JP5997522B2 - Optical scanning apparatus and laser processing apparatus - Google Patents

Description

  The present invention relates to an optical scanning device that scans laser light along a scanning line, and a laser processing device including such an optical scanning device, and in particular, is set on a workpiece after reflecting the angularly moving laser light. The present invention relates to an optical scanning device configured to scan a laser beam along a scanning line.

  In a thin film solar cell manufacturing factory, a laser processing apparatus may be used to perform patterning on a workpiece (an intermediate product of a solar cell) formed by forming a semiconductor film on one side of a glass substrate. In patterning using a laser processing apparatus, laser light is scanned along a linear scanning line set on a workpiece, and a thin film layer of the workpiece is partially peeled off along the scanning line. Thus, in the patterning process, a plurality of linear grooves are formed on one side of the workpiece.

  A laser processing apparatus for patterning includes an optical scanning device that scans laser light from a laser oscillator along a scanning line. In general, an optical scanning device includes a deflector that reflects laser light from a laser oscillator at a deflection center and angularly moves around the deflection center at a constant speed.

  When scanning a laser beam along a linear scanning line using a deflector, the laser beam continues to be focused as much as possible on the scanning line, both the deflection speed and the scanning speed are constant, and the laser light It is required that the angle of incidence on the workpiece is as vertical as possible. In the patterning processing application, if these are not ensured, processing unevenness becomes obvious, and therefore, countermeasures are particularly required. As an optical element for solving these problems, an fθ lens is well known. However, since the fθ lens is expensive and difficult to enlarge, it is very difficult to apply the fθ lens to a laser processing apparatus for patterning. It is.

  Therefore, an optical scanning device configured to reflect the laser beam from the deflector with a mirror and guide it to the workpiece has been proposed (for example, see Patent Document 1). In Patent Document 1, a polygon mirror is applied to a deflector, and the mirror is disposed on the side opposite to the workpiece as viewed from the polygon mirror. The laser beam from the polygon mirror is first directed to the side opposite to the workpiece, then reflected by the mirror and then incident on the workpiece.

JP2011-000625A

  When the mirror is applied in this way, when the optical scanning device is projected onto the orthogonal plane of the rotation axis of the polygon mirror in the direction of the rotation axis of the polygon mirror, the optical path of the laser beam from the mirror to the workpiece passes through the polygon mirror. Naturally, since the optical path cannot interfere with the polygon mirror, in order to realize an optical scanning device to which the mirror is applied, the laser beam passes on a plane inclined with respect to the orthogonal plane, and the polygon is mirrored. Mirrors and mirrors must be placed. However, in placing the optical element, not only the position in the two axial directions defining the orthogonal plane, but also the position in the axial direction perpendicular to the plane and the posture around the two axes defining the orthogonal plane. Must be managed, and the work of arranging the elements becomes extremely complicated.

  In particular, in a laser processing apparatus for patterning processing, since the tolerance on the optical arrangement is too small compared to the size of the apparatus, there is a strong demand for a method for realizing the optical arrangement with ease and high accuracy. Moreover, the above problem becomes more prominent when the number of mirrors is increased.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an optical scanning device and a laser processing apparatus equipped with the optical scanning device so that optical devices constituting the optical scanning device can be easily and accurately arranged.

  The present invention has been made to achieve the above object. An optical scanning device according to the present invention includes a light projecting unit that emits light while angularly moving the light, and one or more reflecting units that reflect the light emitted from the light projecting unit and guide the light onto a predetermined scanning line. And at least one of the one or more reflecting portions includes a right-angle prism having a hypotenuse surface, a first boundary surface, and a second interface surface, and light incident on the right-angle prism passes through the hypotenuse surface. Reflected by the first boundary surface, reflected by the second boundary surface, passed through the hypotenuse surface, emitted from the right-angle prism, and projected onto a plane through which the rotation axis of the angular movement of light in the light projecting unit passes. In this case, the incident light path to the right-angle prism is parallel to the output light path from the right-angle prism.

  According to the above configuration, the incident optical path and the outgoing optical path need not have a component in the direction in which the rotation axis extends. Therefore, the alignment operation of the incident optical path and the outgoing optical path is simplified, and as a result, the alignment operation of the device constituting the reflecting portion can be performed easily and with high accuracy.

  The light projecting unit has a reflective deflecting unit that reflects and deflects light, and includes a deflector that emits light while rotating the light from the reflective deflecting unit by rotation, and the reflective deflecting unit of the deflector also includes A right-angle prism having a hypotenuse surface, a first boundary surface, and the second boundary surface may be provided.

  According to the said structure, a light projection part can also be arrange | positioned simply and with high precision, and an optical scanning device can be manufactured still more easily.

  The right-angle prism is applied to each of the light projecting section and the one or more reflection sections, and the oblique sides of the right-angle prism are arranged in parallel to each other, and the light projection section and the one or more reflection sections are arranged. The parts may be arranged away from each other in the direction of the rotation axis.

