Variable light beam shaper and laser processing device

Abstract

This variable light beam shaper comprises a diffractive optical system. The diffractive optical system includes a first diffractive optical element and a second diffractive optical element. The diffractive optical system generates a center spot beam from a first beam and generates a ring beam around the center spot beam from a second beam. One of the first diffractive optical element and the second diffractive optical element is configured to be rotatable about the optical axis of the diffractive optical system with respect to the other one of the first diffractive optical element and the second diffractive optical element. The first diffractive optical element and the second diffractive optical element are a first spiral axicon diffractive optical element and a second spiral axicon diffractive optical element, or are a first spiral diffractive optical element and a second spiral diffractive optical element each having a periodic phase distribution in the radial direction.

Description

Variable optical beam shaper and laser processing device

[0001] The present disclosure relates to a variable optical beam shaper and a laser processing device. This application claims priority to an international application (PCT / JP2024 / 015443) filed on April 18, 2024, the entire contents of which are incorporated herein by reference.

[0002] International Publication No. 2018 / 159857 (Patent Document 1) discloses a laser welding apparatus including a laser oscillator and an optical head. The optical head includes a diffractive optical element as a beam shaper. The optical head generates a main beam and ring-shaped sub-beams around the main beam on a workpiece from a laser beam output from the laser oscillator. The power density of the sub-beams is lower than that of the main beam.

[0003] International Publication No. 2018 / 159857

[0004] The variable optical beam shaper disclosed herein comprises a diffractive optical system. The diffractive optical system includes a first diffractive optical element and a second diffractive optical element. The first diffractive optical element and the second diffractive optical element can generate a first beam and a second beam having different diffraction orders from a laser beam incident on the diffractive optical system. The diffractive optical system can generate a central spot beam and a ring beam around the central spot beam from the first beam and the second beam, respectively. One of the first diffractive optical element and the second diffractive optical element is configured to be rotatable about the optical axis of the diffractive optical system relative to the other of the first diffractive optical element and the second diffractive optical element. The first diffractive optical element and the second diffractive optical element are a first spiral axicon diffractive optical element and a second spiral axicon diffractive optical element, respectively, or a first spiral diffractive optical element and a second spiral diffractive optical element, each having a periodic phase distribution in the radial direction. The periodic phase distribution is symmetric within one period of the periodic phase distribution. In the periodic phase distribution, the phase changes stepwise in the radial direction by a number of steps greater than two, or the phase changes continuously in the radial direction.

[0005] Fig. 1 is a schematic diagram of a laser processing apparatus according to Embodiments 1 to 3. Fig. 2 is a schematic diagram of a central spot beam and a ring beam generated by a variable optical beam shaper according to Embodiments 1 to 5. Fig. 3 is a diagram showing the phase distribution of a first spiral axicon diffractive optical element and the phase distribution of a second spiral axicon diffractive optical element in Example 1, which is an example of Example 1. Fig. 4A is a diagram showing the phase distribution of a composite phase when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degrees in Example 1. Fig. 4B is a diagram showing the intensity distribution of a laser beam generated by a variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degrees in Example 1. Figure 4C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degrees in the first embodiment. Figure 5A is a diagram showing the phase distribution of a composite phase when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 80 degrees in the first embodiment. Figure 5B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 80 degrees in the first embodiment. Figure 5C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 80 degrees in the first embodiment. 6A and 6B are diagrams illustrating a phase distribution of a composite phase when the relative angle between the first and second spiral axicon diffractive optical elements is 85 degrees in the first embodiment, and an intensity distribution of a laser beam generated by the variable optical beam shaper when the relative angle between the first and second spiral axicon diffractive optical elements is 85 degrees in the first embodiment.Figure 6C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 85 degrees in the first embodiment. Figure 7A is a diagram showing the phase distribution of a composite phase when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 90 degrees in the first embodiment. Figure 7B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 90 degrees in the first embodiment. Figure 7C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 90 degrees in the first embodiment. Figure 8A is a diagram showing a portion of the phase distribution of the first spiral axicon diffractive optical element in the x direction when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degrees in the first embodiment. Figure 8B is a diagram showing a portion of the phase distribution of the second spiral axicon diffractive optical element in the x direction when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degrees in the first embodiment. Figure 8C is a diagram showing a portion of the phase distribution of the composite phase in the x direction when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degrees in the first embodiment. Figure 9A is a diagram showing a portion of the phase distribution of the first spiral axicon diffractive optical element in the x direction when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 90 degrees in the first embodiment. FIG. 9B is a diagram showing a part of the phase distribution of the second spiral axicon diffractive optical element in the x direction when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 90 degrees in the first embodiment.Fig. 9C is a diagram showing a portion of the phase distribution of the composite phase in the x direction when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 90 degrees in Example 1. Fig. 10 is a diagram showing the phase distribution of the first spiral axicon diffractive optical element and the phase distribution of the second spiral axicon diffractive optical element in Example 2, which is an example of Embodiment 1. Fig. 11A is a diagram showing the phase distribution of the composite phase when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degrees in Example 2. Fig. 11B is a diagram showing the intensity distribution of the laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degrees in Example 2. Figure 11C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degrees in the second embodiment. Figure 12A is a diagram showing the phase distribution of a composite phase when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 30 degrees in the second embodiment. Figure 12B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 30 degrees in the second embodiment. Figure 12C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 30 degrees in the second embodiment. FIG. 13A is a diagram showing the phase distribution of the composite phase when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 60 degrees in the second embodiment.Figure 13B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper in the second embodiment when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 60 degrees. Figure 13C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper in the second embodiment when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 60 degrees. Figure 14A is a diagram showing the phase distribution of a composite phase in the second embodiment when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 180 degrees. Figure 14B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper in the second embodiment when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 180 degrees. Figure 14C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 180 degrees in the second embodiment. Figure 15A is a diagram showing a portion of the phase distribution of the first spiral axicon diffractive optical element in the x direction when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degrees in the second embodiment. Figure 15B is a diagram showing a portion of the phase distribution of the second spiral axicon diffractive optical element in the x direction when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degrees in the second embodiment. Figure 15C is a diagram showing a portion of the phase distribution of the composite phase in the x direction when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degrees in the second embodiment. FIG. 16A is a diagram showing a part of the phase distribution of the first spiral axicon diffractive optical element in the x direction when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 180 degrees in the second embodiment.Fig. 16B is a diagram showing a portion of the phase distribution of the second spiral axicon diffractive optical element in the x direction when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 180 degrees in Example 2. Fig. 16C is a diagram showing a portion of the phase distribution of the composite phase in the x direction when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 180 degrees in Example 2. Fig. 17 is a diagram showing the phase distribution of the first spiral axicon diffractive optical element of Example 3, which is an example of Embodiment 1. Fig. 18 is a diagram showing the phase distribution of the second spiral axicon diffractive optical element of Example 3. Fig. 19A is a diagram showing the phase distribution of the composite phase when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degrees in Example 3. Figure 19B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper in the third embodiment when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degrees. Figure 19C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper in the third embodiment when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degrees. Figure 20A is a diagram showing the phase distribution of a composite phase in the third embodiment when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 80 degrees. Figure 20B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper in the third embodiment when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 80 degrees. FIG. 20C is a diagram showing the intensity distribution in the x-direction of the laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 80 degrees in the third embodiment.Figure 21A is a diagram showing the phase distribution of a composite phase when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 85 degrees in the third embodiment. Figure 21B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 85 degrees in the third embodiment. Figure 21C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 85 degrees in the third embodiment. Figure 22A is a diagram showing the phase distribution of a composite phase when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 90 degrees in the third embodiment. Figure 22B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper in the third embodiment when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 90 degrees. Figure 22C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper in the third embodiment when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 90 degrees. Figure 23A is a diagram showing a portion of the phase distribution of the first spiral axicon diffractive optical element in the x direction when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degrees in the third embodiment. Figure 23B is a diagram showing a portion of the phase distribution of the second spiral axicon diffractive optical element in the x direction when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degrees in the third embodiment. FIG. 23C is a diagram showing a part of the phase distribution of the composite phase in the x direction when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degree in the third example.Figure 24A is a diagram showing a portion of the phase distribution of the first spiral axicon diffractive optical element in the x direction when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 90 degrees in the third embodiment. Figure 24B is a diagram showing a portion of the phase distribution of the second spiral axicon diffractive optical element in the x direction when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 90 degrees in the third embodiment. Figure 24C is a diagram showing a portion of the phase distribution of the composite phase in the x direction when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 90 degrees in the third embodiment. Figure 24D is a diagram showing a portion of the phase distribution of the first spiral phase component of the composite phase in the x direction when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 90 degrees in the third embodiment. Fig. 24E is a diagram showing a part of the phase distribution of the second spiral phase component of the composite phase in the x direction when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 90 degrees in Example 3. Fig. 25 is a diagram showing the phase distribution of the first spiral axicon diffractive optical element and the phase distribution of the second spiral axicon diffractive optical element in Example 4, which is an example of Embodiment 1. Fig. 26A is a diagram showing the phase distribution of the composite phase when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degrees in Example 4. Fig. 26B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degrees in Example 4. FIG. 26C is a diagram showing the intensity distribution in the x-direction of the laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degree in the fourth example.Figure 27A is a diagram showing the phase distribution of the composite phase when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 2 degrees in the fourth embodiment. Figure 27B is a diagram showing the intensity distribution of the laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 2 degrees in the fourth embodiment. Figure 27C is a diagram showing the intensity distribution in the x direction of the laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 2 degrees in the fourth embodiment. Figure 28A is a diagram showing the phase distribution of the composite phase when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 4 degrees in the fourth embodiment. Figure 28B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper in the fourth embodiment when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 4 degrees. Figure 28C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper in the fourth embodiment when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 4 degrees. Figure 29A is a diagram showing the phase distribution of a composite phase in the fourth embodiment when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 18 degrees. Figure 29B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper in the fourth embodiment when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 18 degrees. FIG. 29C is a diagram showing the intensity distribution in the x-direction of the laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 18 degrees in the fourth example.

