Patent Description:
A laser processing system performs laser processing such as cutting, welding, and drilling of a workpiece. In the laser processing system, a laser processing head irradiates a workpiece with a laser beam emitted from a laser oscillator and guided through an optical fiber. The laser processing head is provided with a condensing optical system for condensing the laser beam and irradiating the workpiece with the laser beam.

For example, in PTLs <NUM> and <NUM>, a laser processing system that transmits a laser beam emitted from a laser oscillator and irradiates a workpiece via a plurality of optical systems is disclosed. A laser beam emitted from an optical fiber is converted into parallel light by a collimator lens, is condensed by a condensing lens, and is applied to a front surface of the workpiece. The collimator lens and the condensing lens are provided to be movable in an optical axis direction of the laser beam. A diameter of the laser beam on the front surface of the workpiece can be converted by moving the collimator lens and the condensing lens in the optical axis direction. PTL <NUM> relates to a light modulation control method and device which control light condensing irradiation of laser light onto a light condensing point by a modulation pattern to be presented in a spatial light modulator.

In recent years, a hybrid laser processing system using two types of laser beams having wavelengths different from each other, such as near-infrared light and blue light, for example, has been known. The hybrid laser processing system combines two types of laser beams having wavelengths different from each other on an identical optical axis by a laser processing head, condenses the combined two types of laser beams, and irradiates the workpiece with the condensed laser beams. The hybrid laser processing system can utilize strengths of the laser beams and complement limitations of the laser beams, and thus has more advantages than a conventional laser processing system using only one type of laser beam.

However, in the hybrid laser processing system, since it is necessary to adjust a condensing position and a condensing state such as a spot diameter on the front surface of the workpiece for two types of laser beams having wavelengths different from each other, it is difficult to adjust the condensing state of the laser beam as compared with the laser processing system of the related art using only one type of laser beam.

Since the hybrid laser processing system handles two types of laser beams, the number of components constituting the system is often increased. In particular, there is a concern that a size of a laser processing head having a plurality of optical components therein is increased.

The present disclosure has been made in view of such a point, and an object of the present disclosure is to provide a laser processing head and a laser processing system including the laser processing head that can be downsized while condensing states of two types of laser beams having wavelengths different from each other are adjustable. Solution to problem.

A laser processing head according to the present disclosure is a laser processing head including: a housing; and a plurality of optical components disposed inside the housing. The housing includes a first light entrance port through which a first laser beam is incident, a second light entrance port through which a second laser beam having a wavelength different from the first laser beam is incident, and a light irradiation port through which the first laser beam and the second laser beam are emitted to an outside, the plurality of optical components include at least a bend mirror that is provided in an optical path of the second laser beam, and reflects the second laser beam to change the optical path, a dichroic mirror that is provided in an optical path of the first laser beam, the dichroic mirror being provided in the optical path of the second laser beam reflected by the bend mirror, an aperture that is provided in the optical paths of the second laser beam transmitted through the dichroic mirror, the aperture being provided in the optical path of the first laser beam reflected by the dichroic mirror, and a detection-side condensing lens that is provided in the optical paths of the first laser beam and the second laser beam transmitted through the aperture, a photodetector is disposed inside the housing, the photodetector being at a position where the first laser beam and the second laser beam transmitted through the detection-side condensing lens are receivable, the dichroic mirror transmits most of the first laser beam to be directed to the light irradiation port, and reflects a rest of the first laser beam to be directed to the aperture, and reflects most of the second laser beam to be directed to the light irradiation port, and transmits a rest of the second laser beam to be directed to the aperture, and the aperture is configured to be able to reduce diameters of the first laser beam and the second laser beam incident on the detection-side condensing lens.

A laser processing system according to the present disclosure includes at least the laser processing head, a first laser oscillator that emits the first laser beam, a second laser oscillator that emits the second laser beam, a first optical fiber that is connected to the first light entrance port and transmits the first laser beam emitted from the first laser oscillator to the laser processing head, and a second optical fiber that is connected to the second light entrance port and transmits the second laser beam emitted from the second laser oscillator to the laser processing head, wherein the laser processing head irradiates a workpiece with at least one of the first laser beam or the second laser beam.

According to the present disclosure, in the hybrid laser processing system, it is possible to adjust the condensing states of two types of laser beams having wavelengths different from each other. The laser processing head can be downsized.

Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings. Note that, the following descriptions of preferable exemplary embodiments are merely illustrative in nature, and are not intended to limit the scope, applications, or use of the present disclosure in any way.

