Patent Description:
Patent Literature <NUM> describes a laser processing device. This laser processing device includes a converging lens, a variable focus lens, a convergence position measuring unit, a convergence position control unit, an optical system, and a light source. The converging lens causes laser light supplied from the light source to converge onto a surface to be treated of an object. The laser light supplied from the light source passes through an optical fiber, is optically shaped by the optical system, and converges through the converging lens. The variable focus lens is disposed on an optical path of the converging lens. The variable focus lens can change a focal length by voltage application. The convergence position measuring unit measures a convergence position of the converging lens using light extracted by a semi-reflection mirror.

<CIT> relates to a laser beam irradiation apparatus for irradiating an object including a reflective surface with a laser beam. <CIT> and <CIT> relate to a light irradiation apparatus for irradiating light onto an object to be irradiated. <CIT> relates to a light source unit that outputs light, an irradiation optical system that irradiates an object with light output from the light source unit, and a detection optical system that guides light generated when the object is irradiated by the irradiation optical system. <CIT> relates to a laser processing device. <CIT> relates to an image acquisition device. <CIT> relates to a laser machining system. <CIT> relates to a laser for processing a workpiece by phase-modulating laser light emitted from a laser light source by a spatial phase modulation element. <CIT> relates to a control apparatus for a spatial light modulator.

In the laser processing device described in Patent Literature <NUM> described above, the convergence position control unit controls a focal position of the variable focus lens such that a difference between a convergence position measured by the convergence position measuring unit and a set specific convergence position is within a set allowable range. As a result, an initial focal position is maintained.

Incidentally, for example, in order to improve a processing speed, it is conceivable to adopt a phase controller such as a liquid crystal type spatial phase modulator (for example, LCOS-SLM) in the laser processing device described above and to branch the laser light into a plurality of rays. In this case, in a case where the convergence position changes with an operation of the laser processing device, it is conceivable to perform feedback control of the phase controller in order to correct the change. In this case, if it is possible to detect that the change in the convergence position is caused by the light source, the control of the phase controller becomes simple. However, in the laser processing device described above, since the semi-reflection mirror guides all the laser light to the convergence position measuring unit, it is difficult to detect whether the change in the convergence position is caused by the light source or is caused by another optical system such as the phase controller.

Accordingly, an object of the present disclosure is to provide a laser device capable of easily correcting a change in a convergence state.

As a result of intensive research to solve the above problem, the inventors of the present invention have obtained the following findings. That is, in a phase controller such as a spatial phase modulator, for example, a portion of incident laser light is subjected to phase control, is emitted as control light, and is used for irradiating an object, and another portion of the incident laser light is not subjected to the phase control and is emitted as non-control light. This non-control light tends to be treated as loss and noise because the desired phase control is not performed. However, on the other hand, since the non-control light is less likely to be affected by the phase controller, the non-control light maintains the characteristics of the laser light at a time point that it is emitted from a light source. Therefore, by detecting this non-control light, it is possible to detect a change in a convergence state caused by the light source, and it is possible to easily correct the change through feedback control of the phase controller. The present disclosure is the result of further studies by the inventors of the present invention on the basis of such findings.

That is, according to the present invention, there is provided a laser device defined in claim <NUM>.

In this laser device, a portion of the laser light emitted from the laser light source is controlled in the spatial phase by the phase control unit to become the control light and is used for the first optical system to irradiate the object. On the other hand, another portion of the laser light emitted from the laser light source converges toward the detection surface of the detector as the non-control light through the second optical system. As a result, the non-control light not subjected to the control in the phase control unit of the laser light emitted from the laser light source is detected. As shown in the above findings, this non-control light is less likely to be affected by the phase control unit and maintains the characteristics of the laser light when emitted from the light source. Therefore, the control unit can easily correct the change in the convergence state of the laser light (the control light) caused by the light source by controlling the phase control unit to correct the control state for the spatial phase of the control light in the phase control unit on the basis of the detection result for this non-control light.

As a result, even in a case where the characteristics of the laser light emitted from the laser light source change due to aging, for example, the convergence state of the laser light with which the object is irradiated can be easily maintained at a specific initial value. Particularly, if the specific initial value is common among the plurality of laser devices in a case where a plurality of laser devices are used in parallel, the convergence state of the laser light in each laser device is maintained at the common initial value even in a case where the change in the convergence state of the laser light emitted from the laser light source varies for each laser device, and thus a machine difference is reduced. In this way, since this laser device can reduce the machine difference, it is also effective in a case where the plurality of laser processing devices are used in parallel.

In the laser device according to the present disclosure, the control unit may execute a first acquisition process of acquiring a first deviation amount, which is a deviation amount of a position of the non-control light within a plane intersecting with an optical axis direction of the non-control light, on the basis of the detection result, and a first correction process, as the correction process, of controlling the phase control unit to correct positional deviation of the control light within a plane intersecting with an optical axis direction of the control light on the basis of the first deviation amount. In this case, it is possible to easily correct the positional deviation of the control light within the plane intersecting with the optical axis direction on the basis of the information on the positional deviation of the non-control light within the plane intersecting with the optical axis direction.

In the laser device according to the present disclosure, the control unit may execute a second acquisition process of acquiring a spread angle of the non-control light on the basis of the detection result, and a second correction process, as the correction process, of controlling the phase control unit to correct a spread angle of the control light on the basis of the acquired spread angle. In this case, it is possible to easily correct the change in the spread angle of the control light on the basis of the information on the change amount in the spread angle of the non-control light.

