlled by correcting the spatial phase control state of the control light L2 in the phase control unit 20 based on the detection result of the non-control light L3. Therefore, the laser processing apparatus 100A can also perform the same function and effect as the laser processing apparatus 100.

[0104] Specifically, in the laser processing apparatus 100, the phase control unit 20 includes: a polarization control element 23, which changes the polarization direction of the input laser L1 such that it contains both S-polarization and P-polarization components, and then emits it; and a liquid crystal spatial phase modulator 21, which controls the spatial phase of one of the P-polarization and S-polarization components of the laser L1 emitted from the polarization control element 23 and emits it as control light L2, and emits the other of the P-polarization and S-polarization components of the laser L1 as non-control light L3. Therefore, based on the detection result of the non-control light L3, the control unit 60 adjusts the phase modulation pattern displayed on the spatial phase modulator 21, thereby correcting the control state of the spatial phase of the control light L2 in the phase control unit 20. Thus, by appropriately using the polarization component, which has no sensitivity to the liquid crystal layer, as the non-control light L3, and by adjusting the phase modulation pattern (hologram) displayed on the liquid crystal layer, changes in the focusing state of the control light L2 can be easily corrected.

[0105] Furthermore, in the laser processing apparatus 100, the phase control unit 20, which can replace the liquid crystal type spatial phase modulator 21, is equipped with a phase control unit 20A (refer to) that utilizes a diffractive optical element (DOE) 120. Figure 19 ).

[0106] Figure 19 This is a schematic diagram showing the phase control unit of a modified example. For example... Figure 19 As shown, the phase control unit 20A includes a diffractive optical element 120, a lens 121, a lens 122, a movable mirror 123, and a movable mirror 124. The lens 121, lens 122, movable mirror 123, and movable mirror 124 are sequentially arranged in the optical path of the laser L1 incident on the diffractive optical element 120.

[0107] The diffractive optical element 120 is used to diffract the incident laser L1 into multiple diffracted beams and emit them. The diffractive optical element 120 emits the 0th order light of the laser L1 as the uncontrolled light L3, and emits the other orders of diffracted light of the laser L1 as the controlled light L2.

[0108] The movable mirror 123 can rotate, for example, about an axis along one direction of the defined XY plane, namely the X-axis, and the movable mirror 124 can rotate, for example, about an axis along another direction of the defined XY plane, namely the Y-axis. Therefore, when a positional deviation of the non-control light L3 occurs in the XY plane (i.e., when Δx and Δy are taken as the first deviation), the control unit 60 drives the movable mirrors 123 and 124 to make adjustments with Δx and Δy set to 0. As a result, the positional deviation of the control light L2 is corrected.

[0109] Furthermore, lenses 121 and 122, for example, constitute a Galilean telescope. Its magnification is expressed using the focal distance f1 of lens 121 and the focal distance f2 of lens 122 as -(focal distance f2) / (focal distance f1). Additionally, in the initial state, the distance d between lenses 121 and 122 is equal to the sum of the focal distances f1 and f2. Lens 122 is movable along the optical axis. Therefore, when the diffusion angle of the non-control light L3 changes (i.e., when a second deviation is obtained), the control unit 60 can correct the diffusion angle of the control light L2 by changing the position of lens 122 along the optical axis.

[0110] That is, in this modified example, the control unit 60 can also perform a correction process for controlling the phase control unit 20A in a manner that corrects the spatial phase state of the control light L2 in the phase control unit 20A based on the detection result of the uncontrolled light L3 from the second detector 50. More specifically, the control unit 60 can perform the first correction process and the second correction process in the same manner as in the above embodiment.

[0111] Alternatively, in the phase control unit 20A, lenses 121 and 122 constituting the aforementioned Galilean telescope can be replaced with a structure as described above. Figure 20 Lenses 121A and 122A of the Keplerian telescope are shown. In this case, the magnification is expressed as (focal distance f2) / (focal distance f1) using the focal distance f1 of lens 121A and the focal distance f2 of lens 122A. Furthermore, the initial distance d between lenses 121 and 122 is equal to the sum of the focal distances f1 and f2.

[0112] Furthermore, in the above embodiments and modifications, a laser processing apparatus for processing object A was illustrated. However, the present invention can also be applied to laser apparatuses for purposes different from the processing purpose, such as microscopes.

[0113] Industrial availability

[0114] A laser device that can easily correct changes in the focusing state can be provided.

[0115] Explanation of symbols

[0116] 100, 100A… Laser processing apparatus (laser device), 10… Laser source, 20… Phase control unit, 21… Spatial phase modulator (liquid crystal type spatial phase modulator), 23… Polarizing control element, 30… First optical system, 40… First detector (other detectors), 50… Second detector (detector), 50s… Imaging surface (detection surface), 60, 70… Control unit, 80… Lens (second optical system).