[0046] Figure 30A is a diagram showing the phase distribution of a composite phase when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 36 degrees in Example 4. Figure 30B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 36 degrees in Example 4. Figure 30C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element in Example 4. Figure 31 is a diagram showing the phase distribution of the first spiral axicon diffractive optical element and the phase distribution of the second spiral axicon diffractive optical element in Example 5, which is an example of Embodiment 1. Figure 32A is a diagram showing the phase distribution of the composite phase when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degrees in the fifth embodiment. Figure 32B is a diagram showing the intensity distribution of the laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degrees in the fifth embodiment. Figure 32C is a diagram showing the intensity distribution in the x direction of the laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degrees in the fifth embodiment. Figure 33A is a diagram showing the phase distribution of the composite phase when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 1 degree in the fifth embodiment. FIG. 33B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper in the fifth embodiment when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 1 degree.Figure 33C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper in the fifth embodiment when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 1 degree. Figure 34A is a diagram showing the phase distribution of a composite phase in the fifth embodiment when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 2 degrees. Figure 34B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper in the fifth embodiment when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 2 degrees. Figure 34C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper in the fifth embodiment when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 2 degrees. Figure 35A is a diagram showing the phase distribution of the composite phase when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 9 degrees in the fifth embodiment. Figure 35B is a diagram showing the intensity distribution of the laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 9 degrees in the fifth embodiment. Figure 35C is a diagram showing the intensity distribution in the x direction of the laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 9 degrees in the fifth embodiment. Figure 36A is a diagram showing the phase distribution of the composite phase when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 18 degrees in the fifth embodiment. FIG. 36B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper in the fifth example when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 18 degrees.Fig. 36C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 18 degrees in Example 5. Fig. 37 is a diagram showing the phase distribution of the first spiral axicon diffractive optical element and the phase distribution of the second spiral axicon diffractive optical element in Example 6, which is an example of Embodiment 2. Fig. 38 is a diagram showing a part of the phase distribution of the first spiral axicon diffractive optical element in the x direction and a part of the phase distribution of the second spiral axicon diffractive optical element in the x direction when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degrees in Example 6. Fig. 39A is a diagram showing the phase distribution of a composite phase when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degrees in Example 6. Figure 39B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper in the sixth embodiment when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degrees. Figure 39C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper in the sixth embodiment when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degrees. Figure 40A is a diagram showing the phase distribution of a composite phase in the sixth embodiment when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 10 degrees. Figure 40B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper in the sixth embodiment when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 10 degrees. FIG. 40C is a diagram showing the intensity distribution in the x-direction of the laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 10 degrees in the sixth example.Figure 41A is a diagram showing the phase distribution of a composite phase when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 20 degrees in the sixth embodiment. Figure 41B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 20 degrees in the sixth embodiment. Figure 41C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 20 degrees in the sixth embodiment. Figure 42A is a diagram showing the phase distribution of a composite phase when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 30 degrees in the sixth embodiment. Figure 42B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper in the sixth embodiment when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 30 degrees. Figure 42C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper in the sixth embodiment when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 30 degrees. Figure 43A is a diagram showing the phase distribution of a composite phase in the sixth embodiment when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 80 degrees. Figure 43B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper in the sixth embodiment when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 80 degrees. FIG. 43C is a diagram showing the intensity distribution in the x-direction of the laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 80 degrees in the sixth example.Figure 44A is a diagram showing the phase distribution of a composite phase when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 90 degrees in Example 6. Figure 44B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 90 degrees in Example 6. Figure 44C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element in Example 6. Figure 45 is a diagram showing the phase distribution of the first spiral axicon diffractive optical element and the phase distribution of the second spiral axicon diffractive optical element in Example 7, which is an example of Embodiment 3. Figure 46A is a diagram showing the phase distribution of the composite phase when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degrees in the seventh embodiment. Figure 46B is a diagram showing the intensity distribution of the laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degrees in the seventh embodiment. Figure 46C is a diagram showing the intensity distribution in the x direction of the laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degrees in the seventh embodiment. Figure 47A is a diagram showing the phase distribution of the composite phase when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 10 degrees in the seventh embodiment. FIG. 47B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper in the seventh embodiment when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 10 degrees.Figure 47C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper in the seventh embodiment when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 10 degrees. Figure 48A is a diagram showing the phase distribution of a composite phase in the seventh embodiment when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 20 degrees. Figure 48B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper in the seventh embodiment when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 20 degrees. Figure 48C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper in the seventh embodiment when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 20 degrees. Figure 49A is a diagram showing the phase distribution of a composite phase when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 80 degrees in the seventh embodiment. Figure 49B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 80 degrees in the seventh embodiment. Figure 49C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 80 degrees in the seventh embodiment. Figure 50A is a diagram showing the phase distribution of a composite phase when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 90 degrees in the seventh embodiment. FIG. 50B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper in the seventh embodiment when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 90 degrees.Figure 50C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 90 degrees in the seventh embodiment. Figure 51A is a diagram showing a portion of the phase distribution of the first spiral axicon diffractive optical element in the x direction when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degrees in the seventh embodiment. Figure 51B is a diagram showing a portion of the phase distribution of the second spiral axicon diffractive optical element in the x direction when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degrees in the seventh embodiment. Figure 51C is a diagram showing a portion of the phase distribution of the composite phase in the x direction when the relative angle between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 degrees in the seventh embodiment. Fig. 52 is a diagram showing the phase distribution of the first spiral diffractive optical element and the phase distribution of the second spiral diffractive optical element in Example 8, which is an example of Embodiment 4. Fig. 53 is a diagram showing a part of the phase distribution of the first spiral diffractive optical element in the x direction and a part of the phase distribution of the second spiral diffractive optical element in the x direction when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 0 degrees in Example 8. Fig. 54A is a diagram showing the phase distribution of the composite phase when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 0 degrees in Example 8. Fig. 54B is a diagram showing the intensity distribution of the laser beam generated by the variable optical beam shaper when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 0 degrees in Example 8. Figure 54C shows the intensity distribution in the x-direction of the laser beam generated by the variable optical beam shaper when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 0 degrees in the eighth embodiment.Figure 55A is a diagram showing the phase distribution of the composite phase when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 45 degrees in the eighth embodiment. Figure 55B is a diagram showing the intensity distribution of the laser beam generated by the variable optical beam shaper when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 45 degrees in the eighth embodiment. Figure 55C is a diagram showing the intensity distribution in the x direction of the laser beam generated by the variable optical beam shaper when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 45 degrees in the eighth embodiment. Figure 56A is a diagram showing the phase distribution of the composite phase when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 60 degrees in the eighth embodiment. Figure 56B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper in the eighth embodiment when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 60 degrees. Figure 56C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper in the eighth embodiment when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 60 degrees. Figure 57A is a diagram showing the phase distribution of a composite phase in the eighth embodiment when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 180 degrees. Figure 57B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper in the eighth embodiment when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 180 degrees. Fig. 57C is a diagram showing the intensity distribution in the x direction of the laser beam generated by the variable optical beam shaper when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 180 degrees in Example 8. Fig. 58 is a diagram showing the phase distribution of the first spiral diffractive optical element and the phase distribution of the second spiral diffractive optical element in Example 9, which is an example of Embodiment 4.Figure 59 is a diagram showing a portion of the phase distribution of the first spiral diffractive optical element in the x direction and a portion of the phase distribution of the second spiral diffractive optical element in the x direction when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 0 degrees in Examples 9 and 10. Figure 60A is a diagram showing the phase distribution of the composite phase when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 0 degrees in Example 9. Figure 60B is a diagram showing the intensity distribution of the laser beam generated by the variable optical beam shaper when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 0 degrees in Example 9. Figure 60C is a diagram showing the intensity distribution in the x direction of the laser beam generated by the variable optical beam shaper when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 0 degrees in Example 9. Figure 61A is a diagram showing the phase distribution of the composite phase when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 30 degrees in the ninth embodiment. Figure 61B is a diagram showing the intensity distribution of the laser beam generated by the variable optical beam shaper when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 30 degrees in the ninth embodiment. Figure 61C is a diagram showing the intensity distribution in the x direction of the laser beam generated by the variable optical beam shaper when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 30 degrees in the ninth embodiment. Figure 62A is a diagram showing the phase distribution of the composite phase when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 50 degrees in the ninth embodiment. Figure 62B is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 50 degrees in Example 9. Figure 62C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 50 degrees in Example 9.Figure 63A is a diagram showing the phase distribution of a composite phase when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 180 degrees in Example 9. Figure 63B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 180 degrees in Example 9. Figure 63C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 180 degrees in Example 9. Figure 64 is a diagram showing the phase distribution of a first spiral diffractive optical element and a second spiral diffractive optical element in Example 10, which is an example of Embodiment 4. Figure 65A is a diagram showing the phase distribution of a composite phase when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 0 degrees in Example 10. Figure 65B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper in the tenth example when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 0 degrees. Figure 65C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper in the tenth example when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 0 degrees. Figure 66A is a diagram showing the phase distribution of a composite phase in the tenth example when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 10 degrees. Figure 66B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper in the tenth example when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 10 degrees. Figure 66C shows the intensity distribution in the x-direction of the laser beam generated by the variable optical beam shaper when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 10 degrees in the tenth embodiment.Figure 67A is a diagram showing the phase distribution of the composite phase when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 17 degrees in Example 10. Figure 67B is a diagram showing the intensity distribution of the laser beam generated by the variable optical beam shaper when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 17 degrees in Example 10. Figure 67C is a diagram showing the intensity distribution in the x direction of the laser beam generated by the variable optical beam shaper when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 17 degrees in Example 10. Figure 68A is a diagram showing the phase distribution of the composite phase when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 60 degrees in Example 10. Figure 68B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 60 degrees in Example 10. Figure 68C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 60 degrees in Example 10. Figure 69 is a diagram showing the phase distribution of the first spiral diffractive optical element and the phase distribution of the second spiral diffractive optical element in Example 11, which is an example of Embodiment 4. Figure 70 is a diagram showing a portion of the phase distribution of the first spiral diffractive optical element in the x direction and a portion of the phase distribution of the second spiral diffractive optical element in the x direction when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 0 degrees in Example 11. Figure 71A is a diagram showing the phase distribution of the composite phase when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 0 degrees in Example 11. Figure 71B is a diagram showing the intensity distribution of the laser beam generated by the variable optical beam shaper when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 0 degrees in Example 11.Figure 71C is a diagram showing the intensity distribution in the x direction of a laser beam generated by a variable optical beam shaper when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 0 degrees in Example 11. Figure 72A is a diagram showing the phase distribution of a composite phase when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 30 degrees in Example 11. Figure 72B is a diagram showing the intensity distribution of a laser beam generated by a variable optical beam shaper when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 30 degrees in Example 11. Figure 72C is a diagram showing the intensity distribution in the x direction of a laser beam generated by a variable optical beam shaper when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 30 degrees in Example 11. Figure 73A is a diagram showing the phase distribution of the composite phase when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 50 degrees in Example 11. Figure 73B is a diagram showing the intensity distribution of the laser beam generated by the variable optical beam shaper when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 50 degrees in Example 11. Figure 73C is a diagram showing the intensity distribution in the x direction of the laser beam generated by the variable optical beam shaper when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 50 degrees in Example 11. Figure 74A is a diagram showing the phase distribution of the composite phase when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 180 degrees in Example 11. Figure 74B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 180 degrees in Example 11. Figure 74C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper when the relative angle between the first spiral diffractive optical element and the second spiral diffractive optical element is 180 degrees in Example 11.Fig. 75 is a schematic diagram of the laser processing apparatus of Embodiment 5. Fig. 76 is a diagram showing the phase distribution of the first spiral axicon diffractive optical element and the phase distribution of the second spiral axicon diffractive optical element of Example 12, which is an example of Example 5. Fig. 77A is a diagram showing the phase distribution of the laser beam immediately after passing through the second spiral axicon diffractive optical element when the relative distance between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 mm in Example 12. Fig. 77B is a diagram showing the intensity distribution of the laser beam generated by the variable optical beam shaper when the relative distance between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 mm in Example 12. Fig. 77C is a diagram showing the intensity distribution in the x direction of the laser beam generated by the variable optical beam shaper when the relative distance between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 0 mm in Example 12. Figure 78A is a diagram showing the phase distribution of a laser beam immediately after passing through the second spiral axicon diffractive optical element when the relative distance between the first and second spiral axicon diffractive optical elements is 5 mm in Example 12. Figure 78B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper when the relative distance between the first and second spiral axicon diffractive optical elements is 5 mm in Example 12. Figure 78C is a diagram showing the intensity distribution in the x-direction of a laser beam generated by the variable optical beam shaper when the relative distance between the first and second spiral axicon diffractive optical elements is 5 mm in Example 12. FIG. 79A is a diagram showing the phase distribution of a laser beam immediately after passing through the second spiral axicon diffractive optical element in the twelfth example, when the relative distance between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 20 mm.Figure 79B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper in the twelfth embodiment when the relative distance between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 20 mm. Figure 79C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper in the twelfth embodiment when the relative distance between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 20 mm. Figure 80A is a diagram showing the phase distribution of a laser beam immediately after passing through the second spiral axicon diffractive optical element in the twelfth embodiment when the relative distance between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 100 mm. Figure 80B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper in the twelfth example when the relative distance between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 100 mm. Figure 80C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper in the twelfth example when the relative distance between the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element is 100 mm. Figure 81 is a diagram showing the phase distribution of the first axicon diffractive optical element and the phase distribution of the second axicon diffractive optical element in a thirteenth example which is an example of Embodiment 5. Figure 82A is a diagram showing the phase distribution of a laser beam immediately after passing through the second axicon diffractive optical element in the thirteenth example when the relative distance between the first axicon diffractive optical element and the second axicon diffractive optical element is 0 mm. Figure 82B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper when the relative distance between the first axicon diffractive optical element and the second axicon diffractive optical element is 0 mm in Example 13. Figure 82C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper when the relative distance between the first axicon diffractive optical element and the second axicon diffractive optical element is 0 mm in Example 13.Figure 83A is a diagram showing the phase distribution of a laser beam immediately after passing through the second axicon diffractive optical element when the relative distance between the first axicon diffractive optical element and the second axicon diffractive optical element is 5 mm in the thirteenth embodiment. Figure 83B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper when the relative distance between the first axicon diffractive optical element and the second axicon diffractive optical element is 5 mm in the thirteenth embodiment. Figure 83C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper when the relative distance between the first axicon diffractive optical element and the second axicon diffractive optical element is 5 mm in the thirteenth embodiment. Figure 84A is a diagram showing the phase distribution of a laser beam immediately after passing through the second axicon diffractive optical element when the relative distance between the first axicon diffractive optical element and the second axicon diffractive optical element is 20 mm in the thirteenth embodiment. Figure 84B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper in the thirteenth embodiment when the relative distance between the first axicon diffractive optical element and the second axicon diffractive optical element is 20 mm. Figure 84C is a diagram showing the intensity distribution in the x direction of a laser beam generated by the variable optical beam shaper in the thirteenth embodiment when the relative distance between the first axicon diffractive optical element and the second axicon diffractive optical element is 20 mm. Figure 85A is a diagram showing the phase distribution of a laser beam immediately after passing through the second axicon diffractive optical element in the thirteenth embodiment when the relative distance between the first axicon diffractive optical element and the second axicon diffractive optical element is 100 mm. Figure 85B is a diagram showing the intensity distribution of a laser beam generated by the variable optical beam shaper in the thirteenth embodiment when the relative distance between the first axicon diffractive optical element and the second axicon diffractive optical element is 100 mm. Fig. 85C is a diagram showing the intensity distribution in the x direction of the laser beam generated by the variable optical beam shaper when the relative distance between the first axicon diffractive optical element and the second axicon diffractive optical element is 100 mm in Example 13. Fig. 86 is a schematic diagram of the laser processing apparatus of Example 6.Fig. 87 is a schematic diagram of a central spot beam and a ring beam generated by the variable optical beam shaper of embodiment 6. Fig. 88 is a schematic diagram of a first variable magnification optical system included in the variable optical beam shapers of embodiments 6 and 7. Fig. 89 is a schematic diagram of a laser processing apparatus of embodiment 7. Fig. 90 is a schematic diagram of a central spot beam and a ring beam generated by the variable optical beam shaper of embodiment 7. Fig. 91 is a schematic diagram of a second variable magnification optical system included in the variable optical beam shaper of embodiment 7.

[0006] [Problem to be Solved by the Present Disclosure] However, in Patent Document 1, it is not possible to change the ratio between the intensity of the main beam and the intensity of the ring-shaped side beam. The present disclosure has been made in consideration of the above problem, and has an object to provide a variable optical beam shaper and a laser processing apparatus that can change the ratio between a first intensity of a central spot beam and a second intensity of a ring beam surrounding the central spot beam.

[0007] Effect of the Present Disclosure According to the present disclosure, it is possible to change the ratio between the first intensity of the central spot beam and the second intensity of the ring beam surrounding the central spot beam.

[0008] [Outline of the embodiment] First, the embodiments of the present disclosure will be listed and described.

[0009] (1) A variable optical beam shaper 10 according to a first aspect of the present disclosure includes a diffractive optical system 12. The diffractive optical system 12 includes a first diffractive optical element and a second diffractive optical element. The first diffractive optical element and the second diffractive optical element can generate a first beam 3 a and a second beam 3 b having different diffraction orders from a laser beam 3 incident on the diffractive optical system 12. The diffractive optical system 12 can generate a central spot beam 18 and a ring beam 19 around the central spot beam 18 from the first beam 3 a and the second beam 3 b, respectively. One of the first diffractive optical element and the second diffractive optical element is configured to be rotatable about an optical axis O of the diffractive optical system 12 relative to the other of the first diffractive optical element and the second diffractive optical element. The first and second diffractive optical elements are the first and second spiral axicon diffractive optical elements 13 and 14, or are the first and second spiral diffractive optical elements 13a and 14a, respectively, having a periodic phase distribution in the radial direction. The periodic phase distribution is symmetric within one period of the periodic phase distribution. In the periodic phase distribution, the phase changes stepwise in the radial direction by a number of steps greater than two, or the phase changes continuously in the radial direction.

[0010] Because the relative angle between the first diffractive optical element and the second diffractive optical element about the optical axis O of the diffractive optical system 12 can change, the ratio of the first intensity of the central spot beam 18 to the second intensity of the ring beam 19 can change.

[0011] (2) In the variable optical beam shaper 10 according to (1) above, the first and second diffractive optical elements are a first spiral axicon diffractive optical element 13 and a second spiral axicon diffractive optical element 14. The first spiral axicon diffractive optical element 13 has a first phase distribution φ1(r, θ) expressed by the following equation (1). The second spiral axicon diffractive optical element 14 has a second phase distribution φ2(r, θ) expressed by the following equation (2). φ1(r, θ)=a1·r+m1·θ+ψi1 ... (1) φ2(r, θ)=a2·r+m2·θ+ψi2 ... (2) Note that the physical quantities and coefficients appearing in the above equations (1) and (2) satisfy the following conditions: r is the distance in the radial direction in polar coordinates. The above r is a physical quantity having the dimension of length. θ is the deflection angle in polar coordinates. a1 and a2 are each coefficients having a dimension of the reciprocal of the length, and are real numbers excluding zero. a2 / a1 is equal to or greater than 0.97 and equal to or less than 1.03. m1 and m2 are each real numbers excluding zero. m2 / m1 is equal to or greater than 0.95 and equal to or less than 1.05. ψi1 and ψi2 are initial phases and are arbitrary real numbers.

[0012] Because the relative angle may vary, the ratio of the first intensity of the central spot beam 18 to the second intensity of the ring beam 19 may vary.

[0013] (3) In the variable optical beam shaper 10 according to (1) or (2) above, the first diffractive optical element and the second diffractive optical element are a first spiral axicon diffractive optical element 13 and a second spiral axicon diffractive optical element 14. The first spiral axicon diffractive optical element 13 is a first binary diffractive optical element. The second spiral axicon diffractive optical element 14 is a second binary diffractive optical element.

[0014] Because the relative angle may vary, the ratio of the first intensity of the central spot beam 18 to the second intensity of the ring beam 19 may vary.

[0015] (4) In the variable optical beam shaper 10 according to (3) above, the first binary diffractive optical element has a first phase step Δφ1. The second binary diffractive optical element has a second phase step Δφ2. The diffractive optical system 12 satisfies any of the following conditional expressions (3) to (6). 0.9π≦mod 2π(Δφ1)≦1.1π (3) 0.9π≦mod 2π(Δφ2)≦1.1π (4) 0.9π≦mod 2π(Δφ1 + Δφ2)≦1.1π (5) 0.9π≦|mod 2π(Δφ1)−mod 2π(Δφ2)|≦1.1π (6) where mod 2π( ) is a modulo operation of 2π.

[0016] Therefore, the adjustable range of the ratio between the first intensity of the central spot beam 18 and the second intensity of the ring beam 19 can be expanded.

[0017] (5) In the variable optical beam shaper 10 according to (3) above, the first binary diffractive optical element has a first phase step Δφ1. The second binary diffractive optical element has a second phase step Δφ2. The diffractive optical system 12 satisfies the following conditional expressions (7) and (8). 0.9π≦mod 2π(Δφ1)+mod 2π(Δφ2)≦3.3π... (7) 0.9π≦|mod 2π(Δφ1)−mod 2π(Δφ2)|≦1.1π... (8) where mod 2π( ) is a modulo operation of 2π.

[0018] Therefore, the adjustable range of the ratio between the first intensity of the central spot beam 18 and the second intensity of the ring beam 19 can be expanded.

[0019] (6) In the variable optical beam shaper 10 according to (1) or (2) above, the first diffractive optical element and the second diffractive optical element are a first spiral axicon diffractive optical element 13 and a second spiral axicon diffractive optical element 14. The first spiral axicon diffractive optical element 13 is a first multi-level diffractive optical element. The number of phase steps of the first multi-level diffractive optical element is a natural number greater than 2. The second spiral axicon diffractive optical element 14 is a second multi-level diffractive optical element having the above number of phase steps.

[0020] This improves the diffraction efficiency of the diffractive optical system 12. The second intensity of the ring beam 19 increases. Also, splitting of the ring beam 19 can be reduced or eliminated.