In the laser device according to the present disclosure, in the second acquisition process, the control unit may drive the detector in the optical axis direction of the non-control light while detecting the non-control light, acquire a second deviation amount which is a deviation amount of a position at which the non-control light most converges on the detection surface, from an initial position, and acquire the spread angle on the basis of the second deviation amount. In this case, according to the mechanical driving of the detector, it is possible to acquire the information on the change in the spread angle of the non-control light.

In the laser device according to the present disclosure, the phase control unit may include a polarization control element configured to change a polarization direction of the laser light such that the received laser light includes an S-polarized component and a P-polarized component and to emit the changed laser light, and a liquid crystal type spatial phase modulator configured to control a spatial phase of the P-polarized component of the laser light emitted from the polarization control element, to emit the controlled P-polarized component as the control light, and to emit the S-polarized component of the laser light as the non-control light, and wherein, in the correction process, the control unit may adjust a phase modulation pattern displayed on the liquid crystal type spatial phase modulator on the basis of a detection result for the non-control light to correct a control state for a spatial phase of the control light in the phase control unit. In this way, in a case where the phase control unit includes the liquid crystal type spatial phase modulator, if the polarization direction is adjusted such that the laser light contains both the P-polarized light and the S-polarized light, while the S-polarized component that is not sensitive to the liquid crystal layer is suitably used as the non-control light, the change in the convergence state of the control light can be easily corrected through the adjustment of the phase modulation pattern (the hologram) displayed on the liquid crystal layer.

In the laser device according to the present disclosure, the phase control unit may include a liquid crystal type spatial phase modulator that displays a phase modulation pattern for diffracting the received laser light to branch the laser light into a plurality of rays of diffraction light and to emit the branched rays of diffraction light, emits Oth-order light of the laser light as the non-control light, and emits another order diffraction light of the laser light as the control light, and in the correction process, the control unit may adjust the phase modulation pattern displayed on the liquid crystal type spatial phase modulator on the basis of a detection result for the non-control light to correct a control state for a spatial phase of the control light in the phase control unit. In this way, in a case where the liquid crystal type spatial phase modulator is included and the laser light is branched into a plurality of rays by diffraction, while the Oth-order light that is not diffracted is suitably used as the non-control light, the change in the convergence state of the control light can be easily corrected through the adjustment of the phase modulation pattern (the hologram) displayed on the liquid crystal layer.

The laser device according to the present disclosure may further include: another detector configured to detect the control light emitted from the phase control unit, wherein the control unit may generate a phase modulation pattern for adjusting a control state for a spatial phase of the control light in the phase control unit on the basis of a detection result of the control light from the another detector and cause the liquid crystal type spatial phase modulator to display the phase modulation pattern superimposed on the phase modulation pattern adjusted by the correction process. In this case, the control state of the control light can be adjusted in accordance with the change in the laser light (the control light) caused by something other than the light source on the basis of the detection result of the control light.

According to the present disclosure, it is possible to provide a laser device capable of easily correcting a change in a convergence state.

Hereinafter, an embodiment will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are denoted with the same reference signs, and repetitive description may be omitted. <FIG> is a block diagram of a laser processing device according to an embodiment. <FIG> is a schematic view of the laser processing device shown in <FIG>. As an example, the laser processing device (a laser device) <NUM> shown in <FIG> and <FIG> performs drilling, cutting, fine processing of a semiconductor, and the like of an object A by irradiating the object A with laser light.

The laser processing device <NUM> includes a laser light source <NUM>, a phase control unit <NUM>, a first optical system <NUM>, a first detector <NUM>, a second detector <NUM>, and a control unit <NUM>. The laser light source <NUM> emits laser light L1. The phase control unit <NUM> includes a spatial phase modulator (a liquid crystal type spatial phase modulator) <NUM> and a mirror <NUM> that guides the laser light L1 to the spatial phase modulator <NUM>. The spatial phase modulator <NUM> has a liquid crystal layer, displays an arbitrary phase modulation pattern (a hologram, a computer generated hologram (CGH)) on the liquid crystal layer under control of the control unit <NUM>, and controls a spatial phase of the laser light L1 according to the phase modulation pattern.

A portion of the laser light L1 incident on the spatial phase modulator <NUM> is emitted from the spatial phase modulator <NUM> with its spatial phase being controlled, while another portion of the laser light L1 incident on the spatial phase modulator <NUM> is emitted from the spatial phase modulator <NUM> without its spatial phase being controlled. That is, the phase control unit <NUM> receives the laser light L1 emitted from the laser light source <NUM>, controls the spatial phase of the portion of the laser light L1, emits the portion of the light as control light L2, and emits the other portion of the laser light L1 as non-control light L3.

A first optical system <NUM> guides the control light L2 emitted from the phase control unit <NUM> and irradiates the object A with the control light L2. The first optical system <NUM> includes mirrors <NUM>, <NUM>, and <NUM> that guide the control light L2 emitted from the spatial phase modulator <NUM> toward the object A. The control light L2 and the non-control light L3 are reflected by the mirrors <NUM>, <NUM>, and <NUM> in order, and the object A is irradiated with the reflected light. Further, the first optical system <NUM> includes lenses <NUM>, <NUM>, and <NUM> disposed in order on an optical path of the control light L2 and the non-control light L3 which is formed by the mirrors <NUM>, <NUM>, and <NUM>. The lens <NUM> and the lens <NUM> form an image of the control light L2 of the spatial phase modulator <NUM> on the lens <NUM>. The lens <NUM> is a converging lens that faces the object A to cause the control light L2 to converge toward the object A.