<FIG> illustrates laser processing system (laser processing apparatus) <NUM> according to the present exemplary embodiment. Laser processing system <NUM> is a hybrid laser processing system using two types of laser beams having different wavelengths, and performs laser processing such as cutting, welding, and drilling of workpiece W.

Laser processing system <NUM> includes laser processing head (laser irradiation head) <NUM>, first laser oscillator <NUM> and second laser oscillator <NUM>, first optical fiber <NUM>, second optical fiber <NUM>, manipulator <NUM>, and control device <NUM>.

First laser oscillator <NUM> emits first laser beam A. Second laser oscillator <NUM> emits second laser beam B. First laser beam A and second laser beam B have different wavelengths. First laser beam A is near-infrared light having a wavelength ranging from about <NUM> to <NUM> inclusive. Second laser beam B is near-infrared light having a wavelength ranging from about <NUM> to <NUM> inclusive. In general, near-infrared light is applied to laser processing, but in recent years, blue light is also being applied to laser processing because of its good absorption rate to copper. Note that, second laser beam B may be green light (wavelength: from about <NUM> to <NUM> inclusive).

First optical fiber <NUM> transmits first laser beam A from first laser oscillator <NUM> to laser processing head <NUM>. Second optical fiber <NUM> transmits second laser beam B from second laser oscillator <NUM> to laser processing head <NUM>.

Laser processing head <NUM> irradiates front surface W1 of workpiece W with at least one of first laser beam A or second laser beam B. In this case, an optical axis of first laser beam A directed from laser processing head <NUM> toward workpiece W and an optical axis of second laser beam B are made identical. For example, in a case where front surface W1 of workpiece W is simultaneously irradiated with both first laser beam A and second laser beam B, workpiece W is irradiated with first laser beam A and second laser beam B in a state where the optical axis of first laser beam A and the optical axis of second laser beam B are overlapped with each other. Details of laser processing head <NUM> will be described later.

Laser processing head <NUM> is attached to a distal end of manipulator <NUM>, and laser processing head <NUM> is moved. Control device <NUM> controls operation of manipulator <NUM> and oscillation of laser beams A and B by laser oscillators <NUM> and <NUM>. Control device <NUM> may control operation of an actuator to be described later inside laser processing head <NUM>.

<FIG> illustrates an internal structure of laser processing head <NUM>. Note that X, Y, and Z in <FIG> indicate directions in an orthogonal coordinate system, X and Y are horizontal directions of front, rear, left, and right, and Z is an up-down direction (vertical direction). In addition, a direction in which an optical axis (virtual ray as representative of light flux in each of laser beams A and B) of each of laser beams A and B extends is referred to as an "optical axis direction". The optical axis direction is not always constant in the orthogonal coordinate systems X, Y, and Z, and may change in accordance with traveling of each of laser beams A and B.

Laser processing head <NUM> condenses first laser beam A and second laser beam B by a condensing optical system provided inside housing <NUM>, and irradiates workpiece W with first laser beam A and second laser beam B. Laser processing head <NUM> includes, as the condensing optical system, first collimator lens <NUM>, second collimator lens <NUM>, bend mirror <NUM>, dichroic mirror <NUM>, workpiece-side condensing lens <NUM>, image sensor <NUM> as a photodetector, detection-side condensing lens <NUM>, aperture <NUM>, mirror-side actuator <NUM> as a part of an adjuster, first lens-side actuator <NUM> as a part of an adjuster, and second lens-side actuator <NUM> as a part of an adjuster.

Housing <NUM> is provided with first light entrance port 12a and second light entrance port 12b on an upper side in a Z direction. First light entrance port 12a and second light entrance port 12b are provided with a predetermined space from each other. First optical fiber <NUM> is connected to first light entrance port 12a, and first laser beam A is incident on an inside of housing <NUM> through first light entrance port 12a. Second optical fiber <NUM> is connected to second light entrance port 12b, and second laser beam B is incident on the inside of housing <NUM> through second light entrance port 12b. Note that, first light entrance port 12a and second light entrance port 12b may be collectively referred to as incident portion <NUM>.

Housing <NUM> is provided with light irradiation port (irradiation part) <NUM> on a lower side in the Z direction. Front surface W1 of workpiece W is irradiated with first laser beam A and second laser beam B through protective glass (not illustrated) provided in light irradiation port <NUM>.