[0021] (7) In the variable optical beam shaper 10 according to (6) above, the first multi-level diffractive optical element has a first maximum phase step Δφ1. The second multi-level diffractive optical element has a second maximum phase step Δφ2. The diffractive optical system 12 satisfies the following conditional expressions (9) and (10), or satisfies the following conditional expression (11): 0.9π≦mod 2π(Δφ1)≦1.1π (9) 0.9π≦mod 2π(Δφ2)≦1.1π (10) 0.9×2π(s−1) / s≦mod 2π(Δφ1+Δφ2)≦1.1×2π(s−1) / s (11) where s is the number of phase steps, and mod 2π( ) is a modulo operation of 2π.

[0022] Therefore, the adjustable range of the ratio between the first intensity of the central spot beam 18 and the second intensity of the ring beam 19 can be expanded.

[0023] (8) In the variable optical beam shaper 10 according to (1) or (2) above, the first diffractive optical element and the second diffractive optical element are a first spiral axicon diffractive optical element 13 and a second spiral axicon diffractive optical element 14. The first spiral axicon diffractive optical element 13 is a first blazed diffractive optical element. The second spiral axicon diffractive optical element 14 is a second blazed diffractive optical element.

[0024] This further improves the diffraction efficiency of the diffractive optical system 12. The second intensity of the ring beam 19 increases. Also, splitting of the ring beam 19 can be reduced or eliminated.

[0025] (9) In the variable optical beam shaper 10 according to (8) above, the first blazed diffractive optical element has a first maximum phase step Δφ1. The second blazed diffractive optical element has a second maximum phase step Δφ2. The diffractive optical system 12 satisfies the following conditional expressions (12) and (13): 0.9π≦mod 2π(Δφ1)≦1.1π (12) 0.9π≦mod 2π(Δφ2)≦1.1π (13) where mod 2π( ) is a modulo operation of 2π.

[0026] Therefore, the adjustable range of the ratio between the first intensity of the central spot beam 18 and the second intensity of the ring beam 19 can be expanded.

[0027] (10) In the variable beam shaper 10 according to (1) above, the first and second diffractive optical elements are a first spiral diffractive optical element 13a and a second spiral diffractive optical element 14a. The first spiral diffractive optical element 13a has a first phase distribution φ1(r, θ) expressed by the following equation (14). The second spiral diffractive optical element 14a has a second phase distribution φ2(r, θ) expressed by the following equation (15).

[0028] φ1(r, θ) = f1(a1·r + m1·θ) ... (14) φ2(r, θ) = f2(a2·r + m2·θ) ... (15) Here, r is the radial distance in polar coordinates. r is a physical quantity having the dimension of length. θ is the argument of polar coordinates. a1 and a2 are each coefficients having the dimension of the reciprocal of length, and their numerical values ​​are real numbers excluding zero. a2 / a1 is equal to or greater than 0.97 and equal to or less than 1.03. m1 and m2 are each real numbers excluding zero. m2 / m1 is equal to or greater than 0.95 and equal to or less than 1.05. The function f1(a1·r + m1·θ) satisfies the following equations (16) and (17). The function f2(a2·r + m2·θ) satisfies the following equations (18) and (19).

[0029] f1(a1·r+m1·θ)=f1(a1·(r+2π / a1)+m1·θ) (16) f1(a1·r+m1·θ)+f1(a1·(r+π / a1)+m1·θ)=first constant (17) f2(a2·r+m2·θ)=f2(a2·(r+2π / a2)+m2·θ) (18) f2(a2·r+m2·θ)+f2(a2·(r+π / a2)+m2·θ)=second constant (19) The first constant and the second constant are constants that are independent of r and θ, respectively.

[0030] Therefore, the second intensity of the ring beam 19 can be further decreased and the first intensity of the central spot beam 18 can be further increased, thereby further widening the adjustable range of the ratio between the first intensity of the central spot beam 18 and the second intensity of the ring beam 19.

[0031] (11) In the variable optical beam shaper 10 according to (1) or (10), the first and second diffractive optical elements are first and second spiral diffractive optical elements each having a periodic phase distribution in the radial direction. The periodic phase distribution is a stepped triangular wave phase distribution or a continuously changing triangular wave phase distribution.

[0032] Therefore, the second intensity of the ring beam 19 can be further decreased and the first intensity of the central spot beam 18 can be further increased, thereby further widening the adjustable range of the ratio between the first intensity of the central spot beam 18 and the second intensity of the ring beam 19.

[0033] (12) In the variable optical beam shaper 10 according to (11) above, the difference between the maximum and minimum phase values ​​in one period of the phase distribution is 0.9π to 1.1π.

[0034] Therefore, the second intensity of the ring beam 19 can be further decreased and the first intensity of the central spot beam 18 can be further increased. In particular, when the difference between the maximum phase value and the minimum phase value is π, the second intensity of the ring beam 19 can be completely zero. This allows the adjustable range of the ratio between the first intensity of the central spot beam 18 and the second intensity of the ring beam 19 to be further expanded.

[0035] (13) In the variable optical beam shaper 10 according to (1) or (10), the first and second diffractive optical elements are first and second spiral diffractive optical elements each having a periodic phase distribution in the radial direction. The periodic phase distribution is a stepped sinusoidal phase distribution or a continuously varying sinusoidal phase distribution.

[0036] Therefore, the second intensity of the ring beam 19 can be further decreased and the first intensity of the central spot beam 18 can be further increased, thereby further widening the adjustable range of the ratio between the first intensity of the central spot beam 18 and the second intensity of the ring beam 19.

[0037] (14) In the variable optical beam shaper 10 according to (13) above, the difference between the maximum and minimum phase values ​​in one period of the phase distribution is equal to or greater than 0.68904π and equal to or less than 0.84216π.

[0038] Therefore, the second intensity of the ring beam 19 can be further decreased and the first intensity of the central spot beam 18 can be further increased. In particular, when the difference between the maximum and minimum phase values ​​is 0.7656π, the second intensity of the ring beam 19 can be completely zero. This allows the adjustable range of the ratio between the first intensity of the central spot beam 18 and the second intensity of the ring beam 19 to be further expanded.

[0039] (15) The variable optical beam shaper 10 according to any one of (1) to (14) above further includes a first variable magnification optical system 15. The first diffractive optical element and the second diffractive optical element are arranged in this order in the traveling direction of the laser beam 3. In the direction of the optical axis O of the diffractive optical system 12, the first variable magnification optical system 15 is arranged on the opposite side of the second diffractive optical element from the first diffractive optical element.

[0040] By changing the magnification of the first variable magnification optical system 15, the spot diameter Dc of the central spot beam 18 and the ring diameter Dr of the ring beam 19 can be changed.

[0041] (16) The variable optical beam shaper 10 according to (15) above further includes a second variable magnification optical system 16. In the direction of the optical axis O, the second variable magnification optical system 16 is disposed on the opposite side of the first diffractive optical element from the side of the second diffractive optical element.

[0042] By changing the magnification of the first variable magnification optical system 15 and the magnification of the second variable magnification optical system 16, the spot diameter Dc of the central spot beam 18 and the ring diameter Dr of the ring beam 19 can be changed independently of each other.

[0043] (17) A variable optical beam shaper 10 according to a second aspect of the present disclosure includes a diffractive optical system 12. The diffractive optical system 12 includes a first diffractive optical element and a second diffractive optical element. The first diffractive optical element and the second diffractive optical element can generate a first beam 3 a and a second beam 3 b having different diffraction orders from a laser beam 3 incident on the diffractive optical system 12. The diffractive optical system 12 can generate a central spot beam 18 and a ring beam 19 around the central spot beam 18 from the first beam 3 a and the second beam 3 b, respectively. One of the first diffractive optical element and the second diffractive optical element is configured to be movable in the direction of an optical axis O of the diffractive optical system 12 relative to the other of the first diffractive optical element and the second diffractive optical element. The first and second spiral axicon diffractive optical elements are the first and second spiral axicon diffractive optical elements 13 and 14, respectively, or are the first and second spiral axicon diffractive optical elements 13a and 14a, respectively, each having a periodic phase distribution in the radial direction, or are the first and second axicon diffractive optical elements 13b and 14b, respectively. The periodic phase distribution is symmetric within one period of the periodic phase distribution. In the periodic phase distribution, the phase changes stepwise in the radial direction by a number of steps greater than two, or the phase changes continuously in the radial direction.

[0044] Since the relative distance between the first diffractive optical element and the second diffractive optical element in the direction of the optical axis O of the diffractive optical system 12 can change, the ratio of the first intensity of the central spot beam 18 to the second intensity of the ring beam 19 can change.

[0045] (18) The variable optical beam shaper 10 according to (17) above further includes a first variable magnification optical system 15. The first diffractive optical element and the second diffractive optical element are arranged in this order in the direction of propagation of the laser beam 3. In the direction of the optical axis O, the first variable magnification optical system 15 is arranged on the opposite side of the second diffractive optical element from the side of the first diffractive optical element.

[0046] By changing the magnification of the first variable magnification optical system 15, the spot diameter Dc of the central spot beam 18 and the ring diameter Dr of the ring beam 19 can be changed.

[0047] (19) The variable optical beam shaper 10 according to (18) above further includes a second variable magnification optical system 16. In the direction of the optical axis O, the second variable magnification optical system 16 is disposed on the opposite side of the first diffractive optical element from the side of the second diffractive optical element.

[0048] By changing the magnification of the first variable magnification optical system 15 and the magnification of the second variable magnification optical system 16, the spot diameter Dc of the central spot beam 18 and the ring diameter Dr of the ring beam 19 can be changed independently of each other.

[0049] (20) The laser processing device 1 of the present disclosure includes the variable optical beam shaper 10 according to any one of (1) to (19) above.

[0050] The ratio between the first intensity of the center spot beam 18 and the second intensity of the ring beam 19 can be appropriately adjusted depending on the type of workpiece W, the scanning speed of the center spot beam 18 and the ring beam 19 relative to the workpiece W, etc. This can improve at least one of the speed and quality of laser processing.

[0051] [Details of the embodiment] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In the following drawings, the same or corresponding parts are designated by the same reference numerals, and description thereof will not be repeated.

[0052] First Embodiment A laser processing apparatus 1 and a variable optical beam shaper 10 according to a first embodiment will be described with reference to FIGS. 1 to 32B.

[0053] 1 , a laser processing apparatus 1 is used for drilling, cutting, or welding a workpiece W. The laser processing apparatus 1 mainly includes a laser light source 2, an optical fiber 4, a variable optical beam shaper 10, a stage 7, and a stage driving device 8.

[0054] The laser light source 2 is a solid-state laser such as a fiber laser, a semiconductor laser, or a YAG laser, or a gas laser such as a carbon dioxide laser. The laser light source 2 outputs a laser beam 3. The laser beam 3 may be a single-mode laser beam or a multi-mode laser beam.

[0055] The optical fiber 4 includes a core and a cladding around the core. The optical fiber 4 transmits the laser beam 3 output from the laser light source 2 to the variable optical beam shaper 10. The laser beam 3 mainly propagates through the core of the optical fiber 4. The optical fiber 4 is, for example, a quartz optical fiber.

[0056] The variable optical beam shaper 10 includes a diffractive optical system 12. The variable optical beam shaper 10 may further include a collimating lens 11 and a driving device 6.

[0057] The collimating lens 11 collimates the laser beam 3 emitted from the optical fiber 4. The collimated laser beam 3 enters the diffractive optical system 12.

[0058] The diffractive optical system 12 includes a first spiral axicon diffractive optical element 13 and a second spiral axicon diffractive optical element 14. The diffractive optical system 12 may further include a condenser lens 17. The collimator lens 11, the first spiral axicon diffractive optical element 13, the second spiral axicon diffractive optical element 14, and the condenser lens 17 are arranged in this order in the traveling direction of the laser beam 3 incident on the diffractive optical system 12.

[0059] The first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 have a spiral phase distribution (see, for example, FIGS. 3, 10, 17, 25, and 31) and are optical elements that generate p-th order diffracted beams (p is an integer). The p-th order diffracted beams are, for example, ±1st order diffracted beams. The spiral axicon diffractive optical element is a binary diffractive optical element, a multi-level diffractive optical element, or a blazed diffractive optical element that has a spiral phase distribution and a constant phase gradient in the radial direction.

[0060] Specifically, the first spiral axicon diffractive optical element 13 has a first phase distribution φ1(r, θ) represented by the above formula (1). The second spiral axicon diffractive optical element 14 has a second phase distribution φ2(r, θ) represented by the above formula (2). m1 is the topological charge of the spiral phase pattern of the first spiral axicon diffractive optical element 13. m2 is the topological charge of the spiral phase pattern of the second spiral axicon diffractive optical element 14. The topological charge is a parameter representing the number of rotations and direction of the spiral of the phase pattern.

[0061] In the region of the first spiral axicon diffractive optical element 13 that is irradiated with the laser beam 3, the spiral phase distribution of the first spiral axicon diffractive optical element 13 is uninterrupted and formed continuously from the center of the phase distribution (center of the vortex). In the region of the second spiral axicon diffractive optical element 14 that is irradiated with the laser beam 3, the spiral phase distribution of the second spiral axicon diffractive optical element 14 is uninterrupted and formed continuously from the center of the phase distribution (center of the vortex). r is the radial distance in polar coordinates with the center of the phase distribution (center of the vortex) as the origin. r is a physical quantity having the dimension of length. The unit of r is, for example, mm. θ is the deflection angle of the polar coordinates. θ is a dimensionless physical quantity. The unit of θ is rad. a1 and a2 are each coefficients having the dimension of the reciprocal of length, and their numerical values ​​are real numbers excluding zero. The units of the above a1 and a2 are, for example, mm －１ where m1 and m2 are real numbers excluding zero, and ψi1 and ψi2 are initial phases and are arbitrary real numbers.

[0062] The condenser lens 17 condenses the laser beams (first beam 3 a, second beam 3 b) emitted from the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 onto the focal plane of the condenser lens 17.

[0063] The diffractive optical system 12 can generate a first beam 3a and a second beam 3b having different diffraction orders from the laser beam 3 incident on the diffractive optical system 12. The first beam 3a is, for example, a zeroth-order diffracted beam generated by a composite phase imparted to the laser beam 3 by the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14. The second beam 3b is, for example, a ±1st-order diffracted beam generated by a composite phase imparted to the laser beam 3 by the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14. The diffractive optical system 12 can generate a central spot beam 18 from the first beam 3a and a ring beam 19 around the central spot beam 18 from the second beam 3b. For example, the central spot beam 18 is generated by focusing the first beam 3a with the focusing lens 17. The ring beam 19 is generated by focusing the second beam 3b with the focusing lens 17.

[0064] The ring diameter Dr of the ring beam 19 is given by equation (20). Note that when the variable optical beam shaper 10 generates multiple ring beams 19, the ring diameter Dr is the ring diameter of the innermost ring beam 19. Dr=2×f×θ ｄ ...(20) where f is the focal length of the condenser lens 17, and θ ｄ is the diffraction angle of the laser beam 3 due to the composite phase imparted to the laser beam 3 by the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14.

[0065] The diffraction angle θ ｄ is given by equation (21): sin θ ｄ = λ / d １ ...(21) where λ is the wavelength of the laser beam 3, and d １ is the period of the composite phase that the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 impart to the laser beam 3.

[0066] For example, the period d of the composite phase １is the phase period d of each of the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14. ２ When the ring diameter Dr of the ring beam 19 is equal to the ring diameter D of the ring beam generated by each of the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 alone, ０ The period of the composite phase is d １ is the phase period d of each of the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14. ２ When the ring diameter Dr of the ring beam 19 is half of the ring diameter D of the ring beam generated by each of the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 alone, ０ It is twice as much.

[0067] The driving device 6 is connected to, for example, the second spiral axicon diffractive optical element 14. The driving device 6 includes, for example, a rotation stage (not shown) on which the second spiral axicon diffractive optical element 14 is mounted, and a motor (not shown) for rotating the rotation stage. The driving device 6 rotates the second spiral axicon diffractive optical element 14 about the optical axis O of the diffractive optical system 12, thereby changing the relative angle between the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 about the optical axis O of the diffractive optical system 12. Note that the driving device 6 may be connected to the first spiral axicon diffractive optical element 13, and may rotate the first spiral axicon diffractive optical element 13 about the optical axis O of the diffractive optical system 12 to change the relative angle.