The first detector (another detector) <NUM> is, for example, a camera for capturing an image of the control light L2 and can be used for detecting a change in the characteristics of the control light L2 under control of a control unit <NUM>. The detection result of the first detector <NUM> can be used for feedback control of the control light L2 by the phase control unit <NUM>, for example. Details of such feedback control will be described later. In addition to the control light L2, the non-control light L3 may also be incident on the first detector <NUM>. Therefore, the first detector <NUM> can also capture an image of the non-control light L3. For example, the first detector <NUM> is disposed on an extension line of the optical path of the control light L2 and the non-control light L3 directed from the mirror <NUM> to the mirror <NUM> and captures an image of a portion of the control light L2 (and the non-control light L3) which is transmitted through the mirror <NUM> and of which an image is formed on an image capturing surface <NUM>. An image corresponding to a processing surface of the object A is formed on the image capturing surface <NUM> of the first detector <NUM>.

The second detector (a detector) <NUM> is, for example, a camera for capturing an image of the non-control light L3 and can be used for detecting a change in the characteristics of the non-control light L3 under control of the control unit <NUM>. The detection result of the second detector <NUM> can be used for feedback control of the non-control light L3 by the phase control unit <NUM>, for example. Details of such feedback control will be described later. In addition to the non-control light L3, the control light L2 may also be incident on the second detector <NUM>. Therefore, the second detector <NUM> can also capture an image of the control light L2. Here, the second detector <NUM> is disposed on an extension line of the optical path of the non-control light L3 (and the control light L2) directed from the mirror <NUM> to the mirror <NUM> and captures an image of a portion of the non-control light L3 (and the control light L2) which is transmitted through the mirror <NUM> and of which an image is formed on an image capturing surface <NUM> (a detection surface). The lens <NUM> is also a second optical system used for causing the non-control light L3 (and the control light L2) to converge toward the image capturing surface <NUM>.

<FIG> is a diagram showing the image capturing surface of the second detector shown in <FIG> and <FIG>. Here, as an example, by a phase modulation pattern including a diffraction grating pattern being displayed on the spatial phase modulator <NUM>, the laser light L1 is branched into a plurality of rays of diffraction light, and a plurality of beam spots are formed on the image capturing surface <NUM>. In the example of <FIG>, a beam spot of the non-control light L3, which is Oth-order light, is formed in the center, and beam spots of the control light L2, which is 1st-order light, are formed around the center, for example. In the example of <FIG>, the control light L2 and the non-control light L3 converge on the image capturing surface <NUM> by a distance Z between the lens <NUM> and the image capturing surface <NUM> being set to a focal length fm of the lens <NUM>.

On the other hand, when a pattern corresponding to a predetermined Fresnel lens is superimposed on the phase modulation pattern of the spatial phase modulator <NUM> and the second detector <NUM> (the image capturing surface <NUM>) is moved in an optical axis direction by position shift from the focal length fm due to addition of a focal length fFL of the Fresnel lens, as shown in <FIG>, the control light L2 subjected to the control of the spatial phase of the spatial phase modulator <NUM> converges on the image capturing surface <NUM>, and a convergence position of the non-control light L3 not subjected to the control of the spatial phase modulator <NUM> is deviated from the image capturing surface <NUM> by the focal length fFL to expand the beam spot. Meanwhile, as shown in <FIG>, when the image capturing surface <NUM> is returned to a position shown in <FIG>, a convergence position of the control light L2 is deviated from the image capturing surface <NUM> by the focal length fFL of the Fresnel lens to expand the beam spots, and the non-control light L3 converges on the image capturing surface <NUM> as before.

A position of the image capturing surface <NUM> in the optical axis direction where the non-control light L3 converges (a distance Z0 between the lens <NUM> and the image capturing surface <NUM>) can be detected, for example, as follows. That is, as shown in a graph of <FIG>, the distance Z0 can be acquired as, for example, a value at which an intensity of the non-control light L3 is the maximum value I0, or a value at which a spot size of the non-control light L3 on the image capturing surface <NUM> is the minimum value WO by capturing an image of the non-control light L3 while moving the image capturing surface <NUM> of the second detector <NUM> in the optical axis direction and acquiring the detection result. Each process of the control and the light detection of the phase control unit <NUM> and the second detector <NUM> can be implemented by the control unit <NUM>. Similar to this, each process of the control and the light detection for the control light L2 can be implemented by the control unit <NUM>. The control unit <NUM> and the control unit <NUM> may perform different kinds of control on the first detector <NUM> and the second detector <NUM>. That is, the control unit <NUM> may implement each process of the control and the light detection for the control light L2 different from that for the non-control light L3.

That is, the control unit <NUM> can control at least the phase control unit <NUM> and the second detector <NUM>. Further, the control unit <NUM> can control at least the phase control unit <NUM> and the first detector <NUM>. The control unit <NUM> executes a process for controlling the phase control unit <NUM> to correct a control state for a spatial phase of the control light L2 in the phase control unit <NUM> on the basis of a detection result for the non-control light L3 from the second detector <NUM>. Further, the control unit <NUM> executes a process for controlling the phase control unit <NUM> to correct a control state for a spatial phase of the control light L2 in the phase control unit <NUM> on the basis of a detection result for the control light L2 from the first detector <NUM>. These processes will be described in detail later. Each of the control units <NUM> and <NUM> has a processing part, a storage part, and an input reception part (not shown). The processing part is configured as a computer device including a processor, a memory, a storage, a communication device, and the like. In the processing part, the processor executes software (a program) read from the memory or the like and controls reading and writing of data in the memory and the storage, and communication of a communication device. The storage part is, for example, a hard disk or the like, and stores various types of data. The input reception part is an interface unit that displays various pieces of information and receives input of various pieces of information from the user.