  According to the said structure, all the light projection parts and the reflection parts can be arrange | positioned simply and with high precision, Furthermore, the optical path which goes to a light projection part, the optical path which goes to a reflection part from a light projection part, and reflection parts go back and forth. It is possible to prevent the optical path from the reflection part and the optical path from the reflection part to the scanning line from interfering with devices constituting the light projection part and the reflection part.

  The angle formed by the oblique side surface and the first boundary surface, and the angle formed by the oblique side surface and the second boundary surface may be 45 degrees.

  According to the above configuration, it is possible to easily realize the arrangement of the incident optical path and the outgoing optical path as described above.

  The right angle prism may have a critical angle of 45 degrees or less.

  According to the above configuration, since the light can be totally reflected at the first boundary surface and the second boundary surface, the reflection portion can be prevented from being damaged by the energy of the light, and in the vicinity of the scanning line. The energy of light can be kept high.

  A laser processing apparatus according to the present invention includes the above-described optical scanning device, and processes a workpiece with the laser light from the optical scanning device to form a groove along the scanning line in the workpiece. According to such a laser processing apparatus, since the apparatus which comprises an optical scanning device can be arrange | positioned simply and with high precision, a laser processing apparatus can be manufactured simply and operation reliability of a laser processing apparatus Can be high.

  As is apparent from the above description, according to the present invention, in providing an optical scanning device and a laser processing apparatus including the optical scanning device, it is possible to easily and accurately arrange optical devices constituting the optical scanning device. .

1 is a perspective view schematically showing a laser processing apparatus according to an embodiment of the present invention. It is a conceptual diagram which shows the schematic structure of the optical scanning part shown in FIG. FIG. 3 is a perspective view of the polygon mirror shown in FIG. 2. FIG. 3 is a conceptual diagram of an optical scanning head in which the polygon mirror, the primary light reflecting portion, and the secondary light reflecting portion shown in FIG. 2 are projected onto a plane through which the rotation axis of the polygon mirror passes. It is a conceptual diagram which shows the positional relationship of the deflection | deviation center shown in FIG. 2, a primary light reflection part, a secondary light reflection part, and a scanning line.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same or corresponding elements are denoted by the same reference numerals throughout all the drawings, and detailed description thereof is omitted. In the following description, the case where the laser processing apparatus 1 is used for patterning, which is one of the manufacturing processes of a thin film solar cell, and the workpiece 90 is an intermediate product of the thin film solar cell will be exemplified. The workpiece 90 is manufactured by forming a semiconductor thin film layer 92 on one surface of a substrate 91.

  In the following description, for convenience of explanation, of the two surfaces of the plate-like or sheet-like workpiece 90, the surface 90a on the side where the thin film layer 92 is formed is referred to as a “first surface” and vice versa. The side surface 90b is referred to as a “second surface”. The first surface 90 a of the work 90 is formed by the surface of the thin film layer 92, and the second surface 90 b of the work 90 is formed by the surface opposite to the one surface of the substrate 91.

[First Embodiment]
(Laser processing equipment)
FIG. 1 is a perspective view schematically showing a laser processing apparatus 1 according to an embodiment of the present invention. As shown in FIG. 1, the laser processing apparatus 1 has a support portion 2 and an optical scanning portion 3. The support unit 2 has a function of supporting at least the workpiece 90. For example, the workpiece 90 is supported in a horizontal posture. The support unit 2 may further have a function of transporting in one horizontal direction while supporting the workpiece 90.

  The optical scanning unit 3 includes a laser oscillator 4 and an optical scanning head 5. The laser oscillator 4 sequentially oscillates pulsed laser light at a frequency in the order of kilohertz to megahertz, and emits the generated laser light to the optical scanning head 5. The optical scanning head 5 deflects the laser light from the laser oscillator 4 and irradiates the workpiece 90 with the laser light that is angularly moved. The laser beam from the optical scanning unit 3 (optical scanning head 5) is scanned linearly on the workpiece 90. As a result, the portion of the thin film layer 92 along the scanning line of the laser beam (see the one-dot chain line in FIG. 1) is peeled off from the substrate 91, and a linear groove (see the thick line in FIG. 1) is formed in the work 90. The In the patterning process, a plurality of grooves are formed in the workpiece 90 in order to configure a circuit in the solar cell.

  In the patterning process using the laser processing apparatus 1 according to the present embodiment, the laser beam is incident on the second surface 90b of the work 90 and is focused in the work 90, and the thin film layer 92 is caused by the microexplosion effect generated near the focus. Is peeled off from the substrate 91. In the present embodiment, at the time of processing, the workpiece 90 is supported with the first surface 90a facing up and the second surface 90b facing down. For this reason, the optical scanning unit 3 is configured and arranged to emit laser light upward from below the support unit 2. This configuration and arrangement is merely an example, and when the second surface 90a is directed upward, the optical scanning unit 3 is configured and arranged to emit laser light downward from above the support unit 2. May be.