First collimator lens <NUM> converts first laser beam A into a parallel ray. Note that, second collimator lens <NUM> converts second laser beam B into a parallel ray. First laser beam A and second laser beam B travel straight in the Z direction in parallel with each other until first laser beam A and second laser beam B are incident on first collimator lens <NUM> and second collimator lens <NUM>, respectively.

Bend mirror <NUM> changes the optical axis of second laser beam B parallel to the optical axis of first laser beam A in a direction intersecting the optical axis of first laser beam A, specifically, to in a direction orthogonal to the optical axis of first laser beam A (Y direction).

Dichroic mirror <NUM> is a mirror that transmits most of light in a specific wavelength region and reflects most of light in the other wavelength regions. In the present exemplary embodiment, dichroic mirror <NUM> transmits most of first laser beam A incident from rear surface <NUM> substantially straight toward front surface <NUM>, and reflects most of second laser beam B incident from front surface <NUM> substantially at a right angle toward front surface <NUM>. On the other hand, dichroic mirror <NUM> reflects the rest of first laser beam A incident from rear surface <NUM> substantially at the right angle toward rear surface <NUM>, and transmits the rest of second laser beam B incident from front surface <NUM> substantially straight toward rear surface <NUM>.

Light irradiation port <NUM> is disposed on an optical axis direction traveling side of most of first laser beam A transmitted through dichroic mirror <NUM> and most of second laser beam B reflected by dichroic mirror <NUM>. That is, dichroic mirror <NUM> transmits most of first laser beam A toward workpiece W and reflects most of second laser beam B toward workpiece W.

Note that, most of each of laser beams A and B is, for example, about <NUM>% to <NUM>% of each of laser beams A and B before being incident on dichroic mirror <NUM> in terms of energy. The rest of each of laser beams A and B is, for example, about <NUM>% to <NUM>% of each of laser beams A and B before being incident on dichroic mirror <NUM> in terms of energy.

Workpiece-side condensing lens <NUM> is disposed between dichroic mirror <NUM> and workpiece W in the optical axis direction. Workpiece-side condensing lens <NUM> condenses each of first laser beam A and second laser beam B. Front surface W1 of workpiece W is irradiated with condensed first laser beam A and second laser beam B through light irradiation port <NUM>. Workpiece-side condensing lens <NUM> may have a chromatic aberration correction function. In this case, condensing positions of first laser beam A and second laser beam B transmitted through workpiece-side condensing lens <NUM> substantially coincide with each other in the Z direction.

Image sensor (photodetector) <NUM> is an imaging element that photoelectrically converts brightness and darkness of light formed on light receiving surface <NUM> into an amount of charge, reads the charge, and converts the charge into an electric signal. Image sensor <NUM> is disposed on a side of rear surface <NUM> of dichroic mirror <NUM>. Specifically, image sensor <NUM> is disposed on the advancing side in the optical axis direction of the rest of first laser beam A reflected by dichroic mirror <NUM> and the rest of second laser beam B transmitted through dichroic mirror <NUM>. That is, image sensor <NUM> receives the rest of first laser beam A reflected by dichroic mirror <NUM> and the rest of second laser beam B transmitted through dichroic mirror <NUM> on light receiving surface <NUM>.

Aperture <NUM> is disposed between dichroic mirror <NUM> and detection-side condensing lens <NUM> in the optical axis direction. As will be described in detail later, aperture <NUM> is configured to be able to reduce diameters of first laser beam A and second laser beam B (hereinafter, may be referred to as a beam diameter of first laser beam A and a beam diameter of second laser beam B, respectively) incident on detection-side condensing lens <NUM>.

Detection-side condensing lens <NUM> is disposed between aperture <NUM> and image sensor <NUM> in the optical axis direction. Detection-side condensing lens <NUM> condenses each of first laser beam A and second laser beam B. Detection-side condensing lens <NUM> irradiates light receiving surface <NUM> of image sensor <NUM> with each of condensed first laser beam A and second laser beam B. Detection-side condensing lens <NUM> may have a chromatic aberration correction function. In this case, condensing positions of first laser beam A and second laser beam B transmitted through detection-side condensing lens <NUM> substantially coincide with each other in the Y direction.

A size and curvature of detection-side condensing lens <NUM> and a distance between detection-side condensing lens <NUM> and image sensor <NUM> are set so as to correspond to a condensing state of first laser beam A with which front surface W1 of workpiece W is irradiated. That is, the condensing state of first laser beam A with which light receiving surface <NUM> of image sensor <NUM> is irradiated corresponds to the condensing state of first laser beam A with which front surface W1 of workpiece W is irradiated.