Subsequently, the details of an operation of the control unit <NUM> will be described by describing a correction method for the laser light implemented by the laser processing device <NUM>. This method is implemented by the control unit <NUM> executing each process. <FIG> is a flowchart showing the correction method for the laser light. The control unit <NUM> holds information indicating an initial state of the laser processing device <NUM> in advance. The information about the initial state held by the control unit <NUM> includes, for example, initial values of a position (coordinates), a spot size (a beam area), luminance, and the like of the non-control light L3 on the image capturing surface <NUM>, and initial values of a position (coordinates), a spot size (a beam area), a luminance, and the like of the control light L2 on the image capturing surface <NUM>.

Here, first, the control unit <NUM> measures displacement from an initial position (step S1). More specifically, the control unit <NUM> executes a first acquisition process of acquiring a first deviation amount which is a deviation amount of a current position of the non-control light L3 from the initial position within a plane intersecting with an optical axis of the non-control light L3 (here, the image capturing surface <NUM>, and hereinafter it may be referred to as "an XY plane") by capturing an image of the non-control light L3 using the second detector <NUM>. <FIG> shows a state where the beam spot of the non-control light L3 is at the initial position (x, y) in the XY plane, and <FIG> shows a state were the beam spot of the non-control light L3 is at a position (x+Δx, y+Δy) displaced from the initial position (x, y) in the XY plane. That is, here, each of Δx and Δy is acquired as the first deviation amount. As an example, Δx = +<NUM> pixels, and Δy = -<NUM> pixels. Such deviation may occur, for example, due to aging.

<FIG> is an image showing the image capturing surface <NUM> of the first detector <NUM>. <FIG> shows a state where the beam spot of the control light L2 is at the initial position. As shown in <FIG>, if the non-control light L3 is deviated from the initial position on the XY plane, the control light L2 is also deviated within the plane intersecting with the optical axis. For example, in Δu and Δv, each of which is the deviation amount on the image capturing surface <NUM>, Δu = + <NUM> pixels, and Δv = -<NUM> pixels. As shown in <FIG> and <FIG>, the control light L2 subjected to the control of the phase control unit <NUM> is deviated, and the non-control light L3 not subjected to the control of the phase control unit <NUM> is also deviated. Therefore, it is understood that the deviation includes at least that caused by the laser light source <NUM> which is a front stage side of the phase control unit <NUM>.

In this step S1, the control unit <NUM> further executes a second acquisition process of acquiring displacement of a spread angle of the non-control light L3 from the initial position by capturing an image of the non-control light L3 using the second detector <NUM>. <FIG> is an image showing a case where the beam spot of the non-control light L3 on the XY plane is in an initial state. <FIG> is an enlarged view of <FIG>. On the other hand, <FIG> is an image showing a state where the beam spot of the non-control light L3 has changed from the initial state in the XY plane. <FIG> is an enlarged view of <FIG>. As shown in <FIG> and <FIG>, here, the spread angle of the non-control light L3 changes within the XY plane. In addition, in <FIG> and <FIG>, dots drawn by software for detecting the beam spot are shown on an outer peripheral portion of the beam spot.

The control unit <NUM> acquires a change amount ΔS of the spot size of the non-control light L3 on the XY plane from an initial value S and/or a change amount ΔI of the intensity of the non-control light L3 on the XY plane from an initial value I on the basis of the detection result (the image) of the second detector <NUM>. These change amounts ΔS and ΔI serve as indices indicating the spread angle of the non-control light L3.

<FIG> is an image showing the image capturing surface <NUM> of the first detector <NUM>. <FIG> is an image showing a case where the beam spot of the control light L2 is in an initial state. <FIG> is an enlarged view of <FIG>. On the other hand, <FIG> is an image showing a state where the beam spot of the control light L2 has changed from the initial state. <FIG> is an enlarged view of <FIG>. As shown in <FIG> and <FIG>, here, the spread angle of the control light L2 also changes.

As shown in <FIG>, if the spread angle of the non-control light L3 changes, the spread angle of the control light L2 also changes. While the spread angle of the control light L2 subjected to the control of the phase control unit <NUM> changes, the spread angle of the non-control light L3 not subjected to the control of the phase control unit <NUM> also changes. Therefore, it is understood that the change includes at least that caused by the laser light source <NUM>.

In the subsequent step, the control unit <NUM> transforms the coordinates (x+Δx, y+Δy) on the XY plane (the image capturing surface <NUM>) of the non-control light L3 including Δx and Δy as the first deviation amount into the coordinates on a hologram displayed by the spatial phase modulator <NUM> (hereinafter it may be referred to as "coordinates on a UV plane") (step S2). <FIG> is a diagram for explaining an example of coordinate transformation. The transformation of a scale s between the coordinates on the XY plane and the coordinates on the UV plane is shown by the following equation (<NUM>), and the transformation of an angle θ is shown by the following equation (<NUM>). Therefore, the coordinate transformation between the coordinates on the XY plane and the coordinates on the UV plane is given by the following equation (<NUM>). As an example, when the coordinates of the non-control light L3 on the XY plane are (x1, y1), the coordinates of the non-control light L3 on the UV plane are calculated as (u1, <NUM>). <NUM>] <MAT> [Math. <NUM>] <MAT> [Math. <NUM>] <MAT>.