  Hereinafter, for simplification of description, it is assumed that the grooves formed by patterning and the scanning line of the laser beam on the workpiece 90 at the time of patterning extend in parallel to the width direction of the workpiece 90. The extending direction of the scanning line is called “scanning direction”. A plurality of grooves formed by patterning are arranged in parallel to the vertical direction (direction perpendicular to the width direction) of the rectangular flat plate-like workpiece 90, and the direction in which the grooves are arranged is referred to as an “alignment direction”.

  As described above, the support unit 2 can have a function of conveying the workpiece 90. When one groove is formed in the workpiece 90 while the workpiece 90 is stationary, the scanning direction of the ground is the same as the scanning direction with the viewpoint on the workpiece 90. When one groove is formed in the workpiece 90 while conveying the workpiece 90 in the vertical direction (alignment direction) at a constant speed, the scanning direction with the viewpoint on the workpiece 90 coincides with the width direction of the workpiece 90. The ground scanning direction extends in a direction inclined by a certain inclination angle with respect to the width direction of the workpiece 90. The inclination angle is obtained from the conveyance speed of the workpiece 90 and the scanning speed of the laser beam. Hereinafter, for simplification of explanation, it is assumed that one groove is formed in the work 90 while the work 90 is stationary, and the scanning direction of the ground is collectively referred to as the scanning direction with the work 90 as a viewpoint. This will be described as “scanning direction”. The case where the groove is formed in the workpiece 90 while the workpiece 90 is being conveyed is similar to the configuration described below if the configuration described below is appropriately changed while considering the inclination angle as described above. Detailed description is omitted.

(Optical scanning head)
FIG. 2 is a schematic diagram illustrating the configuration of the optical scanning unit 3. The optical scanning unit 3 includes the laser oscillator 4 and the optical scanning head 5 as described above. The optical scanning head 5 includes a housing 10 incorporating a plurality of optical elements, and a plurality of optical elements or optical units constituting an optical system that scans laser light. For example, in such an optical element or optical unit, the lens 11, the prism 12, the first folding mirror 13, the second folding mirror 14, the light projecting unit 15, the light are sequentially arranged from the beam oscillator 4 along the optical path of the laser beam. A reflecting portion 16 and a cylindrical lens 17 are included. FIG. 2 illustrates the case where the housing 10 houses the second folding mirror 14, the light projecting unit 15, the light reflecting unit 16, and the cylindrical lens 17, but this is only an example. The lens 11, the prism 12, and the first folding mirror 13 may be disposed in the housing 10, and the cylindrical lens 17 may be disposed outside the housing 10.

  The lens 11 is an optical element that enables the beam light generated by the laser oscillator 4 to be focused. The prism 12, the first folding mirror 13, and the second folding mirror 14 guide the laser light that has passed through the lens 11 to the light projecting unit 15. These elements 12 to 14 constitute an optical unit that bends the optical path so as to secure an optical path length necessary for focusing the laser beam by the work 90 on the upstream side of the light path from the light projecting unit 15. These elements 12 to 14 can be omitted as appropriate, and other prisms or mirrors may be appropriately added between the lens 11 and the light projecting unit 15.

  The light projecting unit 15 is a unit that radiates the laser light incident from the upstream side of the optical path (that is, the laser oscillator 4 side) so as to be angularly moved. The light reflecting unit 16 is a unit that reflects the light emitted from the light projecting unit 15 at least twice and guides the light onto the scanning line of the workpiece 90. When the light projecting unit 15 operates, laser light is guided from the light reflecting unit 16 to the workpiece 90, and the irradiated point on the workpiece 90 sequentially moves in the scanning direction along the scanning line.

  In the optical scanning unit 3 according to the present embodiment, the laser light from the light projecting unit 15 is angularly moved at a substantially constant angular velocity. The laser beam on the workpiece 90 also moves on the scanning line at a substantially constant scanning speed. The optical path length from the light projecting unit 15 to an arbitrary irradiated point on the scanning line is substantially constant at all irradiated points, thereby focusing the laser beam as much as possible at the arbitrary irradiated point. The light projecting unit 15 and the light reflecting unit 16 are configured and arranged so as to realize this action (see FIG. 5).

(Projector / Reflector)
The light projecting unit 15 includes a polygon mirror 21 and a deflection actuator 22 that rotationally drives the polygon mirror 21. The polygon mirror 21 is a deflector that is rotatably supported in the housing 10, and the rotation axis of the polygon mirror 21 extends in a horizontal direction perpendicular to the scanning direction (to the ground). The deflection actuator 22 is, for example, an electric motor controlled by a controller (not shown). The deflection actuator 22 drives the polygon mirror 21 to rotate at a constant speed in one direction around the rotation axis. In addition to the polygon mirror 21, a galvanometer mirror may be applied to the deflector.