[0068] When the relative angle changes, as shown in Figures 8A, 8B, 9A, and 9B, for example, one of the first phase distribution φ1(r, θ) of the first spiral axicon diffractive optical element 13 and the second phase distribution φ2(r, θ) of the second spiral axicon diffractive optical element 14 is shifted in the radial direction with respect to the other of the first phase distribution φ1(r, θ) and the second phase distribution φ2(r, θ). The composite phase that the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 impart to the laser beam 3 changes. The composite phase is the sum of the first phase distribution φ1(r, θ) and the second phase distribution φ2(r, θ-α), where α is the relative angle. The first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 are arranged close to each other to such an extent that the phases that the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 impart to the laser beam 3 can be considered to be the above-mentioned composite phase.

[0069] The change in composite phase changes the ratio between the first intensity of the center spot beam 18 and the second intensity of the ring beam 19. The first intensity of the center spot beam 18 is the maximum intensity of the center spot beam 18. The second intensity of the ring beam 19 is the maximum intensity of the ring beam 19.

[0070] The housing 5a houses the collimating lens 11 and the diffractive optical system 12. A window 5b is provided at the output end of the housing 5a. The window 5b is made of, for example, quartz glass. The first beam 3a and the second beam 3b generated by the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 pass through the window 5b and proceed toward the workpiece W. The diffractive optical system 12, the housing 5a, and the window 5b constitute the optical head 5 of the laser processing apparatus 1.

[0071] The stage 7 is a three-axis stage that is movable, for example, in the x direction (see FIG. 1), the y direction (see FIG. 1), and the z direction (see FIG. 1). The stage 7 has a workpiece mounting surface 7a on which the workpiece W is placed. The workpiece mounting surface 7a extends, for example, in the x direction and the y direction. The workpiece W is placed on the workpiece mounting surface 7a. The workpiece W is irradiated with a central spot beam 18 and a ring beam 19, and is machined using the central spot beam 18 and the ring beam 19.

[0072] The stage driving device 8 is connected to, for example, the stage 7 and moves the stage 7. The stage driving device 8 changes the relative position of the workpiece W with respect to the optical head 5. Therefore, the center spot beam 18 and the ring beam 19 scan the workpiece W. In order to scan the center spot beam 18 and the ring beam 19 with respect to the workpiece W, the optical head 5 may be moved instead of moving the stage 7.

[0073] In this embodiment, the first spiral axicon diffractive optical element 13 is a first binary diffractive optical element. The second spiral axicon diffractive optical element 14 is a second binary diffractive optical element. The binary diffractive optical element is a diffractive optical element with two phase steps. The first binary diffractive optical element has a first phase step Δφ1 (see FIGS. 8A , 9A , 15A , 16A , 23A , and 24A ). The second binary diffractive optical element has a second phase step Δφ2 (see FIGS. 8B , 9B , 15B , 16B , 23B , and 24B ). The diffractive optical system 12 may satisfy any one of the above conditional expressions (3) to (6), or may satisfy the above conditional expressions (7) and (8). This allows for a wider adjustable range for the ratio between the first intensity of the central spot beam 18 and the second intensity of the ring beam 19. In the above conditional expression, mod2π( ) is a modulo operation of 2π, that is, the remainder when the value in the parentheses is divided by 2π.

[0074] If laser beam 3 is a single-mode laser beam, multiple splits occur in ring beam 19, as shown in Figures 5B, 6B, 7B, 11B, 12B, 20B, 21B, and 22B. By using a multi-mode laser beam as laser beam 3, it is possible to prevent multiple splits from occurring in ring beam 19. It is also possible to make the intensity of ring beam 19 more uniform in the circumferential direction of ring beam 19.

[0075] (Examples) First to fifth examples of this embodiment will be described with reference to Figs. 3 to 32B.

[0076] 3 to 9C and Tables 1 and 2. Table 1 shows the simulation conditions for the first embodiment.

[0077]

[0078] As shown in Table 1, Figure 3, Figures 8A and 8B, in the first embodiment, the first diffractive optical element is a first spiral axicon diffractive optical element 13 having m1 of 1. The second diffractive optical element is a second spiral axicon diffractive optical element 14 having m2 of 1. m2 / m1 is 1. Δφ1 and Δφ2 are π. a1 is equal to a2, and a2 / a1 is 1. ψi1 is equal to ψi2. The number of phase steps s of the first spiral axicon diffractive optical element 13 and the number of phase steps s of the second spiral axicon diffractive optical element 14 are each 2. That is, the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 are binary diffractive optical elements. The phase period d of each of the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 is 2. ２ The ring diameter D of the ring beam generated by each of the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 is 426 μm. ０ is 1.0 mm.

[0079] The wavelength of the laser beam 3 is 1064 nm. The laser beam 3 is a single-mode laser beam. The beam diameter (1 / e ２ In this specification, the beam diameter (1 / e ２ ) is 1 / e of the maximum intensity of the laser beam ２ The focal length of the condenser lens 17 is 200 mm.

[0080] The first spiral axicon diffractive optical element 13 does not rotate, and as shown in Figures 8A and 9A, the first phase distribution φ1(r, θ) of the first spiral axicon diffractive optical element 13 does not change. In contrast, the driving device 6 rotates the second spiral axicon diffractive optical element 14 around the optical axis O of the diffractive optical system 12. This changes the above-mentioned relative angle. When the second spiral axicon diffractive optical element 14 rotates, the second phase distribution φ2(r, θ) of the second spiral axicon diffractive optical element 14 is shifted in the radial direction, as shown in Figures 8B and 9B. Thus, the second phase distribution φ2(r, θ) of the second spiral axicon diffractive optical element 14 is shifted in the radial direction with respect to the first phase distribution φ1(r, θ) of the first spiral axicon diffractive optical element 13.

[0081] Therefore, as shown in Figures 4A, 5A, 6A, 7A, 8C, and 9C, the composite phase that the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 impart to the laser beam 3 changes. Because the composite phase changes, the ratio between the first intensity of the central spot beam 18 and the second intensity of the ring beam 19 changes, as shown in Figures 4B, 4C, 5B, 5C, 6B, 6C, 7B, and 7C.

[0082] The corresponding values ​​of the above conditional expressions (3) to (8) in the first embodiment are as shown in Table 2. The first embodiment satisfies conditional expressions (3), (4), and (7). Therefore, as shown in FIGS. 4B, 4C, 5B, 5C, 6B, 6C, 7B, and 7C, the ratio of the first intensity of the central spot beam 18 to the second intensity of the ring beam 19 can be changed from 0:1 to 1:0. This allows for a wider adjustable range of the ratio of the first intensity to the second intensity.

[0083]

[0084] Specifically, when the relative angle is 0 degree as shown in Figures 8A and 8B, the composite phase calculated modulo 2π is equal in phase over the entire cross section of the laser beam 3 as shown in Figures 4A and 8C. Therefore, the laser beam 3 is not diffracted by the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14, but passes through the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14, and is focused by the focusing lens 17. As shown in Figures 4B and 4C, the diffractive optical system 12 generates a central spot beam 18 but does not generate a ring beam 19.

[0085] In contrast, when the relative angle is 90 degrees as shown in Figures 9A and 9B, the composite phase calculated modulo 2π has a spiral phase distribution as shown in Figures 7A and 9C. The average value of the composite phase calculated modulo 2π is 0.5π. Generally, when the average value Pav of the phase of the diffractive optical element calculated modulo 2π satisfies the following equation (22), all of the laser beams incident on the diffractive optical element are diffracted. Pav = π(s - 1) / s (22), where s is the number of phase steps of the diffractive optical element.

[0086] In the first embodiment, the average value Pav of the composite phase calculated modulo 2π is 0.5π, and the number of phase steps s of the composite phase is 2. The first embodiment satisfies equation (22). Therefore, when the relative angle is 90 degrees, the entire laser beam 3 is diffracted by the diffractive optical system 12, as shown in Figures 7B and 7C. That is, the diffractive optical system 12 generates the ring beam 19 but does not generate the central spot beam 18.

[0087] As shown in FIGS. 7A and 9C, the period d of the composite phase １ is the phase period d of each of the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14. ２ 7C, the ring diameter Dr of the ring beam 19 generated by the diffractive optical system 12 is half the ring diameter D of the ring beams generated by each of the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 alone. ０ It will be twice as much.

[0088] As the relative angle increases from 0 degrees to 90 degrees, the composite phase changes as shown in Figures 5A and 6A, making it easier for diffraction to occur in the diffractive optical system 12. Therefore, as shown in Figures 5B, 5C, 6B, and 6C, the first intensity of the central spot beam 18 gradually decreases and the second intensity of the ring beam 19 gradually increases. In this way, the ratio of the first intensity of the central spot beam 18 to the second intensity of the ring beam 19 can be changed from 0:1 to 1:0.

[0089] 10 to 16C and Tables 3 and 4. Simulation conditions for the second embodiment are shown in Table 3.

[0090]

[0091] The first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 of the second example are configured similarly to the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 of the first example, but as shown in Table 3, Figures 10, 15A and 15B, in the second example, Δφ1 and Δφ2 are 0.5π. The other simulation conditions for the second example are the same as those for the first example.

[0092] As described in the first embodiment, when the relative angle changes, the second phase distribution φ(r, θ) of the second spiral axicon diffractive optical element 14 is shifted in the radial direction with respect to the first phase distribution φ(r, θ) of the first spiral axicon diffractive optical element 13. Therefore, as shown in Figures 11A, 12A, 13A, 14A, 15C, and 16C, the composite phase that the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 impart to the laser beam 3 changes. Because the composite phase changes, the ratio between the first intensity of the central spot beam 18 and the second intensity of the ring beam 19 changes, as shown in Figures 11B, 11C, 12B, 12C, 13B, 13C, 14B, and 14C.

[0093] The corresponding values ​​of the above conditional expressions (3) to (8) in the second embodiment are as shown in Table 4. The second embodiment satisfies conditional expressions (5) and (7). Therefore, as shown in FIGS. 11B, 11C, 12B, 12C, 13B, 13C, 14B, and 14C, the ratio of the first intensity of the central spot beam 18 to the second intensity of the ring beam 19 can be changed from 0:1 to 1:0. This allows for a wider adjustable range of the ratio of the first intensity to the second intensity.

[0094]

[0095] Specifically, when the relative angle is 0 degrees as shown in Figures 15A and 15B, the composite phase calculated modulo 2π has a spiral phase distribution as shown in Figures 11A and 15C. The average value Pav of the composite phase calculated modulo 2π is 0.5π, and the number of phase steps s of the composite phase is 2. The second embodiment satisfies equation (22). Therefore, when the relative angle is 0 degrees, the entire laser beam 3 is diffracted by the diffractive optical system 12 as shown in Figures 11B and 11C. That is, the diffractive optical system 12 generates a ring beam 19 but does not generate a central spot beam 18.

[0096] As shown in FIGS. 11A and 15C, the period d of the composite phase １ is the phase period d of each of the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14. ２ 11C, the ring diameter Dr of the ring beam 19 generated by the diffractive optical system 12 is equal to the ring diameter D of the ring beams generated individually by each of the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14. ０ is equal to.

[0097] 16A and 16B, when the relative angle is 180 degrees, as shown in Figures 14A and 16C, the composite phase calculated modulo 2π is equal in phase over the entire cross section of the laser beam 3. Therefore, the laser beam 3 is not diffracted by the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14, but passes through the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14, and is focused by the focusing lens 17. As shown in Figures 14B and 14C, the diffractive optical system 12 generates a central spot beam 18 but does not generate a ring beam 19.

[0098] As the relative angle increases from 0 degrees to 180 degrees, the composite phase changes as shown in Figures 12A, 13A, and 14A, and diffraction becomes increasingly difficult to occur in the diffractive optical system 12. Therefore, as shown in Figures 12B, 12C, 13B, 13C, 14B, and 14C, the first intensity of the central spot beam 18 gradually increases and the second intensity of the ring beam 19 gradually decreases. In this way, the ratio of the first intensity of the central spot beam 18 to the second intensity of the ring beam 19 can be changed from 0:1 to 1:0.

[0099] 17 to 24E and Tables 5 and 6, the variable optical beam shaper 10 of the third embodiment will be described. Table 5 shows the simulation conditions for the third embodiment.

[0100]

[0101] The first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 of the third example are configured similarly to the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 of the first example, but in the third example, Δφ1 is π and Δφ2 is 0.5π, as shown in Table 5, Figures 17, 18, 23A and 23B. The other simulation conditions of the third example are the same as those of the first example.

[0102] As described in the first embodiment, when the relative angle changes, the second phase distribution φ(r, θ) of the second spiral axicon diffractive optical element 14 is shifted in the radial direction with respect to the first phase distribution φ(r, θ) of the first spiral axicon diffractive optical element 13. Therefore, as shown in Figures 19A, 20A, 21A, 22A, 23C, and 24C, the composite phase that the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 impart to the laser beam 3 changes. Because the composite phase changes, the ratio between the first intensity of the central spot beam 18 and the second intensity of the ring beam 19 changes, as shown in Figures 19B, 19C, 20B, 20C, 21B, 21C, 22B, and 22C.

[0103] The corresponding values ​​of the above conditional expressions (3) to (8) in the third embodiment are as shown in Table 6. The third embodiment satisfies conditional expressions (3) and (7). Therefore, as shown in FIGS. 19B, 19C, 20B, 20C, 21B, 21C, 22B, and 22C, the ratio of the first intensity of the central spot beam 18 to the second intensity of the ring beam 19 can be changed from 0:1 to approximately 1:0. This allows for a wider adjustable range of the ratio of the first intensity to the second intensity.

[0104]

[0105] Specifically, when the relative angle is 0 degrees as shown in Figures 23A and 23B, the composite phase calculated modulo 2π has a spiral phase distribution as shown in Figures 19A and 23C. However, in the third embodiment, the average value Pav of the composite phase calculated modulo 2π is 0.75π, and the number of phase steps s is 2. The third embodiment does not satisfy equation (22). Therefore, the diffractive optical system 12 generates, from the laser beam 3, a first beam 3a that is not diffracted by the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14, and a second beam 3b that is diffracted by the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14. The first beam 3a is focused by the focusing lens 17 to form a central spot beam 18. The second beam 3b is focused by the focusing lens 17 to form a ring beam 19. When the relative angle is 0 degrees, the intensity of the central spot beam 18 is dominant and the intensity of the ring beam 19 is dominant, as shown in FIGS. 19B and 19C.

[0106] In contrast, when the relative angle is 90 degrees as shown in Figures 24A and 24B, the composite phase calculated modulo 2π has a phase distribution as shown in Figures 22A and 24C. This composite phase is given by the sum of the first spiral phase component shown in Figure 24D and the second spiral phase component shown in Figure 24E.

[0107] The period of the first spiral phase component shown in FIG. 24D is the period d of the phase of each of the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 shown in FIGS. 24A and 24B. ２ Therefore, as shown in Fig. 22C, the ring diameter Dr1 of the ring beam 19 generated by the first spiral phase component is half the ring diameter D ０ The ring beam 19 generated by the first spiral phase component is a ±2nd order diffracted beam generated by the composite phase imparted to the laser beam 3 by the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14.

[0108] The average phase value Pav of the first spiral phase component shown in Figure 24D is 0.5π, and the number of phase steps s of the first spiral phase component is 2. The first spiral phase component satisfies equation (22). Therefore, when the relative angle is 90 degrees, the entire laser beam 3 is diffracted by the first spiral phase component, as shown in Figures 22B and 22C. That is, the diffractive optical system 12 generates the ring beam 19 but does not generate the central spot beam 18.

[0109] The period of the second spiral phase component shown in FIG. 24E is the period d of the phase of each of the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 shown in FIGS. 24A and 24B. ２ Therefore, as shown in Fig. 22C, the ring diameter Dr2 of the ring beam 19 generated by the second spiral phase component is equal to the ring diameter D ０The ring beams 19 generated by the second spiral phase component are ±1st order diffracted beams generated by the composite phases imparted to the laser beam 3 by the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14.

[0110] Thus, when the relative angle is 90 degrees, the diffractive optical system 12 has a diffraction angle of D ０ a ring beam 19 having a ring diameter of 2D ０ and a ring beam 19 having a ring diameter of .