In the subsequent step, the control unit <NUM> determines whether or not the state change of the non-control light L3 is within an allowable range (step S3). More specifically, the control unit <NUM> determines whether or not the change amount ΔS of the spot size of the non-control light L3 on the XY plane from the initial value S and/or the change amount ΔI of the intensity of the non-control light L3 on the XY plane from the initial value I, which are acquired in step S1, is within the allowable range. That is, here, as an example, it is determined whether or not the spread angle is within the allowable range.

In a case where the state change of the non-control light L3 is not within the allowable range as a result of the determination in step S3 (step S3: No), the control unit <NUM> acquires the spread angle of the non-control light L3 on the XY plane (step S4, the second acquisition process). More specifically, the control unit <NUM> first drives the second detector <NUM> in the optical axis direction of the non-control light L3 while detecting the non-control light L3 using the second detector <NUM> and acquires a second deviation amount which is a deviation amount of a position at which the non-control light L3 most converges on the image capturing surface <NUM>, from the initial position.

<FIG> is a graph of a case where the second deviation amount is acquired on the basis of various indices. In <FIG>, a horizontal axis indicates a relative position (that is, the second deviation amount) of the second detector <NUM> (the camera) in the optical axis direction from the initial position. <FIG> uses the peak luminance of the non-control light L3 as an index, and <FIG> uses the luminance density of the non-control light L3 as an index. In these cases, the maximum value of each index is obtained by moving the second detector <NUM> in the optical axis direction, and thus the relative position at which the maximum value is obtained becomes the second deviation amount.

On the other hand, <FIG> uses the spot size (the beam area) as an index. In this case, the minimum value can be obtained by moving the second detector <NUM> in the optical axis direction. Then, the relative position at which the minimum value is obtained becomes the second deviation amount. Here, in either case, the second deviation amount of <NUM> is acquired. The second deviation amount is a shift amount of the focal position of the non-control light L3 in the optical axis direction.

Furthermore, here, the control unit <NUM> calculates the spread angle of the non-control light L3 on the basis of the acquired second deviation amount. The spread angle is calculated as the focal length fFL of the Fresnel lens corresponding to the second deviation amount. The focal length fFL corresponding to the second deviation amount is obtained by the following equation. Specifically, the following equation (<NUM>) relates to a focal length f0 of the composite lens of the Fresnel lens and the lens <NUM> realized by the CGH displayed on the spatial phase modulator <NUM>, and the following equations (<NUM>) and (<NUM>) are obtained by transforming the following equation (<NUM>) into an equation for the focal length fFL of the Fresnel lens. d in the following equation is a distance between the lens <NUM> and the Fresnel lens. <NUM>] <MAT> [Math. <NUM>] <MAT> [Math. <NUM>] <MAT>.

On the other hand, when the second deviation amount (the shift amount of the focal position) acquired as described above is Δd, f0 = fm + Δd. Therefore, when this is introduced in the above equation (<NUM>), the focal length fFL of the corresponding Fresnel lens is represented as the following equation (<NUM>). In addition, when this equation is further transformed, the focal length fFL is acquired as the following equation (<NUM>). As an example, when Δd is <NUM> as above, the focal length fFL of the corresponding Fresnel lens is <NUM>. <NUM>] <MAT> [Math. <NUM>] <MAT>.

In a case where the state change of the non-control light L3 is within the allowable range as a result of the determination in step S3 (step S3: YES), the control unit <NUM> assumes that the spread angle of the non-control light L3 is <NUM>, that is, assumes that the focal length fFL of the Fresnel lens is infinite (step S5), and the process proceeds to subsequent step S6. The focal length fFL of the Fresnel lens being infinite means that a component of the Fresnel lens is not added when a CGH for correction is generated. Further, in the above example, a case where the spread angle is positive (a case where a change in a divergence direction occurs) is shown, but a case where the spread angle is negative (a case where a change in a convergence direction occurs) is also possible.

In the subsequent step, the control unit <NUM> generates a CGH for correcting the state change as described above (step S6). More specifically, the control unit <NUM> generates a CGH on which a pattern including Δx and Δy each of which is the first deviation amount acquired as described above and parameters (-Δu, -Δv, -fFL) for counteracting the focal length fFL of the Fresnel lens as the spread angle corresponding to the second deviation amount is superimposed. The control unit <NUM> causes the spatial phase modulator <NUM> to display the generated CGH. As a result, the spatial phase of the control light L2 is controlled by the spatial phase modulator <NUM> on which the CGH is displayed (according to the CGH), and the positional deviation of the control light L2 within the plane intersecting with the optical axis direction and the spread angle of the control light L2 are corrected, and thus it is maintained in the initial state.

This point will be described more specifically. <FIG> shows the CGH for correction actually generated. The control unit <NUM> causes the spatial phase modulator <NUM> to display this CGH. As a result, as shown in <FIG>, the spread angle (the luminance, the spot size) of the control light L2 is corrected as compared with <FIG>, and it is understood that it returns to the initial state of <FIG>. Similarly, the positional deviation of the control light L2 which occurs within the plane intersecting with the optical axis direction as shown in <FIG> from the initial state of <FIG> is corrected as shown in <FIG>, and thus it returns to the initial state.