  As shown in FIG. 3, the polygon mirror 21 includes a polygon base body 23 formed in a plate shape forming a low-profile polygonal column, and a plurality of reflection deflecting units 24 provided on the side surfaces of the polygon base body 23. Have. The laser light is incident on the reflection deflection unit 24 of the rotating polygon mirror 21 and is reflected at a reflection angle corresponding to the rotation angle position of the polygon mirror 21 at that time. The arbitrary reflection deflection unit 24 forms two ridges together with each of the two adjacent reflection deflection units 24, and after the laser beam is reflected at a certain ridge of the polygon mirror 21 until it is reflected at the next ridge. The polygon mirror 21 rotates 360 / N [deg] (N: the number of reflecting portions). During this time, the laser beam continuously reflected by a certain reflecting portion of the polygon mirror 21 is deflected on the side of the polygon mirror 21 (720 / N [deg]) by the rotation angle of the polygon mirror 21 (720 / N [deg]). Move the corner around the reflection point. Although the deflection center slightly moves according to the rotation of the polygon mirror 21, the movement of the deflection center according to the rotation of the polygon mirror 21 is ignored in the following description. In other words, in this document, the entire movement range of the deflection center in a strict sense is referred to as “deflection center”.

  Returning to FIG. 2, the light reflecting unit 16 according to the present embodiment includes a primary light reflecting unit 31 that reflects the laser light from the light projecting unit 15 and secondary light that further reflects the laser light from the primary light reflecting unit 31. The laser beam from the light projecting unit 15 is reflected twice and then guided to the workpiece 90. Therefore, in the optical scanning head 5 according to the present embodiment, the laser light from the second folding mirror 14 enters the polygon mirror 21 substantially downward. The reflection deflection unit 24 of the polygon mirror 21 reflects the laser beam from the second folding mirror 14 substantially upward. The primary light reflecting portion 31 is disposed above the polygon mirror 21 and reflects the laser light from the polygon mirror 21 substantially downward. The secondary light reflecting section 32 is disposed below the primary light reflecting section 31 and reflects the laser beam from the primary light reflecting section 31 substantially upward. The laser light from the secondary light reflecting portion 32 passes through the cylindrical lens 17 and enters the second surface 90b of the workpiece 90.

  The primary light reflecting portion 31 has a plurality of flat plate-like reflecting plates 33, and the secondary light reflecting portion 32 has a plurality of flat plate-like reflecting plates 34. The plurality of reflecting plates 33 constituting the primary light reflecting portion 31 are sequentially arranged so as to be adjacent to each other, but these reflecting plates 33 may be arranged apart from each other. Although the plurality of reflecting plates 34 constituting the secondary light reflecting portion 32 are arranged apart from each other, these reflecting plates 34 may be arranged so as to be adjacent to each other in sequence.

  As described above, the laser processing apparatus 10 includes the light reflecting section 16 that bends the laser light from the light projecting section 15 twice. Therefore, as can be seen with reference to FIG. 2, when viewed in the direction in which the rotation axis of the polygon mirror 21 extends, the optical path is bent zigzag in the vertical direction. In particular, in the optical scanning unit 3 according to the present embodiment, the primary light reflecting unit 31 and the secondary light reflecting unit 32 are arranged on the opposite sides in the vertical direction with respect to the polygon mirror 21, and thus the primary light. It is necessary to dispose the light projecting unit 15 and the light reflecting unit 16 so that the optical path from the reflecting unit 31 to the secondary light reflecting unit 32 does not interfere with the polygon mirror 21. Further, it is necessary to dispose the light projecting unit 15 and the light reflecting unit 16 so that the optical path from the secondary light reflecting unit 32 to the workpiece 90 does not interfere with the polygon mirror 21 and the primary light reflecting unit 31. .

  Therefore, in the present embodiment, as shown in FIG. 4, each reflection deflector 24 of the polygon mirror 21, each reflector 33 constituting the primary light reflector 31, and each reflector 34 constituting the secondary light reflector 32 are provided. In each case, a right-angle prism 40 is applied. The right-angle prism 40 is formed in a triangular prism shape, and has three surfaces including a first boundary surface 41, a second boundary surface 42, and a hypotenuse surface 43 as side surfaces thereof. The first boundary surface 41 and the second boundary surface 42 form 90 degrees, the oblique side surface 43 and the first boundary surface 41 form 45 degrees, and the oblique side surface 43 and the second boundary surface 42 form 45 degrees. It is made. That is, the right-angle prism 40 has a cross-sectional shape of a right-angled isosceles triangle.

  The polygon main body 23 of the polygon mirror 21 has a V-shaped attachment groove 25 on each of a plurality of side surfaces. A plurality of right-angle prisms 40 are respectively fitted in a plurality of mounting grooves 25 provided in the polygon body 23 so that the hypotenuse surface 43 forms a side surface of the polygon body 23, and the first boundary surface 41 and the second boundary surface 42 is received in the mounting groove 25. The right angle prism 40 attached to the polygon main body 23 in this way functions as the reflection deflecting unit 24 of the polygon mirror 21.