Similarly, the size and curvature of detection-side condensing lens <NUM> and the distance between detection-side condensing lens <NUM> and image sensor <NUM> are set so as to correspond to a condensing state of second laser beam B with which front surface W1 of workpiece W is irradiated. That is, the condensing state of second laser beam B with which light receiving surface <NUM> of image sensor <NUM> is irradiated corresponds to the condensing state of second laser beam B with which front surface W1 of workpiece W is irradiated.

For example, when a spot diameter (detection-side first spot diameter Daj) of first laser beam A increases on light receiving surface <NUM> of image sensor <NUM>, a spot diameter (workpiece-side first spot diameter Dai) of first laser beam A with which front surface W1 of workpiece W is irradiated also increases. When the condensing position of second laser beam B is shifted on light receiving surface <NUM> of image sensor <NUM>, the condensing position of second laser beam B with which front surface W1 of workpiece W is irradiated is also shifted. Note that, in the present exemplary embodiment, the "spot diameter" means a diameter of a laser beam on any image plane (for example, front surface W1 of workpiece W or light receiving surface <NUM> of image sensor <NUM>), and is not necessarily limited to a diameter at a converging spot of the laser beam.

Mirror-side actuator <NUM> changes an inclination of bend mirror <NUM>. Mirror-side actuator <NUM> includes, for example, a tilt shaft and a motor that rotates the tilt shaft. A change of inclination of bend mirror <NUM> by mirror-side actuator <NUM> changes a direction of the optical axis of second laser beam B bent by bend mirror <NUM>. As a result, the condensing position of second laser beam B changes.

First lens-side actuator <NUM> moves first collimator lens <NUM> in the optical axis direction (Z direction). First lens-side actuator <NUM> includes, for example, a linear motor. Second lens-side actuator <NUM> moves second collimator lens <NUM> in the optical axis direction (Z direction). Second lens-side actuator <NUM> includes, for example, a linear motor. The movement of each of collimator lenses <NUM> and <NUM> in the optical axis direction (Z direction) by each of lens-side actuators <NUM> and <NUM> changes spot diameters of first laser beam A and second laser beam B to be described later.

Note that, when each of collimator lenses <NUM> and <NUM> is moved in the optical axis direction (Z direction) by each of lens-side actuators <NUM> and <NUM>, each of collimator lenses <NUM> and <NUM> does not necessarily move straight in the optical axis direction (Z direction), but may slightly move or slightly tilt in the horizontal direction (X direction and Y direction) orthogonal to the optical axis direction.

<FIG> schematically illustrates a change in the beam diameter of the first laser beam by the aperture, and <FIG> schematically illustrates a change in the beam diameter of the second laser beam by the aperture.

In a case where a maximum opening diameter of aperture <NUM> is larger than each of beam diameter φ1 of first laser beam A and beam diameter φ3 of second laser beam B, as illustrated on a left side of <FIG> and a left side of <FIG>, first laser beam A and second laser beam B are incident on detection-side condensing lens <NUM> in a state where original beam diameters are maintained.

However, outputs of first laser beam A and second laser beam B used for laser processing are usually as large as several hundred W to several kW. Accordingly, even though about <NUM>% of these outputs are incident on image sensor <NUM>, the power of the laser beam with which light receiving surface <NUM> is irradiated reaches several W to several ten W. In this case, the output is too large, and the image acquired by image sensor <NUM> may cause disturbance such as halation, or a color filter or the like of image sensor <NUM> may be baked at the time of long-term use. It is necessary to set the size of detection-side condensing lens <NUM> such that beam diameter φ1 or beam diameter φ3 falls within an effective condensing diameter of detection-side condensing lens <NUM>. When beam diameter φ1 or beam diameter φ3 is larger than a predetermined value, detection-side condensing lens <NUM> becomes large.

Therefore, the opening diameter of aperture <NUM> is appropriately narrowed, and thus, the beam diameters of first laser beam A and second laser beam B are reduced to φ2 (φ2 < φ1, φ3) as illustrated on the left side of <FIG> and the left side of <FIG>. In this way, the diameters of first laser beam A and second laser beam B incident on detection-side condensing lens <NUM> can be reduced and adjusted to fall within the effective condenser diameter of detection-side condensing lens <NUM>. That is, it is possible to suppress an increase in the size of detection-side condensing lens <NUM>, and eventually laser processing head <NUM>.