Since the non-control light L3 is not subjected to the control for the spatial phase of the spatial phase modulator <NUM>, in a case where the positional deviation occurs within the XY plane as shown in <FIG> from the initial state of <FIG>, even if the CGH is displayed on the spatial phase modulator <NUM>, the state of <FIG> is maintained as shown in <FIG>.

After that, the control unit <NUM> determines whether or not to continue the above control (step S6). In a case where the result of determination in step S6 indicates that the control should not be continued, the process ends. On the other hand, in a case where the result of determination in step S6 indicates that the control should be continued, the process returns to step S1 to repeat the process.

As described above, the control unit <NUM> executes the correction process of controlling the phase control unit <NUM> to correct the control state for the spatial phase of the control light L2 in the phase control unit <NUM> on the basis of the detection result for the non-control light L3 from the second detector <NUM>. More specifically, the control unit <NUM> executes a first correction process of controlling the phase control unit <NUM> to correct the positional deviation of the control light L2 within the plane intersecting with the optical axis direction of the control light L2 on the basis of the acquired first deviation amount. Further, the control unit <NUM> executes a second correction process of controlling the phase control unit <NUM> to correct the spread angle of the control light L2 on the basis of the acquired spread angle.

In particular, here, the phase control unit <NUM> includes the spatial phase modulator <NUM> that displays the phase modulation pattern (CGH) for diffracting the received laser light L1 to branch the laser light L1 into a plurality of rays of diffraction light and to emit the branched rays of diffraction light, emits Oth-order light of the laser light L1 as the non-control light L3, and emits another order diffraction light of the laser light L1 as the control light L2. Then, the control unit adjusts the phase modulation pattern displayed on the spatial phase modulator <NUM> on the basis of the detection result for the non-control light L3 to correct the control state for the spatial phase of the control light L2 in the phase control unit <NUM>.

In each of the steps described above, the control unit <NUM> feedback-controls the phase control unit <NUM> to correct a change in a convergence state of the control light L2 derived from the laser light source <NUM> on the basis of the detection result of the second detector <NUM>. On the other hand, in parallel with (or separately from) each of the above steps, the control unit <NUM> can execute the process of correcting a change in a convergence state of the control light L2 derived from something other than the laser light source <NUM> on the basis of the detection result of the first detector <NUM>. For example, in a case where the control light L2 is branched into multiple points as described above, the control unit <NUM> can feedback-control the phase control unit <NUM> to make the intensity distribution of the points of the control light L2 uniform or to individually control the intensities of the points thereof on the basis of the detection result (the captured image) of the first detector <NUM>. In this case, the CGH for the control of the control unit <NUM> only has to be superimposed on the CGH generated by the control unit <NUM> or the like.

As described above, in the laser processing device <NUM>, a portion of the laser light L1 emitted from the laser light source <NUM> is controlled in the spatial phase by the phase control unit <NUM> to become the control light L2 and is used for the first optical system <NUM> to irradiate the object A. On the other hand, another portion of the laser light L1 emitted from the laser light source <NUM> converges toward the image capturing surface <NUM> of the second detector <NUM> as the non-control light L3 through the lens <NUM>. As a result, the non-control light L3 not subjected to the control in the phase control unit <NUM> of the laser light L1 emitted from the laser light source <NUM> is detected. This non-control light L3 is less likely to be affected by the phase control unit <NUM> and maintains the characteristics of the laser light L1 when emitted from the laser light source <NUM>. Therefore, the control unit <NUM> can easily correct the change in the convergence state of the laser light (the control light L2) caused by the laser light source <NUM> by controlling the phase control unit <NUM> to correct the control state for the spatial phase of the control light L2 in the phase control unit <NUM> on the basis of the detection result for this non-control light L3.

As a result, even in a case where the characteristics of the laser light L1 emitted from the laser light source <NUM> change due to aging, for example, the convergence state of the laser light L1 with which the object A is irradiated can be easily maintained at a specific initial value. Particularly, if the specific initial value is common among the plurality of laser processing devices <NUM> in a case where a plurality of laser processing devices <NUM> are used in parallel, the convergence state of the laser light L1 in each laser processing device <NUM> is maintained at the common initial value even in a case where the change in the convergence state of the laser light L1 emitted from the laser light source <NUM> varies for each laser processing device <NUM>, and thus a machine difference is reduced. As a result, from the detection result of the first detector <NUM>, when the control light L2 is branched into multiple points, it is possible to make the individual intensities uniform by a common processing method. In this way, since this laser processing device can reduce the machine difference, it is also effective in a case where the plurality of laser processing devices are used in parallel.

Further, in the laser processing device <NUM>, the control unit <NUM> executes the first acquisition process of acquiring the first deviation amount which is the deviation amount of the position of the non-control light L3 within the plane intersecting with the optical axis direction of the non-control light L3 on the basis of the detection result of the second detector <NUM> and executes the first correction process of controlling the phase control unit <NUM> to correct the positional deviation of the control light L2 within the plane intersecting with the optical axis direction of the control light L2 on the basis of the first deviation amount. Therefore, it is possible to easily correct the positional deviation of the control light L2 within the plane intersecting with the optical axis direction on the basis of the information on the positional deviation of the non-control light L3 within the plane intersecting with the optical axis direction.