  Each reflecting plate 33 constituting the primary light reflecting portion 31 and each reflecting plate 34 constituting the secondary light reflecting portion 32 have the same structure as the reflecting portion of the polygon mirror 21. The reflection plate 33 includes a block-shaped or plate-shaped main body 35, and a V-shaped attachment groove 36 is formed on one surface of the main body 35. The right-angle prism 40 is fitted into a mounting groove 36 provided in the main body 35 so that the oblique side surface 43 forms one side of the main body 35, and the first boundary surface 41 and the second boundary surface 42 are mounted in the mounting groove. 36. Each reflecting plate 34 of the secondary light reflecting portion 32 includes a main body portion 37 having a mounting groove 38, similarly to the reflecting plate 33 of the primary light reflecting portion 31, and the right-angle prism 40 is fitted in the mounting groove 38.

  In FIG. 4, the optical scanning head 5 is projected onto a plane through which the rotation axis of the polygon mirror 21 passes. When projected onto this plane, the oblique side surface 43 of the polygon mirror 21, the oblique side surface 43 of the primary light reflecting portion 31, and the oblique side surface 43 of the secondary light reflecting portion 32 are all represented as straight lines. Are arranged parallel to each other. Since the straight line representing the oblique side surface 43 in the polygon mirror 21 is parallel to the rotation axis of the polygon mirror 21, the other two straight lines are also parallel to the rotation axis of the polygon mirror 21.

  Further, the polygon mirror 21, the primary light reflecting portion 31, and the secondary light reflecting portion 32 are arranged so as to be shifted in the extending direction of the rotation axis of the polygon mirror 21. As described above, the oblique side surface 43 of the polygon mirror 21 partially overlaps with the oblique side surface of the primary light reflecting portion 31 in a plan view, while being displaced in the extending direction of the rotation axis. The oblique side surface 43 of the primary light reflecting portion 31 partially overlaps the oblique side surface 43 of the secondary light reflecting portion 32 in plan view.

  Then, the laser light from the second folding mirror 14 is incident on the oblique side surface 43 forming the reflecting portion 32 of the polygon mirror 21 along the optical path extending in the direction orthogonal to the rotation axis of the polygon mirror 21. Hereinafter, the optical path of this laser beam will be described in detail.

  In FIG. 4, since the rotation axis is shown to extend in the horizontal direction on the paper surface, the optical path incident on the polygon mirror 21 extends in the vertical direction on the paper surface. The laser light that has passed through the oblique side surface 43 is reflected by the first boundary surface 41 of the right-angle prism 40, is turned 45 degrees, and is directed to the second boundary surface 42. The laser beam from the first boundary surface 41 is reflected by the second boundary surface 42, folded back 45 degrees, and directed toward the oblique side surface 43. Laser light from the second boundary surface 42 passes through the oblique side surface 43 and is emitted from the right-angle prism 40.

  The critical angle of the right-angle prism 40 is 45 degrees or less. In order to realize such a critical angle, the right-angle prism 40 is manufactured from a glass material such as BK7 in consideration of the refractive index of air. If the critical angle of the right-angle prism 40 is 45 degrees or less, it is possible to transmit the laser beam on the oblique side surface 43 and totally reflect the laser beam on the boundary surfaces 41 and 42. Then, the energy of the laser light emitted from the right-angle prism 40 can be prevented from becoming smaller than the energy of the laser light incident on the right-angle prism 40. Since the optical scanning unit 3 according to this embodiment is applied to the laser processing apparatus 1, the energy of the laser beam is relatively large. Since such laser light can be totally reflected by the boundary surfaces 41 and 42, energy required for processing can be easily secured around the workpiece 90, and the polygon main body 23 can be damaged by the laser light. Can be prevented.

  The optical path of the laser light incident on the right-angle prism 40 is aligned in parallel with the optical path of the laser light emitted from the right-angle prism 40 when projected onto a plane through which the rotation axis of the polygon mirror 21 passes, and the rotation axis of the polygon mirror 21. Are arranged apart in the extending direction. Thus, since the incident optical path and the outgoing optical path extend in a direction orthogonal to the rotation axis and do not include a component in the extending direction of the rotation axis, the alignment work of the polygon mirror 21 and the second folding mirror 14 is very simple. Can be done.

  As described above, the laser light from the polygon mirror 21 is directed to the primary light reflecting portion 31. The oblique side surface 43 of the polygon mirror 21 and the oblique side surface 43 of the primary light reflecting portion 31 extend in parallel with the rotation axis and partially overlap when viewed in the direction orthogonal to the rotation axis. For this reason, the optical path of the laser light from the polygon mirror 21 passes through the hypotenuse surface 43 of the primary light reflecting portion 31. The laser light that has passed through the hypotenuse surface 43 of the primary light reflecting section 31 is sequentially totally reflected by the first boundary surface 41 and the second interface surface 42 in the same manner as the right angle prism 40 of the polygon mirror 21 described above, and is reflected on the hypotenuse surface 43. Pass through and exit from the right-angle prism 40.