[0111] As the relative angle increases from 0 degrees to 90 degrees, the composite phase changes as shown in Figures 20A and 21A, making it easier for diffraction to occur in the diffractive optical system 12. Therefore, as shown in Figures 21B, 21C, 22B, and 22C, the first intensity of the central spot beam 18 gradually decreases and the second intensity of each of the two ring beams 19 gradually increases. In this way, the ratio of the first intensity of the central spot beam 18 to the second intensity of each of the two ring beams 19 can be changed from 0:1 to approximately 1:0.

[0112] (Fourth Example) In the first to third examples, m1 and m2 were 1, but even if m1 and m2 are not 1, the ratio between the first intensity of the central spot beam 18 and the second intensity of the ring beam 19 can be changed by changing the relative angle.

[0113] The variable optical beam shaper 10 of the fourth embodiment will be described with reference to Figures 25 to 30C and Table 7. The simulation conditions for the fourth embodiment are shown in Table 7.

[0114]

[0115] The first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 of the fourth example are configured similarly to the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 of the second example, but as shown in Table 7 and Fig. 25, in the fourth example, m1 and m2 are 5. The other simulation conditions of the fourth example are the same as those of the second example.

[0116] As described in the second embodiment, when the relative angle changes, the second phase distribution φ(r, θ) of the second spiral axicon diffractive optical element 14 shifts in the radial direction with respect to the first phase distribution φ(r, θ) of the first spiral axicon diffractive optical element 13. Therefore, as shown in Figures 26A, 27A, 28A, 29A, and 30A, the composite phase that the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 impart to the laser beam 3 changes. Because the composite phase changes, the ratio between the first intensity of the central spot beam 18 and the second intensity of the ring beam 19 changes, as shown in Figures 26B, 26C, 27B, 27C, 28B, 28C, 29B, 29C, 30B, and 30C.

[0117] The corresponding values ​​of the above conditional expressions (3) to (8) in the fourth embodiment are as shown in Table 4. The fourth embodiment satisfies conditional expressions (3) and (7). Therefore, as shown in Figures 26B, 26C, 27B, 27C, 28B, 28C, 29B, 29C, 30B, and 30C, the ratio of the first intensity of the central spot beam 18 to the second intensity of the ring beam 19 can be changed from 0:1 to 1:0. This allows for a wider adjustable range of the ratio of the first intensity to the second intensity.

[0118] Specifically, when the relative angle is 0 degrees, as shown in FIG. 26A, the composite phase calculated modulo 2π has a spiral phase distribution. The average value Pav of the composite phase calculated modulo 2π is 0.5π, and the number of phase steps s of the composite phase is 2. The fourth embodiment satisfies equation (22). Therefore, when the relative angle is 0 degrees, as shown in FIGS. 26B and 26C, the entire laser beam 3 is diffracted by the diffractive optical system 12. That is, the diffractive optical system 12 generates a ring beam 19 but does not generate a central spot beam 18.

[0119] As shown in FIG. 26A, the period d of the composite phase １ is the phase period d of each of the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14. ２ Therefore, as shown in Fig. 26C, the ring diameter Dr of the ring beam 19 generated by the diffractive optical system 12 is equal to the ring diameter D of the ring beams generated individually by each of the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14. ０ is equal to.

[0120] In contrast, when the relative angle is 36 degrees, as shown in Fig. 30A, the composite phase calculated modulo 2π is equal in phase over the entire cross section of the laser beam 3. Therefore, the laser beam 3 is not diffracted by the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14, but passes through the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14, and is focused by the focusing lens 17. As shown in Figs. 30B and 30C, the diffractive optical system 12 generates a central spot beam 18 but does not generate a ring beam 19.

[0121] As the relative angle increases from 0 degrees to 36 degrees, the composite phase changes as shown in Figures 27A, 28A, 29A, and 30A, and diffraction becomes increasingly difficult to occur in the diffractive optical system 12. Therefore, as shown in Figures 27B, 27C, 28B, 28C, 29B, 29C, 30B, and 30C, the first intensity of the central spot beam 18 gradually increases and the second intensity of the ring beam 19 gradually decreases. In this way, the ratio of the first intensity of the central spot beam 18 to the second intensity of the ring beam 19 can be changed from 0:1 to 1:0.

[0122] 31 to 36C and Table 8, the variable optical beam shaper 10 of the fifth embodiment will be described. Table 8 shows the simulation conditions for the fifth embodiment.

[0123]

[0124] The first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 of the fifth example are configured similarly to the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 of the second example, but as shown in Table 8 and Fig. 31, in the fifth example, m1 and m2 are 10. The other simulation conditions of the fifth example are the same as those of the second example.

[0125] As described in the second embodiment, when the relative angle changes, the second phase distribution φ(r, θ) of the second spiral axicon diffractive optical element 14 is shifted in the radial direction with respect to the first phase distribution φ(r, θ) of the first spiral axicon diffractive optical element 13. Therefore, as shown in Figures 32A, 33A, 34A, 35A, and 36A, the composite phase that the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 impart to the laser beam 3 changes. Because the composite phase changes, the ratio between the first intensity of the central spot beam 18 and the second intensity of the ring beam 19 changes, as shown in Figures 32B, 32C, 33B, 33C, 34B, 34C, 35B, 35C, 36B, and 36C.

[0126] The corresponding values ​​of the above conditional expressions (3) to (8) in the fifth embodiment are as shown in Table 4. The fifth embodiment satisfies conditional expressions (3) and (7). Therefore, as shown in Figures 32B, 32C, 33B, 33C, 34B, 34C, 35B, 35C, 36B, and 36C, the ratio of the first intensity of the central spot beam 18 to the second intensity of the ring beam 19 can be changed from 0:1 to 1:0. This allows for a wider adjustable range of the ratio of the first intensity to the second intensity.

[0127] Specifically, when the relative angle is 0 degrees, as shown in FIG. 32A, the composite phase calculated modulo 2π has a spiral phase distribution. The average value Pav of the composite phase calculated modulo 2π is 0.5π, and the number of phase steps s of the composite phase is 2. The fifth embodiment satisfies equation (22). Therefore, when the relative angle is 0 degrees, as shown in FIGS. 32B and 32C, the entire laser beam 3 is diffracted by the diffractive optical system 12. That is, the diffractive optical system 12 generates a ring beam 19 but does not generate a central spot beam 18.

[0128] As shown in FIG. 32A, the period d of the composite phase １ is the phase period d of each of the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14. ２ 32C, the ring diameter Dr of the ring beam 19 generated by the diffractive optical system 12 is equal to the ring diameter D of the ring beams generated individually by each of the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14. ０ is equal to.

[0129] In contrast, when the relative angle is 18 degrees, as shown in Fig. 36A, the composite phase calculated modulo 2π is equal in phase over the entire cross section of the laser beam 3. Therefore, the laser beam 3 is not diffracted by the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14, but passes through the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14, and is focused by the focusing lens 17. As shown in Figs. 36B and 36C, the diffractive optical system 12 generates a central spot beam 18 but does not generate a ring beam 19.

[0130] As the relative angle increases from 0 degrees to 18 degrees, the composite phase changes as shown in Figures 33A, 34A, 35A, and 36A, and diffraction becomes increasingly difficult to occur in the diffractive optical system 12. Therefore, as shown in Figures 33B, 33C, 34B, 34C, 35B, 35C, 36B, and 36C, the first intensity of the central spot beam 18 gradually increases and the second intensity of the ring beam 19 gradually decreases. In this way, the ratio of the first intensity of the central spot beam 18 to the second intensity of the ring beam 19 can be changed from 0:1 to 1:0.

[0131] 26B and 32B, as m1 and m2 increase, the number of split points of ring beam 19 increases. Therefore, as m1 and m2 increase, the period of change in light intensity in the circumferential direction of ring beam 19 becomes smaller, and the light intensity of ring beam 19 in the circumferential direction of ring beam 19 becomes more uniform. In contrast, as m1 and m2 increase, ring beam 19 takes on a shape that leaves a tail on the outside, and the energy density of ring beam 19 decreases. Therefore, when variable light beam shaper 10 is applied to laser processing apparatus 1, it is preferable that the absolute values ​​of m1 and m2 be greater than 0 and equal to or less than 10.

[0132] 1, 2, and 37 to 43C, a laser processing apparatus 1 and a variable optical beam shaper 10 of embodiment 2 will be described. The laser processing apparatus 1 and the variable optical beam shaper 10 of this embodiment are configured similarly to the laser processing apparatus 1 and the variable optical beam shaper 10 of embodiment 1, but differ in the diffractive optical system 12.

[0133] 37 and 38 , in this embodiment, the first spiral axicon diffractive optical element 13 is a first multi-level diffractive optical element. The number of phase steps s of the first multi-level diffractive optical element is a natural number greater than 2. The second spiral axicon diffractive optical element 14 is a second multi-level diffractive optical element having the above-mentioned number of phase steps s.

[0134] The number of phase steps of the first spiral axicon diffractive optical element 13 and the number of phase steps of the second spiral axicon diffractive optical element 14 of this embodiment are larger than the number of phase steps of the first spiral axicon diffractive optical element 13 and the number of phase steps of the second spiral axicon diffractive optical element 14 of Embodiment 1. Therefore, for example, when the number of phase steps of the first spiral axicon diffractive optical element 13 and the number of phase steps of the second spiral axicon diffractive optical element 14 of this embodiment are 16 or more, the diffraction efficiency of the diffractive optical system 12 of this embodiment can be made larger than the diffraction efficiency of the diffractive optical system 12 of Embodiment 1.

[0135] Furthermore, when the number of phase steps of the first spiral axicon diffractive optical element 13 and the number of phase steps of the second spiral axicon diffractive optical element 14 are increased, one of the +q-order diffractive beam (q is a natural number) and the −q-order diffractive beam generated by the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 becomes dominant over the other. Therefore, as shown in Figures 39B, 40B, 41B, and 42B, splitting of ring beam 19 can be reduced or eliminated even if laser beam 3 is a single-mode laser beam.

[0136] The first multi-level diffractive optical element has a first maximum phase step Δφ1. The second multi-level diffractive optical element has a second maximum phase step Δφ2. The diffractive optical system 12 may satisfy the above conditional expressions (9) and (10), or may satisfy the above conditional expression (11). Therefore, the ratio of the first intensity of the central spot beam 18 to the second intensity of the ring beam 19 can be changed from 0:1 to approximately 1:0. The adjustable range of the ratio of the first intensity to the second intensity can be expanded.

[0137] 37 to 44C and Tables 9 and 10, a variable optical beam shaper 10 according to a sixth example of this embodiment will be described. Table 9 shows the simulation conditions for the sixth example.

[0138]

[0139] The first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 of the sixth embodiment are configured in the same manner as the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 of the first embodiment, but as shown in Table 9 and Figures 37 and 38, in the sixth embodiment, the number of phase steps s is 16. That is, in the sixth embodiment, the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 are both multi-level diffractive optical elements having the number of phase steps s of 16. The other simulation conditions for the sixth embodiment are the same as those for the first embodiment.

[0140] As described in the first embodiment, when the relative angle changes, the second phase distribution φ(r, θ) of the second spiral axicon diffractive optical element 14 is shifted in the radial direction with respect to the first phase distribution φ(r, θ) of the first spiral axicon diffractive optical element 13. Therefore, as shown in Figures 39A, 40A, 41A, 42A, 43A, and 44A, the composite phase that the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 impart to the laser beam 3 changes. Because the composite phase changes, the ratio between the first intensity of the central spot beam 18 and the second intensity of the ring beam 19 changes, as shown in Figures 39B, 39C, 40B, 40C, 41B, 41C, 42B, 42C, 43B, 43C, 44A, and 44B.

[0141] The corresponding values ​​of the above conditional expressions (9), (10), and (11) in the sixth embodiment are as shown in Table 10. The sixth embodiment satisfies conditional expressions (9) and (10). Therefore, as shown in Figures 39B, 39C, 40B, 40C, 41B, 41C, 42B, 42C, 43B, 43C, 44A, and 44B, the ratio of the first intensity of the central spot beam 18 to the second intensity of the ring beam 19 can be changed from 0:1 to approximately 1:0. This allows for a wider adjustable range of the ratio of the first intensity to the second intensity.

[0142]

[0143] Specifically, when the relative angle is 0 degrees, as shown in FIG. 39A , the composite phase calculated modulo 2π has a spiral phase distribution. However, in the sixth embodiment, the average value Pav of the composite phase calculated modulo 2π is π, and the number of phase steps s is 16. The sixth embodiment does not satisfy equation (22). Therefore, the diffractive optical system 12 generates, from the laser beam 3, a first beam 3a that is not diffracted by the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14, and a second beam 3b that is diffracted by the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14. As shown in FIGS. 39B and 39C , the first beam 3a is focused by the focusing lens 17 to form a central spot beam 18. The second beam 3b is focused by the focusing lens 17 to form a ring beam 19.

[0144] As shown in FIG. 39A, the period d of the composite phase １ is the phase period d of each of the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14. ２ Therefore, as shown in Fig. 39C, the ring diameter Dr of the ring beam 19 generated by the diffractive optical system 12 is equal to the ring diameter D of the ring beams generated individually by each of the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14. ０ is equal to.

[0145] When the relative angle is a specific angle greater than 0 degrees and less than or equal to 10 degrees, the sixth embodiment satisfies equation (22). When the relative angle is the specific angle, the laser beam 3 is entirely diffracted by the diffractive optics 12. That is, the diffractive optics 12 generates the ring beam 19 but does not generate the central spot beam 18.

[0146] As shown in Figure 40A, when the relative angle is 10 degrees, the sixth embodiment does not satisfy equation (22). Therefore, the diffractive optical system 12 generates a first beam 3a and a second beam 3b from the laser beam 3. When the relative angle is 10 degrees, the intensity of the second beam 3b is dominant and the intensity of the first beam 3a is dominant. As shown in Figures 40B and 40C, the intensity of the ring beam 19 is dominant and the intensity of the central spot beam 18 is dominant.

[0147] When the relative angle is 90 degrees, the composite phase calculated modulo 2π changes as shown in Figure 44A. The diffractive optical system 12 generates a first beam 3a and a second beam 3b from the laser beam 3. The first beam 3a is focused by the focusing lens 17 to become a central spot beam 18. The second beam 3b is focused by the focusing lens 17 to become a ring beam 19. When the relative angle is 90 degrees, the intensity of the first beam 3a is dominant and the intensity of the second beam 3b is dominant. As shown in Figures 44B and 44C, the intensity of the central spot beam 18 is dominant and the intensity of the ring beam 19 is dominant.

[0148] As the relative angle increases from 10 degrees to 90 degrees, the composite phase changes as shown in Figures 40A, 41A, 42A, and 43A, and diffraction becomes increasingly difficult to occur in the diffractive optical system 12. Therefore, as shown in Figures 40B, 40C, 41B, 41C, 42B, 42C, 43B, and 43C, the first intensity of the central spot beam 18 gradually increases and the second intensity of the ring beam 19 gradually decreases. In this way, the ratio of the first intensity of the central spot beam 18 to the second intensity of the ring beam 19 can be changed from 0:1 to approximately 1:0.

[0149] 1, 2, and 45 to 51C, a laser processing apparatus 1 and a variable optical beam shaper 10 of embodiment 3 will be described. The laser processing apparatus 1 and the variable optical beam shaper 10 of this embodiment are configured similarly to the laser processing apparatus 1 and the variable optical beam shaper 10 of embodiment 1, but differ in the diffractive optical system 12.

[0150] As shown in Figures 45, 51A, and 51B, in this embodiment, the first spiral axicon diffractive optical element 13 is a first blazed diffractive optical element. The second spiral axicon diffractive optical element 14 is a second blazed diffractive optical element. The diffraction efficiency of the diffractive optical system 12 of this embodiment is greater than that of the diffractive optical system 12 of Embodiment 2. Furthermore, in a blazed diffractive optical element, one of the +q-order diffracted beam (q is a natural number) and the -q-order diffracted beam generated by the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 becomes dominant over the other. Therefore, as shown in Figures 46B, 47B, and 48B, splitting of the ring beam 19 can be reduced or eliminated even if the laser beam 3 is a single-mode laser beam.

[0151] The first blazed diffractive optical element has a first maximum phase step Δφ1. The second blazed diffractive optical element has a second maximum phase step Δφ2. The diffractive optical system 12 may satisfy the above conditional expressions (12) and (13). Therefore, the ratio of the first intensity of the central spot beam 18 to the second intensity of the ring beam 19 can be changed from 0:1 to approximately 1:0. This allows the adjustable range of the ratio of the first intensity to the second intensity to be expanded.