The opening diameter of aperture <NUM> is narrowed, and thus, it is possible to block excessive light fluxes of first laser beam A and second laser beam B and to cause the light fluxes to be incident on light receiving surface <NUM> of image sensor <NUM>. As a result, it is possible to reduce the power of first laser beam A and second laser beam B incident on light receiving surface <NUM> and to suppress the occurrence of the above-described problems such as image disturbance and image burn-in of a color filter or the like.

<FIG> schematically illustrates a pixel structure of the image sensor. <FIG> illustrates a relationship between light receiving efficiency and a wavelength of an RGB pixel. <FIG> schematically illustrates another pixel structure of the image sensor.

As illustrated in <FIG>, image sensor <NUM> has arrays in units of a total of four pixels including a pixel that receives near-infrared light or infrared light (hereinafter, referred to as an N pixel), a pixel that receives red light (hereinafter, referred to as an R pixel), a pixel that receives green light (hereinafter, referred to as a G pixel), and a pixel that receives blue light (hereinafter, referred to as a B pixel). Specifically, the array is a color filter array in which one G pixel is replaced with the N pixel as compared with a known Bayer array.

As illustrated in <FIG>, the R pixel has high quantum efficiency of photoelectrically converting light having a wavelength band ranging from about <NUM> to <NUM> inclusive, and efficiently converts light of normal red light (from about <NUM> to <NUM> inclusive) into an electrical signal. The G pixel has high quantum efficiency of photoelectrically converting light having a wavelength band ranging from about <NUM> to <NUM> inclusive, and efficiently converts light of normal green light (from about <NUM> to <NUM> inclusive) into an electrical signal. The B pixel has high quantum efficiency of photoelectrically converting light having a wavelength band ranging from about <NUM> to <NUM> inclusive, and efficiently converts light of normal blue light (from about <NUM> to <NUM> inclusive) into an electrical signal. Note that, although not illustrated, the N pixel has high quantum efficiency of photoelectrically converting light having a wavelength band ranging from about <NUM> to <NUM> inclusive, and efficiently converts light of near-infrared light or infrared light (from about <NUM> to <NUM> inclusive) into an electrical signal.

As described above, a wavelength of first laser beam A ranges from about <NUM> to <NUM> inclusive, and a wavelength of second laser beam B ranges from about <NUM> to <NUM> inclusive. Thus, due to the use of image sensor <NUM> illustrated in <FIG>, first laser beam A and second laser beam B transmitted through detection-side condensing lens <NUM> can be reliably converted into electric signals. A size of each pixel is appropriately set, and thus, it is possible to grasp a two-dimensional distribution of each of first laser beam A and second laser beam B on light receiving surface <NUM>. As will be described later, the condensing positions and spot diameters of first laser beam A and second laser beam B on front surface W1 of workpiece W can be corrected based on the two-dimensional distribution and the spot diameters of first laser beam A and second laser beam B on light receiving surface <NUM>.

Note that, from the viewpoint of reliably converting each of first laser beam A and second laser beam B into an electric signal, only two types of B pixels and N pixels may be periodically arrayed as illustrated in <FIG>. In a case where second laser beam B is green light, the B pixels may be replaced with the G pixels in <FIG>. That is, image sensor <NUM> includes a plurality of first light receivers (N pixels) that receive light rays in a first wavelength band including the wavelength of first laser beam A, for example, <NUM> to <NUM>. Image sensor <NUM> includes a plurality of second light receivers (B pixels and/or G pixels) that receive light rays in a second wavelength band including the wavelength of second laser beam B, for example, <NUM> to <NUM>. The image sensor may have a pixel structure in which a plurality of first light receivers and a plurality of second light receivers are periodically arrayed on light receiving surface <NUM>.

In a case where laser processing is actually performed on workpiece W, it is not possible to monitor the condensing state of each of first laser beam A and second laser beam B on front surface W1. On the other hand, in the present exemplary embodiment, as described above, the condensing states of first laser beam A and second laser beam B with which light receiving surface <NUM> of image sensor <NUM> is irradiated correspond to the condensing states of first laser beam A and second laser beam B with which front surface W1 of workpiece W is irradiated. That is, the condensing state on front surface W1 of workpiece W can be monitored based on spot images (see, for example, <FIG>) of first laser beam A and second laser beam B with which light receiving surface <NUM> of image sensor <NUM> is irradiated.