  Then, the laser light from the primary light reflecting portion 31 is directed to the secondary light reflecting portion 32. The hypotenuse surface 43 of the primary light reflecting portion 31 and the hypotenuse surface 43 of the secondary light reflecting portion 32 extend in parallel to the rotation axis and partially overlap as seen in the direction perpendicular to the rotation axis. For this reason, the optical path of the laser light from the primary light reflecting portion 31 passes through the oblique side surface 43 of the secondary light reflecting portion 32. The laser light that has passed through the oblique side surface 43 of the secondary light reflecting portion 32 is totally totally reflected in turn by the first boundary surface 41 and the second boundary surface 42 in the same manner as the right-angle prism 40 of the secondary light reflecting portion 32 described above. The light passes through the oblique side surface 43 and exits from the right-angle prism 40.

  As described above, the outgoing optical path from the polygon mirror 21 extends in the direction orthogonal to the rotation axis along with the incident optical path to the polygon mirror 21. The outgoing optical path from the polygon mirror 21 is the same as the incident optical path to the primary light reflecting section 31. The incident optical path to the primary light reflecting portion 31 extends in a direction orthogonal to the rotation axis of the polygon mirror 21 together with the outgoing optical path from the primary light reflecting portion 31. The outgoing light path from the primary light reflecting portion 31 is the same as the incident light path to the secondary light reflecting portion 32, and the incident light path to the secondary light reflecting portion 32 is the outgoing light from the secondary light reflecting portion 32. Together with the road, it extends in a direction orthogonal to the rotational axis of the polygon mirror 21. As described above, during the period from the second folding mirror 14 to the workpiece 90, the laser light is guided in a direction perpendicular to the rotation axis of the polygon mirror 21 when entering the right-angle prism 40 and when emitting from the right-angle prism 40. In the right angle prism 40, the light is guided in the extending direction of the rotation axis of the polygon mirror 21. Thereby, the optical path between the polygon mirror 21 and the primary light reflecting portion 31 and the optical path between the primary light reflecting portion 31 and the secondary light reflecting portion 32 are in the extending direction of the rotation axis of the polygon mirror 21. The components are not included, so that the alignment work of these optical elements 21, 31, and 32 can be easily performed.

  In the same manner as described above, the energy loss of the laser light at the light reflecting portions 31 and 32 can be reduced as much as possible. Therefore, it becomes easy to secure the laser light having the intensity required for processing, and the primary light reflecting portions 31 and 2 can be secured. It is also possible to suitably prevent the base body of the secondary light reflecting portion 32 from being damaged by the laser light.

  The optical scanning unit 3 according to the present embodiment includes two light reflecting units 31 and 32, and the right angle prism 40 is applied to a total of three optical elements including the polygon mirror 21, but at least one of them is used. The right-angle prism 40 may be applied to. Note that, as in the present embodiment, by applying the right-angle prism 40 to all of the elements that reflect the laser light, the alignment operation of the entire optical scanning unit 3 can be performed remarkably easily. In other words, when there are a plurality of light reflecting portions as in the present embodiment, the operational effects obtained by applying the right angle prism become remarkable.

(Operation of the light reflection part)
Finally, the effects obtained when the optical scanning unit according to the present embodiment has two or more light reflecting units will be briefly described. In the above embodiment, there is no special means for changing the focal length of the laser light in accordance with the rotation angle of the polygon mirror 21. If there is no light reflecting portion, the focal point of the laser light draws an arc-shaped locus. The center of the locus becomes the deflection center, and the radius of the locus is the optical path length from the deflection center to the focal point. On the other hand, the scanning line on the work 90 extends linearly in the scanning direction, unlike an arc-shaped locus. Then, the distance from the arbitrary irradiated point on the scanning line to the focal point changes depending on the position of the irradiated point (that is, the deflection angle of the laser beam and the rotation angle of the polygon mirror 21). Therefore, the optical path length from the polygon mirror 21 to an arbitrary irradiated point on the scanning line is not constant over the entire irradiated point, and changes according to the position of the irradiated point. If the laser beam is angularly moved at a constant speed, the scanning speed of the laser beam on the scanning line is not constant. Therefore, in the optical scanning unit 3 according to the present embodiment, the light reflecting unit 16 is configured to reflect the laser light from the light projecting unit 15 at least twice and then guide it to the workpiece 90 in order to solve this problem. The

  FIG. 5 illustrates a case where the laser light moves in the scanning direction by the workpiece 90 along one scanning line while the laser light passes through one reflecting surface of the polygon mirror 21. If the primary light reflection part 31 and the secondary light reflection part 32 do not exist, the focal point of the laser light will draw an arc centered on the deflection center C. Since the radius of the virtual arc VA is the optical path length from the deflection center C to the focal point, the primary light reflecting unit 31 and the secondary light reflecting unit 32 bend the optical path from the deflection center C to the focal point, and thereby the virtual arc VA. Are rearranged so as to extend linearly on the workpiece 90 in the scanning direction. In order to change the position of the virtual arc VA in this way, the length of the virtual arc VA is required to be equal to the line length required for processing (required scanning line length).