[0152] 45 to 51C and Tables 11 and 12, a variable optical beam shaper 10 according to a seventh example of this embodiment will be described. Table 11 shows the simulation conditions for the seventh example.

[0153]

[0154] The first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 of the seventh example are configured in the same manner as the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 of the first example, but as shown in Table 11, Figures 45 and 51A, in the seventh example, the number of phase steps s is infinite. That is, in the seventh example, the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 are both blazed diffractive optical elements. The other simulation conditions for the seventh example are the same as those for the first example.

[0155] As described in the first embodiment, when the relative angle changes, the second phase distribution φ(r, θ) of the second spiral axicon diffractive optical element 14 shifts in the radial direction with respect to the first phase distribution φ(r, θ) of the first spiral axicon diffractive optical element 13. Therefore, as shown in Figures 46A, 47A, 48A, 49A, and 50A, the composite phase that the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 impart to the laser beam 3 changes. Because the composite phase changes, the ratio between the first intensity of the central spot beam 18 and the second intensity of the ring beam 19 changes, as shown in Figures 46B, 46C, 47B, 47C, 48B, 48C, 49B, 49C, 50B, and 50C.

[0156] The corresponding values ​​of the above conditional expressions (12) and (13) in the seventh embodiment are as shown in Table 12. The seventh embodiment satisfies conditional expressions (12) and (13). Therefore, as shown in Figures 46B, 46C, 47B, 47C, 48B, 48C, 49B, 49C, 50B, and 50C, the ratio of the first intensity of the central spot beam 18 to the second intensity of the ring beam 19 can be changed from 0:1 to approximately 1:0. This allows for an expanded adjustable range of the ratio of the first intensity to the second intensity.

[0157]

[0158] Specifically, when the relative angle is 0 degrees as shown in Figures 51A and 51B, the composite phase calculated modulo 2π has a spiral phase distribution as shown in Figures 46A and 51C. The average value Pav of the composite phase calculated modulo 2π is π, and the number of phase steps s of the composite phase is infinity. The seventh embodiment satisfies equation (22). Therefore, when the relative angle is 0 degrees, the entire laser beam 3 is diffracted by the diffractive optical system 12 as shown in Figures 46B and 46C. That is, the diffractive optical system 12 generates a ring beam 19 but does not generate a central spot beam 18.

[0159] As shown in FIG. 46A, the period d of the composite phase １ is the phase period d of each of the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14. ２ Therefore, as shown in Fig. 46C, the ring diameter Dr of the ring beam 19 generated by the diffractive optical system 12 is equal to the ring diameter D of the ring beams generated individually by each of the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14. ０ is equal to.

[0160] When the relative angle is 90 degrees, the composite phase calculated modulo 2π changes as shown in Figure 50A. The diffractive optical system 12 generates from the laser beam 3 a first beam 3a that is not diffracted by the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14, and a second beam 3b that is diffracted by the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14. The first beam 3a is focused by the condenser lens 17 to form a central spot beam 18. The second beam 3b is focused by the condenser lens 17 to form a ring beam 19. When the relative angle is 90 degrees, the intensity of the first beam 3a is dominant and the intensity of the second beam 3b is dominant. As shown in Figures 50B and 50C, the intensity of the central spot beam 18 is dominant and the intensity of the ring beam 19 is dominant.

[0161] As the relative angle increases from 0 degrees to 90 degrees, the composite phase changes as shown in Figures 47A, 48A, 49A, and 50A, and diffraction becomes increasingly difficult to occur in the diffractive optical system 12. Therefore, as shown in Figures 47B, 47C, 48B, 48C, 49B, 49C, 50B, and 50C, the first intensity of the central spot beam 18 gradually increases and the second intensity of the ring beam 19 gradually decreases. In this way, the ratio of the first intensity of the central spot beam 18 to the second intensity of the ring beam 19 can be changed from 0:1 to approximately 1:0.

[0162] 1, 2, and 52 to 74C, a laser processing apparatus 1 and a variable optical beam shaper 10 of embodiment 4 will be described. The laser processing apparatus 1 and the variable optical beam shaper 10 of this embodiment are configured similarly to the laser processing apparatus 1 and the variable optical beam shaper 10 of embodiment 2, but differ in the diffractive optical system 12.

[0163] 1 , 52 , 58 , 64 , and 69 , the diffractive optical system 12 of this embodiment includes a first spiral diffractive optical element 13a instead of the first spiral axicon diffractive optical element 13, and a second spiral diffractive optical element 14a instead of the second spiral axicon diffractive optical element 14. The first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a have a spiral phase distribution (see, for example, FIGS. 52 , 58 , 64 , and 69 ), and are optical elements that generate p-th order diffracted beams (p is an integer). The first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a are multi-level diffractive optical elements or blazed diffractive optical elements, among spiral diffractive optical elements, in which the phase gradient is not constant in the radial direction.

[0164] Specifically, the first spiral diffractive optical element 13a has a first phase distribution φ1(r, θ) represented by the above formula (14). The second spiral diffractive optical element 14a has a second phase distribution φ2(r, θ) represented by the above formula (15). m1 is the topological charge of the spiral phase pattern of the first spiral diffractive optical element 13a. m2 is the topological charge of the spiral phase pattern of the second spiral diffractive optical element 14a.

[0165] In the region of the first spiral diffractive optical element 13a that is irradiated with the laser beam 3, the spiral phase distribution of the first spiral diffractive optical element 13a is uninterrupted and is formed continuously from the center of the phase distribution (center of the vortex). In the region of the second spiral diffractive optical element 14a that is irradiated with the laser beam 3, the spiral phase distribution of the second spiral diffractive optical element 14a is uninterrupted and is formed continuously from the center of the phase distribution (center of the vortex). The r is the radial distance of polar coordinates with the center of the phase distribution (center of the vortex) as the origin. The unit of the r is, for example, mm. The θ is a dimensionless physical quantity. The unit of the θ is rad. The units of the a1 and a2 are, for example, mm －１ is.

[0166] The first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a have a periodic phase distribution in the radial direction. This periodic phase distribution has a symmetric phase distribution within one period in the radial direction (see, for example, FIGS. 53, 59, and 70). In this embodiment, the first maximum phase difference Δφ1 is the difference between the maximum and minimum phase values ​​within one period of the periodic phase distribution of the first spiral diffractive optical element 13a. The second maximum phase difference Δφ2 is the difference between the maximum and minimum phase values ​​within one period of the periodic phase distribution of the second spiral diffractive optical element 14a.

[0167] An example of such a radial phase distribution is a step-like wave phase distribution in which the phase changes stepwise in the radial direction by a number of steps greater than two (see, for example, FIGS. 53 and 59). Examples of the step-like wave phase distribution include a step-like triangular wave phase distribution (see FIG. 53) and a step-like sinusoidal wave phase distribution (see FIG. 59). The first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a are, for example, multi-level diffractive optical elements having a number of phase steps s greater than two (see, for example, FIGS. 52, 53, 58, 59, and 64). The first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a are not binary diffractive optical elements.

[0168] Another example of such a radial phase distribution is the phase distribution of a wave whose phase changes continuously in the radial direction (see, for example, FIG. 70). Examples of the phase distribution of a wave whose phase changes continuously in the radial direction include the phase distribution of a sine wave (see, for example, FIG. 70) or the phase distribution of a triangular wave.

[0169] The condenser lens 17 condenses the laser beams (first beam 3 a and second beam 3 b ) emitted from the first spiral diffractive optical element 13 a and the second spiral diffractive optical element 14 a onto the focal plane of the condenser lens 17 .

[0170] The diffractive optical system 12 can generate a first beam 3a and a second beam 3b having different diffraction orders from the laser beam 3 incident on the diffractive optical system 12. The first beam 3a is, for example, a zeroth-order diffracted beam generated by a composite phase imparted to the laser beam 3 by the first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a. The second beam 3b is, for example, a ±1st-order diffracted beam generated by a composite phase imparted to the laser beam 3 by the first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a. The diffractive optical system 12 can generate a central spot beam 18 from the first beam 3a and a ring beam 19 around the central spot beam 18 from the second beam 3b. For example, the central spot beam 18 is generated by focusing the first beam 3a with the focusing lens 17. The ring beam 19 is generated by focusing the second beam 3b with the focusing lens 17.

[0171] The ring diameter Dr of the ring beam 19 is given by equation (20). Note that when the variable optical beam shaper 10 generates multiple ring beams 19, the ring diameter Dr is the ring diameter of the innermost ring beam 19. Dr=2×f×θ ｄ ...(20) where f is the focal length of the condenser lens 17, and θ ｄ is the diffraction angle of the laser beam 3 due to the composite phase imparted to the laser beam 3 by the first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a.

[0172] The diffraction angle θ ｄ is given by equation (21): sin θ ｄ = λ / d １ ...(21) where λ is the wavelength of the laser beam 3, and d １ is the period of the composite phase given to the laser beam 3 by the first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a.

[0173] For example, the period d of the composite phase １ is the phase period d of each of the first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a.２ When the ring diameter Dr of the ring beam 19 is equal to the ring diameter D of the ring beam generated by each of the first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a alone, ０ The period of the composite phase is d １ is the phase period d of each of the first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a. ２ When the ring diameter Dr of the ring beam 19 is half of the ring diameter D of the ring beam generated by each of the first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a alone, ０ It is twice as much.

[0174] The driving device 6 is connected to, for example, the second spiral diffractive optical element 14a. The driving device 6 includes, for example, a rotation stage (not shown) on which the second spiral diffractive optical element 14a is mounted and a motor (not shown) that rotates the rotation stage. The driving device 6 rotates the second spiral diffractive optical element 14a about the optical axis O of the diffractive optical system 12 to change the relative angle between the first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a about the optical axis O of the diffractive optical system 12. Note that the driving device 6 may also be connected to the first spiral diffractive optical element 13a, and may rotate the first spiral diffractive optical element 13a about the optical axis O of the diffractive optical system 12 to change the relative angle.

[0175] When the relative angle changes, one of the first phase distribution φ1(r, θ) of the first spiral diffractive optical element 13a and the second phase distribution φ2(r, θ) of the second spiral diffractive optical element 14a is shifted in the radial direction relative to the other of the first phase distribution φ1(r, θ) and the second phase distribution φ2(r, θ). The composite phase imparted to the laser beam 3 by the first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a changes. The composite phase is the sum of the first phase distribution φ1(r, θ) and the second phase distribution φ2(r, θ-α), where α is the relative angle. The first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a are arranged close enough to each other that the phase imparted to the laser beam 3 by the first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a can be considered to be the composite phase.

[0176] The change in composite phase changes the ratio between the first intensity of the center spot beam 18 and the second intensity of the ring beam 19. The first intensity of the center spot beam 18 is the maximum intensity of the center spot beam 18. The second intensity of the ring beam 19 is the maximum intensity of the ring beam 19.

[0177] When laser beam 3 is a single-mode laser beam, multiple splits occur in ring beam 19, as shown in Figures 54B, 55B, 56B, 60B, 61B, 62B, 66B, 67B, and 68B. This is because the phase gradient is not constant in the radial direction in first spiral diffractive optical element 13a and second spiral diffractive optical element 14a. By using a multi-mode laser beam as laser beam 3, the occurrence of multiple splits in ring beam 19 can be prevented. The intensity of ring beam 19 in the circumferential direction can be made more uniform.

[0178] The operation of this embodiment will be described in comparison with Embodiment 2. The phase distribution of the first spiral axicon diffractive optical element 13 and the phase distribution of the second spiral axicon diffractive optical element 14 in Embodiment 2 have asymmetric phase distributions within one period in the radial direction (see, for example, FIG. 38 ). Therefore, no matter how the relative angle between the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 is set, the composite phase that the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 impart to the laser beam 3 will not be constant regardless of r and θ (see, for example, FIGS. 39A , 40A , 41A , 42A , 43A , and 44A ). No matter how the relative angle is set, the composite phase generates weak higher-order diffracted light (e.g., ±3rd-order diffracted light and ±5th-order diffracted light). The second intensity of the ring beam 19 cannot be made completely zero, and the ratio of the first intensity of the central spot beam 18 to the second intensity of the ring beam 19 cannot be changed to 1:0.

[0179] In contrast, the phase distributions of the first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a in this embodiment have symmetric phase distributions within one period in the radial direction (see, for example, FIG. 53). Therefore, when the relative angle between the first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a is changed, the composite phase imparted to the laser beam 3 by the first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a may become constant regardless of r and θ (see, for example, FIGS. 57A, 63A, and 68A). When the composite phase becomes constant regardless of r and θ, diffracted light due to the composite phase is completely suppressed. The second intensity of the ring beam 19 can be completely zero, and the ratio between the first intensity of the central spot beam 18 and the second intensity of the ring beam 19 can be changed up to 1:0. The adjustable range of the ratio between the first intensity and the second intensity can be further expanded. The intensity of the central spot beam 18 increases.

[0180] EXAMPLES With reference to FIGS. 52 to 68C and Tables 13 to 15, examples 8 to 10 of this embodiment will be described.

[0181] 52 to 57C and Table 13, the variable optical beam shaper 10 of the eighth embodiment will be described. Table 13 shows the simulation conditions for the eighth embodiment.

[0182]

[0183] As shown in Table 13, Figures 52 and 53, in the eighth embodiment, the first diffractive optical element is a first spiral diffractive optical element 13a having an m1 of 1. The second diffractive optical element is a second spiral diffractive optical element 14a having an m2 of 1. m2 / m1 is 1. a1 is equal to a2, and a2 / a1 is 1. The radial phase distribution of the first spiral diffractive optical element 13a and the radial phase distribution of the second spiral diffractive optical element 14a are stepped triangular wave phase distributions. The number of phase steps s of the first spiral diffractive optical element 13a and the number of phase steps s of the second spiral diffractive optical element 14a are each 16. That is, the first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a are multi-level diffractive optical elements having a number of phase steps s of 16. Δφ1 and Δφ2 are π. The phase period d of each of the first spiral diffractive optical element 13a and the second spiral axicon diffractive optical element ２ The ring diameter D of the ring beam generated by each of the first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a is 851 μm. ０ The other simulation conditions for the eighth example are the same as those for the sixth example of the second embodiment.

[0184] When the relative angle between the first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a about the optical axis O of the diffractive optical system 12 changes, the second phase distribution φ(r, θ) of the second spiral diffractive optical element 14a shifts in the radial direction with respect to the first phase distribution φ(r, θ) of the first spiral diffractive optical element 13a. Therefore, as shown in Figures 54A, 55A, 56A, and 57A, the composite phase that the first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a impart to the laser beam 3 changes. Because the composite phase changes, the ratio between the first intensity of the central spot beam 18 and the second intensity of the ring beam 19 changes, as shown in Figures 54B, 54C, 55B, 55C, 56B, 56C, 57B, and 57C.

[0185] Specifically, when the relative angle is 0 degrees, as shown in Figures 54B and 54C, the entire laser beam 3 is diffracted by the diffractive optical system 12. That is, the diffractive optical system 12 generates multiple ring beams 19 but does not generate the central spot beam 18.

[0186] As the relative angle increases from 0 degrees to 180 degrees, the composite phase changes as shown in Figures 54A, 55A, 56A, and 57A, and diffraction becomes less likely to occur in diffractive optical system 12. Therefore, as shown in Figures 54B, 54C, 55B, 55C, 56B, 56C, 57B, and 57C, the first intensity of central spot beam 18 gradually increases and the second intensity of ring beam 19 gradually decreases.

[0187] When the relative angle is 180 degrees, the composite phase imparted to the laser beam 3 by the first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a is constant regardless of r and θ (see, for example, Figure 57A). Therefore, diffracted light due to the composite phase is completely suppressed. The second intensity of the ring beam 19 can be completely set to zero, and the ratio between the first intensity of the central spot beam 18 and the second intensity of the ring beam 19 can be changed up to 1:0 (see, for example, Figures 57B and 57C). The adjustable range of the ratio between the first intensity and the second intensity can be further expanded. The intensity of the central spot beam 18 increases.

[0188] 58 to 63C and Table 14, the variable optical beam shaper 10 of the ninth embodiment will be described. Table 14 shows the simulation conditions for the ninth embodiment.