Further, in the laser processing device <NUM>, the control unit <NUM> executes the second acquisition process of acquiring the spread angle of the non-control light L3 on the basis of the detection result of the second detector <NUM> and executes the second correction process of controlling the phase control unit <NUM> to correct the spread angle of the control light L2 on the basis of the spread angle of the non-control light L3. Therefore, it is possible to easily correct the change in the spread angle of the control light L2 on the basis of the information on the change amount in the spread angle of the non-control light L3.

Further, in the laser processing device <NUM>, the control unit <NUM> drives the second detector <NUM> in the optical axis direction of the non-control light L3 while detecting the non-control light L3, acquires the second deviation amount which is the deviation amount of the position at which the non-control light L3 most converges on the image capturing surface <NUM>, from the initial position, and acquires the spread angle on the basis of the second deviation amount. Therefore, according to the mechanical driving of the second detector <NUM>, it is possible to acquire the information on the change in the spread angle of the non-control light L3.

Further, in the laser processing device <NUM>, the phase control unit <NUM> includes the spatial phase modulator <NUM> that displays the phase modulation pattern for diffracting the received laser light L1 to branch the laser light L1 into a plurality of rays of diffraction light and to emit the branched rays of diffraction light, emits Oth-order light of the laser light L1 as the non-control light L3, and emits another order diffraction light of the laser light L1 as the control light L2. The control unit <NUM> adjusts the phase modulation pattern (CGH) displayed on the spatial phase modulator <NUM> on the basis of the detection result for the non-control light L3 to correct the control state for the spatial phase of the control light L2 in the phase control unit <NUM>. In this way, in a case where the spatial phase modulator <NUM> is included and the laser light is branched into a plurality of rays by diffraction, while the Oth-order light that is not diffracted is suitably used as the non-control light, the change in the convergence state of the control light L2 can be easily corrected through the adjustment of the phase modulation pattern (the hologram) displayed on the liquid crystal layer.

The laser processing device <NUM> further includes the first detector <NUM> for detecting the control light L2 emitted from the phase control unit <NUM>. The control unit <NUM> generates the phase modulation pattern for adjusting the control state for the spatial phase of the control light L2 in the phase control unit <NUM> on the basis of the detection result of the control light L2 from the first detector <NUM> and causes the spatial phase modulator <NUM> to display the phase modulation pattern superimposed on the phase modulation pattern adjusted by the correction process. Therefore, the control state of the control light L2 can be adjusted in accordance with the change in the laser light (the control light L2) caused by something other than the laser light source <NUM> on the basis of the detection result of the control light L2.

The above embodiment describes an aspect of the present disclosure. Accordingly, the present disclosure is not limited to the aspect described above and may be arbitrarily modified. Subsequently, modification examples will be described.

<FIG> is a block diagram of a laser processing device according to a modification example. <FIG> is a schematic view of the laser processing device shown in <FIG>. The laser processing device (a laser device) 100A shown in <FIG> and <FIG> is different from the laser processing device <NUM> in that the phase control unit <NUM> further includes a polarization control element <NUM> and a polarizer <NUM> is provided in a preceding stage of the second detector <NUM> as compared with the laser processing device <NUM> according to the embodiment described above. The control unit <NUM> is omitted from the laser processing device 100A. Therefore, the functions of the control unit <NUM> described above are realized by the control unit <NUM>. In this way, the control unit can be common.

The polarization control element <NUM> is interposed between the laser light source <NUM> and the spatial phase modulator <NUM> on the optical path of the laser light L1. The polarization control element <NUM> is, for example, a λ/<NUM> wavelength plate and receives the laser light L1 emitted from the laser light source <NUM>. Then, the polarization control element <NUM> changes a polarization direction of the laser light L1 such that the received laser light L1 includes an S-polarized component and a P-polarized component and emits the changed laser light L1.

From the viewpoint of increasing the utilization efficiency of the laser light L1 in the spatial phase modulator <NUM>, as shown in <FIG>, the polarization direction of the laser light L1 is changed to have only a polarized component that is sensitive to the liquid crystal layer of the spatial phase modulator <NUM>. On the other hand, here, as shown in <FIG>, the polarization direction of the laser light L1 is changed to include both the P-polarized component and the S-polarized component. Therefore, one of the P-polarized component and the S-polarized component (for example, the P-polarized component) of the laser light L1 is subjected to the control of the spatial phase in the spatial phase modulator <NUM> and becomes the control light L2, while the other of the P-polarized component and the S-polarized component (for example, the S-polarized component) of the laser light L1 is not subjected to the control of the spatial phase in the spatial phase modulator <NUM> and becomes the non-control light L3.

The polarizer <NUM> is interposed between the mirror <NUM> and the second detector <NUM> on the optical paths of the control light L2 and the non-control light L3. The polarizer <NUM> transmits only the other of the P-polarized component and the S-polarized component (for example, the S-polarized component). Therefore, in the laser processing device 100A, a portion of the control light L2 and the non-control light L3 emitted from the phase control unit <NUM> is transmitted through the mirror <NUM> and is incident on the polarizer <NUM>, but only the non-control light L3 is transmitted through the polarizer <NUM> and is incident on the second detector <NUM>. That is, here, the second detector <NUM> detects (captures an image of) only the non-control light L3.

In the laser processing device 100A configured as described above, similarly to the laser processing device <NUM>, it is possible to control the phase control unit <NUM> in order to correct the control state for the spatial phase of the control light L2 in the phase control unit <NUM> on the basis of the detection result for the non-control light L3. Therefore, it is also possible for the laser processing device 100A to achieve the same operations and effects as the laser processing device <NUM>.