  When the number of reflection surfaces of the polygon mirror 21 is N, the central angle of the virtual arc VA is 720 / π [deg]. When the circumference ratio is π and the radius of the virtual arc VA is R, the length of the virtual arc VA is 2πR / [360 × (N / 720)], which is equal to the necessary line length described above. On the other hand, geometrically, the required line length cannot be longer than the diameter of the virtual arc VA. From the inequalities derived from these relationships, the number of reflecting surfaces N is required to be smaller than the diameter (2R) of the virtual arc, and therefore the polygon mirror 21 preferably has seven or more reflecting surfaces.

  The methodology for rearranging the virtual arc VA so as to match the scanning line will be described. First, a plurality of virtual divided arcs DVA1, DVA2,... Are divided by dividing the virtual arc VA at equal intervals. A plurality of virtual strings VC1, VC2,. Then, the plurality of virtual divided arcs DVA1, DVA2,... Are rearranged so that the plurality of virtual strings VC1, VC2,. Thus, a scanning line is formed by the plurality of virtual strings VC1 ′, VC2 ′,.

  When the scanning line is formed in this way, two ends of the virtual divided arc DVA are rearranged on the scanning line, and the virtual divided arcs DVA1 ′, DVA2 ′,... (That is, a curve connecting the two points) Rearrangement is performed downstream of the scanning line in the optical path direction (upper side in the laser processing apparatus 1 according to the present embodiment). The focal point tends to move along the virtual divided arcs DVA1 ′, DVA2 ′,. The virtual divided arcs DVA1 ′, DVA2 ′,... After the rearrangement are sequentially continued in the scanning direction in the same manner as the virtual strings VC1 ′, VC2 ′,.

  When the virtual arc VA is divided to obtain a plurality of virtual divided arcs DVA1, DVA2,..., The virtual divided arcs DVA1, DVA2, ... are well approximated to the corresponding virtual chords VC1, VC2,. Therefore, the optical path length from the deflection center C of the polygon mirror 21 to an arbitrary irradiated point on the scanning line is substantially constant over all the focal points. If the laser beam is angularly moved at a constant speed, the focal point tends to move at a constant speed along the virtual divided arcs DVA1 ′, DVA2 ′,. Since the virtual divided arcs DVA1 ′, DVA2 ′,... After the rearrangement are well approximated with the corresponding virtual strings VC1 ′, VC2 ′,... After the rearrangement, the behavior of the focus is along the scanning line, etc. Good approximation to fast linear movement.

  As described above, if it is assumed that the light reflecting portion 16 does not exist, the focal point of the laser light emitted from the light projecting portion 16 draws a virtual arc VA with the deflection center C as the center. A plurality of virtual divided arcs DVA1, DVA2,... Obtained by dividing the virtual arc VA by reflecting them twice, and a plurality of virtual strings VC1, VC2,. The laser light guided to the workpiece 90 is scanned along a scanning line formed by a plurality of virtual strings VC1 ′, VC2 ′,. This makes it possible to keep the laser beam focused on the workpiece 90 as much as possible while rotating the deflection actuator 22 and the polygon mirror 21 at a constant speed to simplify these operations. It can also be moved to. Therefore, it is possible to simultaneously improve the operation reliability of the optical scanning unit 3, improve the processing efficiency, and suppress the processing unevenness. In addition, it is not necessary to use special means for changing the focal length of the laser light according to the rotation angle of the polygon mirror 21. The distance between the midpoint of the virtual chord and the midpoint of the virtual split arc increases as the number of divisions of the virtual split arc DVA1, DVA2,... Increases (the center angle of the virtual split arc decreases). Becomes smaller and the focal point approaches the virtual string. For this reason, the optical path length is kept constant, and the constant velocity of the laser light is also kept high. The number of divisions can be appropriately determined according to the error required for the optical scanning unit 3 and the laser processing apparatus 1.

  A more specific methodology for virtual string rearrangement will be described. In order to change the position of the virtual string on the workpiece 90, for example, a sector formed by a virtual divided arc corresponding to the virtual string may be bent at least twice. In the present embodiment, since the light reflecting portion has two light reflecting portions, that is, a primary light reflecting portion and a secondary light reflecting portion, the sector shape is bent twice. Thus, for example, when a sector is bent twice, two folds are formed into a sector. Of these, the first fold corresponds to one of the plurality of reflecting portions constituting the primary light reflecting portion, and the second fold corresponds to one of the plurality of reflecting portions constituting the secondary light reflecting portion. To do. That is, as described above, the primary light reflecting portion has a plurality of plate-like reflecting portions, and the number of the reflecting portions is equal to the number of divisions of the virtual divided arc. Note that a plurality of virtual strings cannot be rearranged along a straight line unless the sector is bent twice or more. For this reason, the light reflecting portion 16 has a plurality of reflecting portions.