[0189]

[0190] As shown in Table 14, Figures 58 and 59, in the ninth embodiment, the radial phase distribution of the first spiral diffractive optical element 13a and the radial phase distribution of the second spiral diffractive optical element 14a are stepped sinusoidal phase distributions. Δφ1 and Δφ2 are 0.7656π. The other simulation conditions for the ninth embodiment are the same as those for the eighth embodiment.

[0191] When the relative angle between the first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a about the optical axis O of the diffractive optical system 12 changes, the second phase distribution φ(r, θ) of the second spiral diffractive optical element 14a shifts in the radial direction with respect to the first phase distribution φ(r, θ) of the first spiral diffractive optical element 13a. Therefore, as shown in Figures 60A, 61A, 62A, and 63A, the composite phase that the first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a impart to the laser beam 3 changes. Because the composite phase changes, the ratio between the first intensity of the central spot beam 18 and the second intensity of the ring beam 19 changes, as shown in Figures 60B, 60C, 61B, 61C, 62B, 62C, 63B, and 63C.

[0192] Specifically, when the relative angle is 0 degrees, as shown in Figures 60B and 60C, the entire laser beam 3 is diffracted by the diffractive optics 12. That is, the diffractive optics 12 generates multiple ring beams 19 but does not generate the central spot beam 18.

[0193] As the relative angle increases from 0 degrees to 180 degrees, the composite phase changes as shown in Figures 60A, 61A, 62A, and 63A, and diffraction becomes less likely to occur in diffractive optical system 12. Therefore, as shown in Figures 60B, 60C, 61B, 61C, 62B, 62C, 63B, and 63C, the first intensity of central spot beam 18 gradually increases and the second intensity of ring beam 19 gradually decreases.

[0194] When the relative angle is 180 degrees, the composite phase imparted to the laser beam 3 by the first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a is constant regardless of r and θ (see, for example, Figure 63A). Therefore, diffracted light due to the composite phase is completely suppressed. The second intensity of the ring beam 19 can be completely set to zero, and the ratio between the first intensity of the central spot beam 18 and the second intensity of the ring beam 19 can be changed up to 1:0 (see, for example, Figures 63B and 63C). The adjustable range of the ratio between the first intensity and the second intensity can be further expanded. The intensity of the central spot beam 18 increases.

[0195] (Tenth Example) In the eighth and ninth examples, m1 and m2 were 1, but even if m1 and m2 are not 1, the ratio between the first intensity of the central spot beam 18 and the second intensity of the ring beam 19 can be changed by changing the relative angle.

[0196] The variable optical beam shaper 10 of the tenth embodiment will be described with reference to Figures 59, 64 to 68C, and Table 15. Table 15 shows the simulation conditions for the tenth embodiment.

[0197]

[0198] The first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a of the tenth embodiment are configured in the same manner as the first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a of the ninth embodiment, but as shown in Table 15 and Fig. 64, in the tenth embodiment, m1 and m2 are 3. The other simulation conditions of the tenth embodiment are the same as those of the ninth embodiment.

[0199] When the relative angle between the first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a about the optical axis O of the diffractive optical system 12 changes, the second phase distribution φ(r, θ) of the second spiral diffractive optical element 14a shifts in the radial direction with respect to the first phase distribution φ(r, θ) of the first spiral diffractive optical element 13a. Therefore, as shown in Figures 65A, 66A, 67A, and 68A, the composite phase that the first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a impart to the laser beam 3 changes. Because the composite phase changes, the ratio between the first intensity of the central spot beam 18 and the second intensity of the ring beam 19 changes, as shown in Figures 65B, 65C, 66B, 66C, 67B, 67C, 68B, and 68C.

[0200] Specifically, when the relative angle is 0 degrees, as shown in Figures 65B and 65C, the entire laser beam 3 is diffracted by the diffractive optical system 12. That is, the diffractive optical system 12 generates multiple ring beams 19 but does not generate the central spot beam 18.

[0201] As the relative angle increases from 0 degrees to 180 degrees, the composite phase changes as shown in Figures 65A, 66A, 67A, and 68A, and diffraction becomes less likely to occur in diffractive optical system 12. Therefore, as shown in Figures 65B, 65C, 66B, 66C, 67B, 67C, 68B, and 68C, the first intensity of central spot beam 18 gradually increases and the second intensity of ring beam 19 gradually decreases.

[0202] When the relative angle is 60 degrees (=180 degrees / m1 or 180 degrees / m2), the composite phase imparted to the laser beam 3 by the first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a is constant regardless of r and θ (see, for example, Figure 68A). Therefore, diffracted light due to the composite phase is completely suppressed. The second intensity of the ring beam 19 can be completely zero, and the ratio between the first intensity of the central spot beam 18 and the second intensity of the ring beam 19 can be changed up to 1:0 (see, for example, Figures 68B and 68C). The adjustable range of the ratio between the first intensity and the second intensity can be further expanded. The intensity of the central spot beam 18 increases.

[0203] 66B, as m1 and m2 increase, the number of split points of ring beam 19 increases. Therefore, as m1 and m2 increase, the period of change in light intensity in the circumferential direction of the ring of ring beam 19 becomes smaller, and the light intensity of ring beam 19 in the circumferential direction of ring beam 19 becomes more uniform. In contrast, as m1 and m2 increase, ring beam 19 takes on a shape that leaves a tail on the outside, and the energy density of ring beam 19 decreases. Therefore, when variable light beam shaper 10 is applied to laser processing apparatus 1, it is preferable that the absolute values ​​of m1 and m2 be greater than 0 and less than or equal to 10.

[0204] 69 to 74C and Table 16, the variable optical beam shaper 10 of the 11th embodiment will be described. Table 16 shows the simulation conditions for the 11th embodiment.

[0205]

[0206] As shown in Table 16, Figures 69 and 70, in Example 11, the radial phase distribution of the first spiral diffractive optical element 13a and the radial phase distribution of the second spiral diffractive optical element 14a are sinusoidal phase distributions. Because the radial phase distribution of the first spiral diffractive optical element 13a and the radial phase distribution of the second spiral diffractive optical element 14a change continuously in the radial direction, the number of phase steps s of the first spiral diffractive optical element 13a and the number of phase steps s of the second spiral diffractive optical element 14a can be considered to be infinite. The other simulation conditions for Example 11 were the same as those for Example 9.

[0207] When the relative angle between the first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a about the optical axis O of the diffractive optical system 12 changes, the second phase distribution φ(r, θ) of the second spiral diffractive optical element 14a shifts in the radial direction with respect to the first phase distribution φ(r, θ) of the first spiral diffractive optical element 13a. Therefore, as shown in Figures 71A, 72A, 73A, and 74A, the composite phase that the first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a impart to the laser beam 3 changes. Because the composite phase changes, the ratio between the first intensity of the central spot beam 18 and the second intensity of the ring beam 19 changes, as shown in Figures 71B, 71C, 72B, 72C, 73B, 73C, 74B, and 74C.

[0208] Specifically, when the relative angle is 0 degrees, as shown in Figures 71B and 71C, the entire laser beam 3 is diffracted by the diffractive optical system 12. That is, the diffractive optical system 12 generates multiple ring beams 19 but does not generate the central spot beam 18.

[0209] As the relative angle increases from 0 degrees to 180 degrees, the composite phase changes as shown in Figures 71A, 72A, 73A, and 74A, and diffraction becomes less likely to occur in diffractive optical system 12. Therefore, as shown in Figures 71B, 71C, 72B, 72C, 73B, 73C, 74B, and 74C, the first intensity of central spot beam 18 gradually increases and the second intensity of ring beam 19 gradually decreases.

[0210] When the relative angle is 180 degrees, the composite phase imparted to the laser beam 3 by the first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a is constant regardless of r and θ (see, for example, Figure 74A). Therefore, diffracted light due to the composite phase is completely suppressed. The second intensity of the ring beam 19 can be completely set to zero, and the ratio between the first intensity of the central spot beam 18 and the second intensity of the ring beam 19 can be changed up to 1:0 (see, for example, Figures 74B and 74C). The adjustable range of the ratio between the first intensity and the second intensity can be further expanded. The intensity of the central spot beam 18 increases.

[0211] 2 and 75 to 80C, a laser processing apparatus 1 and a variable optical beam shaper 10 according to a fifth embodiment will be described. In this embodiment, the variable optical beam shaper 10 includes a driving device 6b instead of the driving device 6.

[0212] 75 , the driving device 6b is connected to, for example, the second spiral axicon diffractive optical element 14. The driving device 6b includes, for example, a holder (not shown) that holds the second spiral axicon diffractive optical element 14, and a linear motion mechanism (not shown) that moves the holder along the optical axis O of the diffractive optical system 12. The driving device 6b moves the second spiral axicon diffractive optical element 14 in the direction of the optical axis O to change the relative distance between the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 in the direction of the optical axis O. Note that the driving device 6b may be connected to the first spiral axicon diffractive optical element 13, and may change the relative distance by moving the first spiral axicon diffractive optical element 13 in the direction of the optical axis O.

[0213] As the relative distance increases, the phase distribution imparted to the laser beam 3 by the first spiral axicon diffractive optical element 13 deteriorates when the laser beam 3 reaches the second spiral axicon diffractive optical element 14. As a result, the phase distribution of the laser beam 3 immediately after passing through the second spiral axicon diffractive optical element 14 also deteriorates. Therefore, as the relative distance increases, the laser beam 3 becomes less likely to be diffracted by the diffractive optical system 12, making it more difficult for the ring beam 19 to be formed. As the relative distance increases, the second intensity of the ring beam 19 decreases and the first intensity of the central spot beam 18 increases. Thus, as the relative distance changes, the ratio between the first intensity of the central spot beam 18 and the second intensity of the ring beam 19 changes.

[0214] 75, in the variable optical beam shaper 10 of the modified example of this embodiment, the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 may be replaced by a first spiral diffractive optical element 13a and a second spiral diffractive optical element 14a (see, for example, FIGS. 52, 53, 58, 59, 64, 69 and 70).

[0215] 75 and 81 to 85C, in a variable optical beam shaper 10 according to a modification of this embodiment, the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 may be replaced by a first axicon diffractive optical element 13b and a second axicon diffractive optical element 14b. The first axicon diffractive optical element 13b and the second axicon diffractive optical element 14b have concentric phase distributions (see, for example, FIGS. 76 and 81) and are optical elements that generate p-th order diffracted beams (p is an integer). The p-th order diffracted beams are, for example, ±1st order diffracted beams. Specifically, the first axicon diffractive optical element 13b has a first phase distribution φ(r, θ) expressed by the above formula (1), and m is zero. The second spiral axicon diffractive optical element 14 has the second phase distribution φ2(r, θ) expressed by the above formula (2), and m2 is zero.

[0216] The first axicon diffractive optical element 13b and the second axicon diffractive optical element 14b may be a binary diffractive optical element, a multi-level diffractive optical element having a phase step number s greater than 2, or a blazed diffractive optical element.

[0217] (Examples) With reference to Figs. 76 to 85C and Table 17, examples 12 and 13 of this embodiment will be described.

[0218] 76 to 80C, a variable optical beam shaper 10 according to a twelfth embodiment will be described. Table 17 shows the simulation conditions for the twelfth embodiment.

[0219]

[0220] As shown in Table 17 and Fig. 76, the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 of the 12th embodiment are the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 of the second embodiment. The simulation conditions for the 12th embodiment are that the ring diameter D of the ring beam generated by each of the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 alone is 1 / 2. ０ The beam diameter of the laser beam 3 and the focal length of the condenser lens 17 are different from the simulation conditions of the second embodiment.

[0221] The first spiral axicon diffractive optical element 13 does not move, and the position of the first spiral axicon diffractive optical element 13 in the direction of the optical axis O of the diffractive optical system 12 does not change. In contrast, the driving device 6b moves the second spiral axicon diffractive optical element 14 in the direction of the optical axis O of the diffractive optical system 12. Therefore, the above-mentioned relative distance changes. As shown in Figures 77A, 78A, 79A, and 80A, as the above-mentioned relative distance increases, the phase distribution of the laser beam 3 immediately after passing through the second spiral axicon diffractive optical element 14 deteriorates.

[0222] As described above, the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 of the twelfth embodiment are the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 of the second embodiment. Therefore, when the relative distance is 0 mm, the twelfth embodiment satisfies equation (22). In other words, when the relative distance is 0 mm, the composite phase imparted to the laser beam 3 by the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 has a phase distribution in which a ring beam 19 is formed but a central spot beam 18 is not formed.

[0223] Thus, when the relative distance is 0 mm and the composite phase has a phase distribution in which ring beam 19 is formed but central spot beam 18 is not formed, as shown in Figures 77B, 77C, 78B, 78C, 79B, 79C, 80B, and 80C, as the relative distance increases, laser beam 3 becomes less likely to be diffracted by diffractive optics 12 and ring beam 19 becomes less likely to be formed. As the relative distance increases, the second intensity of ring beam 19 decreases and the first intensity of central spot beam 18 increases. Thus, by changing the relative distance, the ratio of the first intensity of central spot beam 18 to the second intensity of ring beam 19 changes.

[0224] 81 to 85C and Table 18, the variable optical beam shaper 10 of the 13th embodiment will be described. Table 18 shows the simulation conditions for the 13th embodiment.

[0225]

[0226] 81, in the 13th embodiment, a first axicon diffractive optical element 13b and a second axicon diffractive optical element 14b are used instead of the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 of the 12th embodiment. That is, as shown in Table 18, m1 and m2 are both 0. The other simulation conditions for the 13th embodiment are the same as those for the 12th embodiment.

[0227] The first axicon diffractive optical element 13b does not move, and the position of the first axicon diffractive optical element 13b in the direction of the optical axis O of the diffractive optical system 12 does not change. In contrast, the driving device 6b moves the second axicon diffractive optical element 14b in the direction of the optical axis O of the diffractive optical system 12. Therefore, the above-mentioned relative distance changes. As shown in Figures 82A, 83A, 84A, and 85A, as the above-mentioned relative distance increases, the phase distribution of the laser beam 3 immediately after passing through the second axicon diffractive optical element 14b deteriorates.

[0228] When the relative distance is 0 mm, the thirteenth embodiment satisfies equation (22), similarly to the twelfth embodiment. That is, in the thirteenth embodiment, when the relative distance is 0 mm, the composite phase imparted to the laser beam 3 by the first axicon diffractive optical element 13b and the second axicon diffractive optical element 14b has a phase distribution in which the ring beam 19 is formed but the central spot beam 18 is not formed.

[0229] Thus, when the relative distance is 0 mm and the composite phase has a phase distribution in which ring beam 19 is formed but central spot beam 18 is not formed, as shown in Figures 82B, 82C, 83B, 83C, 84B, 84C, 85B, and 85C, as the relative distance increases, laser beam 3 becomes less likely to be diffracted by diffractive optics 12 and ring beam 19 becomes less likely to be formed. As the relative distance increases, the second intensity of ring beam 19 decreases and the first intensity of central spot beam 18 increases. Thus, by changing the relative distance, the ratio of the first intensity of central spot beam 18 to the second intensity of ring beam 19 changes.

[0230] 86 to 88, a laser processing apparatus 1 and a variable optical beam shaper 10 of embodiment 6 will be described. The laser processing apparatus 1 and the variable optical beam shaper 10 of this embodiment are configured similarly to the laser processing apparatus 1 and the variable optical beam shaper 10 of embodiment 1, but differ in the diffractive optical system 12.

[0231] 86 , in this embodiment, the diffractive optical system 12 further includes a first variable magnification optical system 15. In the direction of the optical axis O of the diffractive optical system 12, the first variable magnification optical system 15 is arranged on the opposite side of the second spiral axicon diffractive optical element 14 from the side of the first spiral axicon diffractive optical element 13. In the direction of the optical axis O of the diffractive optical system 12, the first variable magnification optical system 15 is arranged between the second spiral axicon diffractive optical element 14 and the condenser lens 17.