Claims

1. A laser device, wherein, have: A laser source that emits laser light; A phase control unit is used to input the laser emitted from the laser source, control the spatial phase of a portion of the laser light and emit it as control light, and emit another portion of the laser light as non-control light. The first optical system is used to illuminate the object with the control light emitted from the phase control unit; A detector for detecting the uncontrolled light emitted from the phase control unit; The second optical system is used to focus the uncontrolled light emitted from the phase control unit toward the detection surface of the detector; The control unit performs a correction process of the phase control unit to control the spatial phase state of the control light in the phase control unit based on the detection result of the uncontrolled light from the detector. and Other detectors are used to detect the control light emitted from the phase control unit. The control unit performs: The first acquisition process, based on the detection result, acquires a first deviation amount as the deviation amount of the position of the uncontrolled light in a plane intersecting the optical axis direction of the uncontrolled light; and The first correction process, as the correction process, controls the phase control unit in a manner that corrects the positional deviation of the control light in the plane intersecting the optical axis direction of the control light, based on the first deviation amount.

2. A laser device, wherein, have: A laser source that emits laser light; A phase control unit is used to input the laser emitted from the laser source, control the spatial phase of a portion of the laser light and emit it as control light, and emit another portion of the laser light as non-control light. The first optical system is used to illuminate the object with the control light emitted from the phase control unit; A detector for detecting the uncontrolled light emitted from the phase control unit; The second optical system is used to focus the uncontrolled light emitted from the phase control unit toward the detection surface of the detector; The control unit performs a correction process of the phase control unit to control the spatial phase state of the control light in the phase control unit based on the detection result of the uncontrolled light from the detector. and Other detectors are used to detect the control light emitted from the phase control unit. The control unit performs: The second processing step involves obtaining the diffusion angle of the uncontrolled light based on the detection results; and The second correction process, as the correction process, controls the phase control unit by correcting the diffusion angle of the control light based on the diffusion angle.

3. The laser device as described in claim 2, wherein, In the second acquisition process, the control unit detects the uncontrolled light while driving the detector along the optical axis of the uncontrolled light, and obtains a second deviation amount, which is the deviation of the position where the uncontrolled light is most focused on the detection surface from the initial position, and obtains the diffusion angle based on the second deviation amount.

4. A laser device, wherein, have: A laser source that emits laser light; A phase control unit is used to input the laser emitted from the laser source, control the spatial phase of a portion of the laser light and emit it as control light, and emit another portion of the laser light as non-control light. The first optical system is used to illuminate the object with the control light emitted from the phase control unit; A detector for detecting the uncontrolled light emitted from the phase control unit; The second optical system is used to focus the uncontrolled light emitted from the phase control unit toward the detection surface of the detector; The control unit performs a correction process of the phase control unit to control the spatial phase state of the control light in the phase control unit based on the detection result of the uncontrolled light from the detector. and Other detectors are used to detect the control light emitted from the phase control unit. The phase control unit includes: A polarization control element that changes the polarization direction of the input laser light and emits it in such a way that the input laser light contains both S-polarization and P-polarization components; and A liquid crystal spatial phase modulator controls the spatial phase of one of the S-polarized and P-polarized components of the laser emitted from the polarization control element and emits it as the control light, while emitting the other of the S-polarized and P-polarized components of the laser as the uncontrolled light. In the correction process, the control unit adjusts the phase modulation pattern displayed on the liquid crystal spatial phase modulator based on the detection result of the non-control light, thereby correcting the control state of the spatial phase of the control light in the phase control unit.

5. A laser device, wherein, have: A laser source that emits laser light; A phase control unit is used to input the laser emitted from the laser source, control the spatial phase of a portion of the laser light and emit it as control light, and emit another portion of the laser light as non-control light. The first optical system is used to illuminate the object with the control light emitted from the phase control unit; A detector for detecting the uncontrolled light emitted from the phase control unit; The second optical system is used to focus the uncontrolled light emitted from the phase control unit toward the detection surface of the detector; The control unit performs a correction process of the phase control unit to control the spatial phase state of the control light in the phase control unit based on the detection result of the uncontrolled light from the detector. and Other detectors are used to detect the control light emitted from the phase control unit. The phase control unit includes a liquid crystal spatial phase modulator, which displays a phase modulation pattern for branching the input laser into multiple diffracted beams and emitting them, thereby emitting the 0th order light of the laser as the uncontrolled light and emitting the diffracted light of other orders of the laser as the control light. In the correction process, the control unit adjusts the phase modulation pattern displayed on the liquid crystal spatial phase modulator based on the detection result of the non-control light, thereby correcting the control state of the spatial phase of the control light in the phase control unit. The control unit generates a phase modulation pattern for adjusting the spatial phase of the control light in the phase control unit based on the detection results of the control light from the other detectors, and overlays the phase modulation pattern on the phase modulation pattern adjusted by the correction process and displays it on the liquid crystal spatial phase modulator.

Images