In a case where the condensing position of first laser beam A and the condensing position of second laser beam B are shifted due to a misalignment of the optical axes of two laser beams, for example, mirror-side actuator <NUM> can be tilted to cause the condensing positions of two laser beams to coincide with each other. For example, in a case where the spot image of first laser beam A with which light receiving surface <NUM> of image sensor <NUM> is irradiated is defocused, first lens-side actuator <NUM> is driven to cancel a defocus state. In this way, first laser beam A can be focused on front surface W1 of workpiece W. Similarly, in a case where the spot image of second laser beam B with which light receiving surface <NUM> of image sensor <NUM> is irradiated is defocused, second lens-side actuator <NUM> is driven to cancel a defocus state. In this way, second laser beam B can be focused on front surface W1 of workpiece W.

As described above, laser processing head <NUM> according to the present exemplary embodiment includes housing <NUM> and a plurality of optical components disposed inside housing <NUM>.

First light entrance port 12a through which first laser beam A is incident, second light entrance port 12b through which second laser beam B is incident, and light irradiation port <NUM> through which first laser beam A and second laser beam B are emitted to the outside are provided in housing <NUM>. Second laser beam B has a shorter wavelength than first laser beam A.

The plurality of optical components include at least bend mirror <NUM> that is provided in an optical path of second laser beam B and reflects second laser beam B to change the optical path, and dichroic mirror <NUM> that is provided in an optical path of first laser beam A and in the optical path of second laser beam B reflected by bend mirror <NUM>.

The plurality of optical components include aperture <NUM> that is provided in the optical path of second laser beam B transmitted through dichroic mirror <NUM> and in the optical path of first laser beam A reflected by dichroic mirror <NUM>, and detection-side condensing lens <NUM> provided in the optical paths of first laser beam A and second laser beam B transmitted through aperture <NUM>.

Image sensor (photodetector) <NUM> is disposed inside housing <NUM> at a position where first laser beam A and second laser beam B transmitted through detection-side condensing lens <NUM> are receivable.

Dichroic mirror <NUM> transmits most of first laser beam A to be directed to light irradiation port <NUM>, and reflects the rest of first laser beam A to be directed to aperture <NUM>. Aperture <NUM> transmits most of second laser beam B to be directed to light irradiation port <NUM>, and reflects the rest of second laser beam B to be directed to aperture <NUM>.

Aperture <NUM> is configured to be able to reduce the diameters of first laser beam A and second laser beam B incident on detection-side condensing lens <NUM>.

Aperture <NUM> is a diaphragm jig for first laser beam A and second laser beam B, and usually, a thickness in the optical axis direction may be thin, and a size in the diameter direction (Z direction in <FIG>) of the laser beam may be any size as long as first laser beam A and second laser beam B can pass through the aperture. On the other hand, in a case where the diameter of detection-side condensing lens <NUM> is increased such that first laser beam A and second laser beam B fall within an effective diameter, it is necessary to change the curvature and the like. In the example illustrated in <FIG>, a thickness in the Y direction may greatly increase.

According to the present exemplary embodiment, aperture <NUM> is provided, and thus, the diameters of first laser beam A and second laser beam B incident on detection-side condensing lens <NUM> can be reduced. Accordingly, it is possible to suppress an increase in the size of detection-side condensing lens <NUM> and eventually laser processing head <NUM>.

The opening diameter of aperture <NUM> is narrowed, and thus, it is possible to block excessive light fluxes of first laser beam A and second laser beam B and to cause the light fluxes to be incident on light receiving surface <NUM> of image sensor <NUM>. As a result, it is possible to reduce the power of first laser beam A and second laser beam B incident on light receiving surface <NUM> and to suppress the occurrence of the above-described problems such as image disturbance and image burn-in of a color filter or the like. This will be further described.

<FIG> illustrates an example of the spot image of the first laser beam and the second laser beam condensed on the light receiving surface of the image sensor, and <FIG> illustrates an example of the spot image of the first laser beam and the second laser beam condensed on the front surface of the workpiece. <FIG> illustrates a diagram corresponding to <FIG> according to a comparative example, and <FIG> illustrates a diagram corresponding to <FIG> according to the comparative example. Note that, <FIG> correspond to a case where aperture <NUM> is not provided in laser processing head <NUM> or aperture <NUM> is not operated.