Particularly, in the laser processing device <NUM>, the phase control unit <NUM> includes the polarization control element <NUM> that changes the polarization direction of the laser light L1 such that the received laser light L1 includes the S-polarized component and the P-polarized component and emits the changed laser light L1, and the spatial phase modulator <NUM> that controls the spatial phase of one of the S-polarized component and the P-polarized component of the laser light L1 emitted from the polarization control element <NUM> to emit the one controlled polarized component as the control light L2 and to emit the other of the S-polarized component and the P-polarized component of the laser light L1 as the non-control light L3. Then, the control unit <NUM> adjusts the phase modulation pattern displayed on the spatial phase modulator <NUM> on the basis of the detection result for the non-control light L3 to correct the control state for the spatial phase of the control light L2 in the phase control unit <NUM>. Therefore, while the polarized component that is not sensitive to the liquid crystal layer is suitably used as the non-control light L3, the change in the convergence state of the control light L2 can be easily corrected through the adjustment of the phase modulation pattern (the hologram) displayed on the liquid crystal layer.

Furthermore, the laser processing device <NUM> may include a phase control unit 20A (see <FIG>) using a diffractive optical element (DOE) <NUM> instead of the phase control unit <NUM> using the liquid crystal type spatial phase modulator <NUM>.

<FIG> is a schematic view of a phase control unit according to a modification example. As shown in <FIG>, the phase control unit 20A includes a diffractive optical element <NUM>, a lens <NUM>, a lens <NUM>, a movable mirror <NUM>, and a movable mirror <NUM>. The lens <NUM>, the lens <NUM>, the movable mirror <NUM>, and the movable mirror <NUM> are disposed on the optical path of the laser light L <NUM> incident on the diffractive optical element <NUM> in this order.

The diffractive optical element <NUM> diffracts the incident laser light L1 to branch the laser light L1 into a plurality of rays of diffraction light and to emit the plurality of rays of diffraction light. The diffractive optical element <NUM> emits the Oth-order light of the laser light L1 as the non-control light L3 and emits another order diffraction light of the laser light L1 as the control light L2.

The movable mirror <NUM> is rotatable around an axis in the X-axis direction which is one direction that defines the XY plane, for example, and the movable mirror <NUM> is rotatable around an axis in the Y-axis direction which is another direction that defines the XY plane, for example. Therefore, in a case where the positional deviation of the non-control light L3 occurs within the XY plane (that is, in a case where Δx and Δy are acquired as the first deviation amount), the control unit <NUM> adjusts such that Δx and Δy become <NUM> by driving the movable mirror <NUM> and the movable mirror <NUM>. As a result, the positional deviation of the control light L2 is corrected.

Further, the lens <NUM> and the lens <NUM> constitute, for example, a Galilean telescope. A magnification ration is expressed as -(focal length f2)/(focal length f1) using a focal length f1 of the lens <NUM> and a focal length f2 of the lens <NUM>. Further, a distance d between the lens <NUM> and the lens <NUM> in the initial state is equal to the sum of the focal length f1 and the focal length f2. The lens <NUM> is movable in the optical axis direction. Therefore, in a case where the spread angle of the non-control light L3 changes (that is, in a case where the second deviation amount is acquired), the control unit <NUM> changes the position of the lens <NUM> in the optical axis direction to correct the spread angle of the control light L2.

That is, also in this modification example, the control unit <NUM> can execute the correction process of controlling the phase control unit 20A to correct the control state for the spatial phase of the control light L2 in the phase control unit 20A on the basis of the detection result for the non-control light L3 from the second detector <NUM>. More specifically, the control unit <NUM> can execute the first correction process and the second correction process as in the above embodiment.

In the phase control unit 20A, lenses 121A and 122A forming a Keplerian telescope as shown in <FIG> may be employed instead of the lenses <NUM> and <NUM> forming the Galilean telescope. A magnification ration in this case is expressed as (focal length f2)/(focal length f1) using a focal length f1 of the lens 121A and a focal length f2 of the lens 122A. Further, a distance d between the lens <NUM> and the lens <NUM> in the initial state is equal to the sum of the focal length f1 and the focal length f2.

Furthermore, in the above embodiments and modification examples, the laser processing device for processing the object A is exemplified. However, the present disclosure can also be applied to a laser device for purposes other than processing, such as a microscope.

Claim 1:
A laser device comprising:
a laser light source (<NUM>) configured to emit laser light;
characterized by a phase control unit (<NUM>) configured to receive the laser light emitted from the laser light source (<NUM>), to control a spatial phase of a portion of the laser light (L1), to emit the portion of the light as control light (L2), and to emit another portion of the laser light as non-control light (L3);
a first optical system (<NUM>) configured to irradiate an object with the control light (L2) emitted from the phase control unit (<NUM>);
a detector (<NUM>) configured to detect the non-control light (L3) emitted from the phase control unit (<NUM>);
a second optical system (<NUM>) configured to cause the non-control light (L3) emitted from the phase control unit (<NUM>) to converge toward a detection surface of the detector (<NUM>); and
a control unit (<NUM>, <NUM>) configured to execute a correction process for controlling the phase control unit (<NUM>) to correct a control state for a spatial phase of the control light (L2) in the phase control unit (<NUM>) on the basis of a detection result for the non-control light (L3) from the detector (<NUM>).