[0232] 88, the first variable magnification optical system 15 is composed of, for example, three lenses 21, 22, and 23. The lenses 21, 22, and 23 are arranged in this order along the traveling direction of the laser beam 3. The lens 21 is a plano-concave lens with a concave incident surface and has negative refractive power. The lenses 22 and 23 are biconvex lenses and have positive refractive power. The lenses 22 and 23 are movable along the optical axis O of the diffractive optical system 12. The magnification of the first variable magnification optical system 15 changes by moving the lenses 22 and 23 along the optical axis O of the diffractive optical system 12. When the magnification of the first variable magnification optical system 15 changes, the spot diameter Dc of the central spot beam 18 (see FIG. 87) and the ring diameter Dr of the ring beam 19 (see FIG. 87) also change.

[0233] Specifically, when the diffractive optical system 12 includes the first variable magnification optical system 15 having a magnification of X1, the spot diameter Dc (see FIG. 87 ) of the central spot beam 18 is 1 / X1 times the spot diameter Dc of the central spot beam 18 when the diffractive optical system 12 does not include the first variable magnification optical system 15. When the diffractive optical system 12 includes the first variable magnification optical system 15 having a magnification of X1, the ring diameter Dr (see FIG. 87 ) of the ring beam 19 is 1 / X1 times the ring diameter Dr of the ring beam 19 when the diffractive optical system 12 does not include the first variable magnification optical system 15.

[0234] The variable optical beam shaper 10 of this embodiment may include the driving device 6b of embodiment 4 instead of the driving device 6. When the variable optical beam shaper 10 of this embodiment includes the driving device 6b, the diffractive optical system 12 may include the first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a of embodiment 4, or the first axicon diffractive optical element 13b and the second axicon diffractive optical element 14b of embodiment 5, instead of the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14.

[0235] 88 to 91, a laser processing apparatus 1 and a variable optical beam shaper 10 of embodiment 7 will be described. The laser processing apparatus 1 and the variable optical beam shaper 10 of this embodiment are configured similarly to the laser processing apparatus 1 and the variable optical beam shaper 10 of embodiment 6, but differ in the diffractive optical system 12.

[0236] 89 , in the variable optical beam shaper 10 of this embodiment, the diffractive optical system 12 further includes a second variable magnification optical system 16. In the direction of the optical axis O of the diffractive optical system 12, the second variable magnification optical system 16 is arranged on the opposite side of the first spiral axicon diffractive optical element 13 to the side of the second spiral axicon diffractive optical element 14. In the direction of the optical axis O of the diffractive optical system 12, the second variable magnification optical system 16 is arranged between the collimating lens 11 and the first spiral axicon diffractive optical element 13. The first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14 are arranged between the first variable magnification optical system 15 and the second variable magnification optical system 16.

[0237] 91 , the second variable magnification optical system 16 is composed of, for example, three lenses 26, 27, and 28. The lenses 26, 27, and 28 are arranged in this order along the traveling direction of the laser beam 3. The lens 26 is a plano-concave lens with a concave incident surface and has negative refractive power. The lenses 27 and 28 are biconvex lenses and have positive refractive power. The lenses 27 and 28 are movable along the optical axis O of the diffractive optical system 12. The magnification of the second variable magnification optical system 16 changes when the lenses 27 and 28 are moved along the optical axis O of the diffractive optical system 12. When at least one of the magnification of the first variable magnification optical system 15 or the magnification of the second variable magnification optical system 16 changes, the spot diameter Dc of the central spot beam 18 (see FIG. 90 ) and the ring diameter Dr of the ring beam 19 (see FIG. 90 ) change.

[0238] Specifically, when the diffractive optical system 12 includes a first variable magnification optical system 15 having a magnification of X1 and a second variable magnification optical system 16 having a magnification of X2, the spot diameter Dc of the central spot beam 18 (see FIG. 90) is 1 / (X1·X2) times the spot diameter Dc of the central spot beam 18 when the diffractive optical system 12 does not include the first variable magnification optical system 15 or the second variable magnification optical system 16. When the diffractive optical system 12 includes the first variable magnification optical system 15 having a magnification of X1 and the second variable magnification optical system 16 having a magnification of X2, the ring diameter Dr of the ring beam 19 (see FIG. 90) is 1 / X1 times the ring diameter Dr of the ring beam 19 when the diffractive optical system 12 does not include the first variable magnification optical system 15 or the second variable magnification optical system 16. In this embodiment, the spot diameter Dc of the central spot beam 18 and the ring diameter Dr of the ring beam 19 can be changed independently of each other.

[0239] The variable optical beam shaper 10 of this embodiment may include the driving device 6b of embodiment 4 instead of the driving device 6. When the variable optical beam shaper 10 of this embodiment includes the driving device 6b, the diffractive optical system 12 may include the first spiral diffractive optical element 13a and the second spiral diffractive optical element 14a of embodiment 4, or the first axicon diffractive optical element 13b and the second axicon diffractive optical element 14b of embodiment 5, instead of the first spiral axicon diffractive optical element 13 and the second spiral axicon diffractive optical element 14.

[0240] In the variable optical beam shapers 10 of the first to seventh embodiments and their modified examples, the focusing function of the focusing lens 17 may be imparted to at least one of the first spiral axicon diffractive optical element 13 or the second spiral axicon diffractive optical element 14, or at least one of the first axicon diffractive optical element 13b or the second axicon diffractive optical element 14b, and the focusing lens 17 may be omitted. Furthermore, the variable optical beam shapers 10 of the first to seventh embodiments and their modified examples may be applied to a device different from the laser processing device 1 (for example, a laser measurement device, etc.).

[0241] The presently disclosed embodiments 1 to 7 and their modifications are illustrative in all respects and should not be considered limiting. Furthermore, unless there is a contradiction, at least two of the presently disclosed embodiments 1 to 7 and their modifications may be combined. The scope of the present disclosure is defined by the claims, not the above-described embodiments, and is intended to include meanings equivalent to the claims and all modifications within the scope of the claims.

[0242] 1 laser processing apparatus, 2 laser light source, 3 laser beam, 3a first beam, 3b second beam, 4 optical fiber, 5 optical head, 5a housing, 5b window, 6, 6b drive device, 7 stage, 7a mounting surface, 8 stage drive device, 10 variable optical beam shaper, 11 collimating lens, 12 diffractive optical system, 13 first spiral axicon diffractive optical element, 13a first spiral diffractive optical element, 13b first axicon diffractive optical element, 14 second spiral axicon diffractive optical element, 14a second spiral diffractive optical element, 14b second axicon diffractive optical element, 15 first variable magnification optical system, 16 second variable magnification optical system, 17 condensing lens, 18 central spot beam, 19 ring beam, 21, 22, 23, 26, 27, 28 lens, O optical axis, W work.

Claims

1. A diffractive optical system including a first diffractive optical element and a second diffractive optical element, wherein the first diffractive optical element and the second diffractive optical element can generate a first beam and a second beam having different diffraction orders from a laser beam incident on the diffractive optical system, and the diffractive optical system can generate a central spot beam and a ring beam around the central spot beam from the first beam and the second beam, respectively; one of the first diffractive optical element and the second diffractive optical element is configured to be rotatable about the optical axis of the diffractive optical system relative to the other of the first diffractive optical element and the second diffractive optical element; the first diffractive optical element and the second diffractive optical element are a first spiral axicon diffractive optical element and a second spiral axicon diffractive optical element, respectively, or a first spiral diffractive optical element and a second spiral diffractive optical element, each having a periodic phase distribution in a radial direction, and the periodic phase distribution is symmetric within one period of the periodic phase distribution; A variable optical beam shaper, wherein the periodic phase distribution changes in a step-like manner with a number of stages greater than two in the radial direction, or the phase changes continuously in the radial direction.

2. The first and second diffractive optical elements are the first and second spiral axicon diffractive optical elements, and the first spiral axicon diffractive optical element has a first phase distribution φ1(r, θ) expressed by the following formula (1), and the second spiral axicon diffractive optical element has a second phase distribution φ2(r, θ) expressed by the following formula (2), φ1(r, θ)=a1·r+m1·θ+ψi1 ... (1) φ2(r, θ)=a2·r+m2·θ+ψi2 ... (2) wherein r is a radial distance in polar coordinates, said r is a physical quantity having a dimension of length, θ is a deflection angle of said polar coordinates, a1 and a2 are each coefficients having a dimension of the reciprocal of length and are real numbers excluding zero, a2 / a1 is 0.97 or more and 1.03 or less, m1 and m2 are each real numbers excluding zero, m2 / m1 is 0.95 or more and 1.05 or less, and ψi1 and ψi2 are initial phases and are arbitrary real numbers.

3. A variable optical beam shaper as described in claim 1 or claim 2, wherein the first diffractive optical element and the second diffractive optical element are the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element, the first spiral axicon diffractive optical element is a first binary diffractive optical element, and the second spiral axicon diffractive optical element is a second binary diffractive optical element.

4. The variable optical beam shaper of claim 3, wherein the first binary diffractive optical element has a first phase step Δφ1, the second binary diffractive optical element has a second phase step Δφ2, and the diffractive optical system satisfies any of the following conditional expressions (3) to (6): 0.9π≦mod 2π(Δφ1)≦1.1π... (3) 0.9π≦mod 2π(Δφ2)≦1.1π... (4) 0.9π≦mod 2π(Δφ1 + Δφ2)≦1.1π... (5) 0.9π≦|mod 2π(Δφ1) - mod 2π(Δφ2)|≦1.1π... (6), where mod 2π( ) is a modulo operation of 2π.

5. The variable optical beam shaper of claim 3, wherein the first binary diffractive optical element has a first phase step Δφ1, the second binary diffractive optical element has a second phase step Δφ2, and the diffractive optical system satisfies the following conditional expressions (7) and (8): 0.9π≦mod 2π(Δφ1)+mod 2π(Δφ2)≦3.3π... (7) 0.9π≦|mod 2π(Δφ1)-mod 2π(Δφ2)|≦1.1π... (8), where mod 2π( ) is a modulo 2π operation.

6. The variable optical beam shaper according to claim 1 or 2, wherein the first diffractive optical element and the second diffractive optical element are the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element, the first spiral axicon diffractive optical element is a first multi-level diffractive optical element, and the number of phase steps of the first multi-level diffractive optical element is a natural number greater than 2, and the second spiral axicon diffractive optical element is a second multi-level diffractive optical element having the number of phase steps.

7. The variable optical beam shaper of claim 6, wherein the first multi-level diffractive optical element has a first maximum phase step Δφ1, the second multi-level diffractive optical element has a second maximum phase step Δφ2, and the diffractive optical system satisfies the following conditional expressions (9) and (10), or satisfies the following conditional expression (11): 0.9π≦mod 2π(Δφ1)≦1.1π... (9) 0.9π≦mod 2π(Δφ2)≦1.1π... (10) 0.9×2π(s-1) / s≦mod 2π(Δφ1+Δφ2)≦1.1×2π(s-1) / s... (11), where s is the number of phase steps, and mod 2π( ) is a modulo 2π operation.

8. A variable optical beam shaper as described in claim 1 or claim 2, wherein the first diffractive optical element and the second diffractive optical element are the first spiral axicon diffractive optical element and the second spiral axicon diffractive optical element, the first spiral axicon diffractive optical element is a first blazed diffractive optical element, and the second spiral axicon diffractive optical element is a second blazed diffractive optical element.

9. The variable optical beam shaper of claim 8, wherein the first blazed diffractive optical element has a first maximum phase step Δφ1, the second blazed diffractive optical element has a second maximum phase step Δφ2, and the diffractive optical system satisfies the following conditional expressions (12) and (13): 0.9π≦mod 2π(Δφ1)≦1.1π... (12) 0.9π≦mod 2π(Δφ2)≦1.1π... (13), where mod 2π( ) is a modulo 2π operation.

10. The first and second diffractive optical elements are the first and second spiral diffractive optical elements, and the first spiral diffractive optical element has a first phase distribution φ1(r, θ) expressed by the following formula (14), and the second spiral diffractive optical element has a second phase distribution φ2(r, θ) expressed by the following formula (15): φ1(r, θ)=f1(a1·r+m1·θ) ... (14) φ2(r, θ)=f2(a2·r+m2·θ) ... (15) where r is a distance in the radial direction of polar coordinates, said r is a physical quantity having a dimension of length, θ is an argument of said polar coordinates, a1 and a2 are each coefficients having a dimension of the reciprocal of length and are real numbers excluding zero, a2 / a1 is 0.97 or more and 1.03 or less, m1 and m2 are each real numbers excluding zero, m2 / m1 is 0.95 or more and 1.05 or less, the function f1(a1·r+m1·θ) satisfies the following formulas (16) and (17), and the function f2(a2·r+m2·θ) satisfies the following formulas (18) and (19): f1(a1·r+m1·θ)=f1(a1·(r+2π / a1)+m1·θ) (16) f1(a1·r+m1·θ)+f1(a1·(r+π / a1)+m1·θ)=first constant... (17) f2(a2·r+m2·θ)=f2(a2·(r+2π / a2)+m2·θ)... (18) f2(a2·r+m2·θ)+f2(a2·(r+π / a2)+m2·θ)=second constant... (19) The variable optical beam shaper of claim 1, wherein the first constant and the second constant are constants independent of r and θ, respectively.

11. A variable optical beam shaper as described in claim 1 or claim 10, wherein the first diffractive optical element and the second diffractive optical element are the first spiral diffractive optical element and the second spiral diffractive optical element, respectively, having the periodic phase distribution in the radial direction, and the periodic phase distribution is a stepped triangular wave phase distribution or a continuously changing triangular wave phase distribution.

12. A variable optical beam shaper according to claim 11, wherein the difference between the maximum value of the phase and the minimum value of the phase in one period of the phase distribution is not less than 0.9π and not more than 1.1π.

13. A variable optical beam shaper as described in claim 1 or claim 10, wherein the first diffractive optical element and the second diffractive optical element are the first spiral diffractive optical element and the second spiral diffractive optical element, respectively, having the periodic phase distribution in the radial direction, and the periodic phase distribution is a stepped sine wave phase distribution or a continuously changing sine wave phase distribution.

14. A variable optical beam shaper according to claim 13, wherein the difference between the maximum value of the phase and the minimum value of the phase in one period of the phase distribution is equal to or greater than 0.68904π and equal to or less than 0.84216π.

15. A variable light beam shaper as described in any one of claims 1 to 14, further comprising a first variable magnification optical system, wherein the first diffractive optical element and the second diffractive optical element are arranged in this order in the direction of propagation of the laser beam, and the first variable magnification optical system is arranged on the opposite side of the second diffractive optical element to the first diffractive optical element in the direction of the optical axis of the diffractive optical system.

16. A variable optical beam shaper as described in claim 15, further comprising a second variable magnification optical system, wherein the second variable magnification optical system is arranged on the opposite side of the first diffractive optical element from the side of the second diffractive optical element in the direction of the optical axis.

17. A diffractive optical system including a first diffractive optical element and a second diffractive optical element, wherein the first diffractive optical element and the second diffractive optical element can generate a first beam and a second beam having different diffraction orders from a laser beam incident on the diffractive optical system, and the diffractive optical system can generate a central spot beam and a ring beam around the central spot beam from the first beam and the second beam, respectively; one of the first diffractive optical element and the second diffractive optical element is configured to be movable in the direction of the optical axis of the diffractive optical system relative to the other of the first diffractive optical element and the second diffractive optical element; and the first diffractive optical element and the second diffractive optical element are a first spiral axicon diffractive optical element and a second spiral axicon diffractive optical element, or a first spiral diffractive optical element and a second spiral diffractive optical element each having a periodic phase distribution in the radial direction, or a first axicon diffractive optical element and a second axicon diffractive optical element, The periodic phase distribution is symmetric within one period of the periodic phase distribution, and the periodic phase distribution changes in a step-like manner with a number of steps greater than two in the radial direction, or the phase changes continuously in the radial direction.

18. A variable optical beam shaper as described in claim 17, further comprising a first variable magnification optical system, wherein the first diffractive optical element and the second diffractive optical element are arranged in this order in the direction of propagation of the laser beam, and the first variable magnification optical system is arranged on the opposite side of the second diffractive optical element from the side of the first diffractive optical element in the direction of the optical axis.

19. A variable optical beam shaper as described in claim 18, further comprising a second variable magnification optical system, wherein in the direction of the optical axis, the second variable magnification optical system is arranged on the opposite side of the first diffractive optical element from the side of the second diffractive optical element.

20. A laser processing device comprising the variable optical beam shaper according to any one of claims 1 to 19.

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