An arrangement relationship between the optical components inside laser processing head <NUM> is appropriately set, and thus, first laser beam A and second laser beam B are condensed to coincide with each other or be in proximity to each other on front surface W1 of workpiece W as illustrated in <FIG> and <FIG>. Workpiece-side first spot Sai of first laser beam A and workpiece-side second spot Sbi of second laser beam B are both adjusted to have sizes suitable for processing. Workpiece-side first spot diameter Dai of first laser beam A and workpiece-side second spot diameter Dbi of second laser beam B are both adjusted to have sizes suitable for processing.

However, in a case where aperture <NUM> is not provided in laser processing head <NUM>, as described above, the power of each of first laser beam A and second laser beam B incident on light receiving surface <NUM> of image sensor <NUM> may become too large. In this case, for example, as illustrated in <FIG>, halation occurs on an imaging screen, and it is difficult to clearly separate and identify detection-side first spot Saj of first laser beam A and detection-side second spot Sbj of second laser beam A.

On the other hand, according to the present exemplary embodiment, aperture <NUM> is provided in laser processing head <NUM>, and thus, the power and the diameter of each of first laser beam A and second laser beam B incident on detection-side condensing lens <NUM> can be appropriately reduced. In this case, for example, as illustrated in <FIG>, the occurrence of halation or the like can be eliminated, and the disturbance of the image can be suppressed. Detection-side first spot Saj of first laser beam A and detection-side second spot Sbj of second laser beam A can be clearly separated and identified. Detection-side first spot diameter Daj of first laser beam A and detection-side second spot diameter Dbj of second laser beam A can be measured. It is possible to suppress occurrence of problems such as image burn-in of the color filter and the like as described above. As a result, the condensing positions of first laser beam A and second laser beam B on front surface W1 of workpiece W can be adjusted based on images of first laser beam A and second laser beam B acquired by image sensor <NUM>.

Inside housing <NUM>, first collimator lens <NUM> is provided between first light entrance port 12a and dichroic mirror <NUM> in the Z direction. Second collimator lens <NUM> is provided between second light entrance port 12b and bend mirror <NUM>. Workpiece-side condensing lens <NUM> is provided between dichroic mirror <NUM> and light irradiation port <NUM>.

First collimator lens <NUM> collimates first laser beam A and causes collimated first laser beam A to be incident on dichroic mirror <NUM>. Second collimator lens <NUM> collimates second laser beam B and causes collimated second laser beam B to be incident on bend mirror <NUM>. Workpiece-side condensing lens <NUM> condenses each of incident first laser beam A and second laser beam B at predetermined condensing positions.

In the present exemplary embodiment, the above configuration can make the optical axis of first laser beam A and the optical axis of second laser beam B directed from light irradiation port <NUM> to workpiece W substantially coincide with each other. First laser beam A and second laser beam B can be focused on front surface W1 of workpiece W. As a result, the condensing positions of first laser beam A and second laser beam B on front surface W1 of workpiece W can be made substantially coincide with each other.

Image sensor (photodetector) <NUM> includes at least a plurality of first light receivers that receive light rays in a first wavelength band including the wavelength of first laser beam A and a plurality of second light receivers that receive light rays in a second wavelength band including the wavelength of second laser beam B. The plurality of first light receivers and the plurality of second light receivers are periodically arrayed on light receiving surface <NUM> of image sensor <NUM>.

Such a configuration of image sensor <NUM> makes it possible to acquire the spot images of first laser beam A and second laser beam B with high resolution. As a result, the condensing positions of first laser beam A and second laser beam B on front surface W1 of workpiece W can be adjusted precisely.

Image sensor <NUM> preferably has a structure in which four pixels that respectively receive near-infrared light or infrared light, red light, green light, and blue light are periodically arrayed on light receiving surface <NUM>.

This pixel structure, which is a known configuration and does not use a photodetector having a special structure, can suppress an increase in cost of laser processing head <NUM>. Since an output signal of image sensor <NUM> can be processed by using a known signal processing device, an increase in a load of signal processing can be suppressed.

Laser processing system (laser processing apparatus) <NUM> according to the present exemplary embodiment includes at least laser processing head <NUM>, first laser oscillator <NUM> that emits first laser beam A, and second laser oscillator <NUM> that emits second laser beam B.

Laser processing system <NUM> further includes first optical fiber <NUM> that is connected to first light entrance port 12a and transmits first laser beam A emitted from first laser oscillator <NUM> to laser processing head <NUM>, and second optical fiber <NUM> that is connected to second light entrance port 12b and transmits second laser beam B emitted from second laser oscillator <NUM> to laser processing head <NUM>.