  In order to make the virtual strings continue successively, it is preferable that adjacent first fan-shaped folds do not overlap each other. That is, it is preferable that the reflecting portion of the primary light reflecting portion corresponding to a certain virtual divided arc does not overlap the reflecting surface of the primary light reflecting portion corresponding to the virtual divided arc adjacent thereto. If it carries out like this, the 2nd crease | fold can be arranged in the up-down direction with the virtual string after the rearrangement corresponding to this. Thereby, the laser beam reflected by the secondary light reflecting portion can be incident on the workpiece 90 substantially vertically. Thereby, processing efficiency is further improved and processing unevenness can be further suppressed. In addition, if the ends of the adjacent first fan-shaped folds are continuous, it is beneficial because the entire primary light reflecting portion can be made as small as possible.

  Even when three or more light reflecting portions are present, the same effect as described above can be obtained. Also at this time, a right-angle prism can be applied to the reflecting surface of each light reflecting portion. By applying the right-angle prism 40 to all the light reflecting portions, the time and labor required for the alignment work of the light scanning portion 3 can be greatly reduced. Thus, in the optical scanning unit 3 according to the present embodiment, the operation of the light projecting unit 15 is simplified, the laser beam is moved at a constant speed on the scanning line, and the scanning line is scanned as much as possible during the scanning. The laser beam emitted from the light projecting unit 15 is bent twice or more in order to achieve the simultaneous focusing of the laser beam and the continuous focusing of the laser beam as much as possible. . If all the right-angle prisms 40 of the optical scanning unit 3 are applied, the optical path can be prevented from interfering with other optical elements even if the optical path is bent in a complicated manner. The entire 3 alignment operations can be easily performed, which is beneficial. As described above, the present invention is useful when applied to an optical scanning device including a plurality of light reflecting units 16, but is not limited to the optical scanning unit 3 having the above-described configuration, and various configurations (for example, a light reflecting unit may be used). The present invention can also be suitably applied to an optical scanning device having a structure with only one).

  In providing an optical scanning device and a laser processing apparatus including the optical scanning device, the present invention has a remarkable effect that an optical device constituting the optical scanning device can be easily and highly accurately arranged. It is useful when applied to an optical scanning device configured to reflect a plurality of times and guide it to an irradiation point of a scanning line and a laser processing apparatus including the same.

DESCRIPTION OF SYMBOLS 1 Laser processing apparatus 3 Optical scanning part 5 Optical scanning head 14 Second folding mirror 15 Light projection part 16 Light reflection part 21 Polygon mirror 22 Deflection actuator 24 Reflection deflection part 31 Primary light reflection part 32 Secondary light reflection parts 33 and 34 Reflection Plate 40 Right angle prism 41 First boundary surface 42 Second boundary surface 43 Oblique side surface

Claims (4)

A light projecting unit that emits light while angularly moving, and one or more reflecting units that reflect the light emitted from the light projecting unit and guide the light onto a predetermined scanning line,
The light projecting unit includes a reflection deflecting unit that reflects and deflects light, and includes a deflector that emits light while rotating the light from the reflection deflecting unit by rotation.
The reflective deflecting portion and the one or more reflective portions of the deflector each include a right-angle prism having a hypotenuse surface, a first boundary surface, and a second boundary surface;
The oblique side surface of the reflection deflection unit and the oblique side surface of the reflection unit are arranged perpendicular to a plane perpendicular to the rotation axis of the angular movement of light in the light projecting unit, and the angular movement of light in the light projecting unit. Are arranged so as to partially overlap each other in the direction of the optical axis, and are arranged so as to be partially offset when viewed in the optical path direction between the oblique sides adjacent to each other in the extending direction.
The incident light path to the right-angle prism and the output light path from the right-angle prism do not include the component in the extending direction, while the light incident on the right-angle prism passes through the oblique side surface and the first boundary surface. in reflected and proceeds in parallel with the extending direction within the rectangular prism, is reflected by the second boundary surface through the hypotenuse surface, it is emitted from the rectangular prism, the optical scanning device. Wherein said hypotenuse surface first boundary surface and the angle formed, the hypotenuse surface and the second boundary surface and the angle formed is 45 degrees, an optical scanning device according to claim 1. The optical scanning device according to claim 2 , wherein a critical angle of the right-angle prism is 45 degrees or less. It includes the optical scanning apparatus according to any one of claims 1 to 3, to form a groove along the scan line on the workpiece by machining a workpiece with laser light from the optical scanning device, the laser processing apparatus.

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