Laser processing head <NUM> irradiates workpiece W with at least one of first laser beam A or second laser beam B.

In the present exemplary embodiment, the condensing positions of first laser beam A and second laser beam B on front surface W1 of workpiece W can be made substantially coincide with each other. As a result, in a case where laser processing is performed on workpiece W in a state where first laser beam A and second laser beam B are superimposed on each other, processing accuracy and processing quality can be improved.

Laser processing system <NUM> may further include manipulator <NUM> that movably holds laser processing head <NUM>. In this way, laser processing can be easily performed on workpiece W having a complicated structure.

In laser processing system <NUM>, the condensing positions of first laser beam A and second laser beam B on front surface W1 of workpiece W can be adjusted based on the images of first laser beam A and second laser beam B acquired by image sensor <NUM>. In this way, it is easy to set the condensing positions of first laser beam A and second laser beam B on front surface W1 of workpiece W to desired positions. As a result, this configuration can improve the processing accuracy and processing quality during the laser processing.

<FIG> schematically illustrates a main part of an internal structure of a laser processing head according to the present modification.

Laser processing head <NUM> of the present modification illustrated in <FIG> is different from the laser processing head illustrated in <FIG> in that light reducing filter <NUM> is disposed between aperture <NUM> and detection-side condensing lens <NUM>.

As described above, the outputs of first laser beam A and second laser beam B may reach several kW. Note that, depending on reflectance (transmittance) of first laser beam A and second laser beam B in dichroic mirror <NUM>, even though an excessive light flux is blocked by aperture <NUM>, the power of first laser beam A and second laser beam B may become too large on light receiving surface <NUM> of image sensor <NUM>.

In such a case, light reducing filter <NUM> is provided as illustrated in <FIG>, and thus, the power of first laser beam A and second laser beam B incident on light receiving surface <NUM> of image sensor <NUM> can be reduced. As a result, it is possible to reduce the occurrence of problems such as image burn-in of image sensor <NUM>. Even at the time of long-term use, it is possible to acquire clear images of detection-side first spot Saj of first laser beam A and detection-side second spot Sbj of second laser beam B.

Note that, the characteristics of light reducing filter <NUM> are set so as to reduce light having the same wavelength as first laser beam A and second laser beam B at a predetermined ratio. On the other hand, in laser processing system <NUM>, first laser beam A is often set to have a larger output than second laser beam B. Thus, light reducing filter <NUM> may reduce only light having the same wavelength as first laser beam A. That is, light reducing filter <NUM> is configured to reduce at least light having the same wavelength as first laser beam A.

Note that, as indicated by a broken line in <FIG>, light reducing filter <NUM> may be disposed between dichroic mirror <NUM> and aperture <NUM>.

In the present modification, aperture <NUM> between dichroic mirror <NUM> and image sensor <NUM> is provided, and thus, the diameters of first laser beam A and second laser beam B incident on detection-side condensing lens <NUM> can be reduced. As a result, it is possible to suppress an increase in the size of detection-side condensing lens <NUM> and eventually laser processing head <NUM>.

Claim 1:
A laser processing head comprising:
a housing; and
a plurality of optical components disposed inside the housing,
wherein
the housing includes
a first light entrance port through which a first laser beam is incident,
a second light entrance port through which a second laser beam having a wavelength different from the first laser beam is incident, and
a light irradiation port through which the first laser beam and the second laser beam are emitted to an outside,
the plurality of optical components include at least
a bend mirror that is provided in an optical path of the second laser beam, and reflects the second laser beam to change the optical path,
a dichroic mirror that is provided in an optical path of the first laser beam, the dichroic mirror being provided in the optical path of the second laser beam reflected by the bend mirror,
an aperture that is provided in the optical paths of the second laser beam transmitted through the dichroic mirror, the aperture being provided in the optical path of the first laser beam reflected by the dichroic mirror, and
a detection-side condensing lens that is provided in the optical paths of the first laser beam and the second laser beam transmitted through the aperture,
a photodetector is disposed inside the housing, the photodetector being at a position where the first laser beam and the second laser beam transmitted through the detection-side condensing lens are receivable,
the dichroic mirror
transmits most of the first laser beam to be directed to the light irradiation port, and reflects a rest of the first laser beam to be directed to the aperture, and
reflects most of the second laser beam to be directed to the light irradiation port, and transmits a rest of the second laser beam to be directed to the aperture, and
the aperture is configured to be able to reduce diameters of the first laser beam and the second laser beam incident on the detection-side condensing lens.