Data creation device, data creation method, and data creation program

Abstract

This improves the efficiency of generating optical pulses for laser processing, which are formed using a spatial light modulator. [Solution] The data creation device 1 is a device for creating data to control an SLM24 that shapes light pulses for laser processing, and comprises: a waveform setting unit 11 which sets information on a plurality of different time-intensity waveforms, each containing a plurality of light pulses; a spectrum design unit 12 which generates a plurality of sets of intensity spectral functions and phase spectral functions based on each of the plurality of time-intensity waveforms; a data generation unit 15 which creates a plurality of data based on each of the plurality of sets of intensity spectral functions and phase spectral functions; and a data determination unit 16 which calculates the generation efficiency of each of the plurality of time-intensity waveforms in the SLM24 based on each of the plurality of data, and determines data to control the SLM24 from the plurality of data based on the generation efficiency.

Description

[Technical Field]

[0001] This disclosure relates to a data creation device, a data creation method, and a data creation program. [Background technology]

[0002] Conventionally, a technique for shaping optical pulses for laser processing using a spatial light modulator (SLM) is known. An SLM shapes the time waveform of an optical pulse by modulating its intensity spectrum and phase spectrum. By using a multi-pulse generated by modulating a single pulse with an SLM for laser processing, the processing efficiency of laser processing can be improved (see, for example, Non-Patent Documents 1 and 2). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Du, Kun, et al., “Controllable photon energy deposition efficiency in laser processing of fused silica by temporally shaped femtosecond pulse: Experimental and theoretical study”, Optics and Laser Technology, 128 (2020):106265. [Non-Patent Document 2] Jiang, Lan, et al., "High-throughput rear-surface drilling of microchannels in glass based on electron dynamics control using femtosecondpulse trains." (2012): 2781. [Overview of the project] [Problems that the invention aims to solve]

[0004] In the technique of shaping optical pulses for laser processing using the SLM described above, energy loss of the optical pulse occurs during shaping. Therefore, in order to improve the energy utilization efficiency in laser processing, it is desirable to have a high efficiency in generating optical pulses after shaping.

[0005] Therefore, the data creation apparatus, data creation method, and data creation program according to one aspect of this disclosure aim to improve the generation efficiency of optical pulses for laser processing formed using an SLM. [Means for solving the problem]

[0006] The gist of this disclosure is as follows:

[0007] [1] A data creation device for creating data to control a spatial light modulator for shaping light pulses for laser processing, comprising: a waveform setting unit that sets information on a plurality of different time-intensity waveforms, each containing a plurality of light pulses; a spectrum design unit that generates each of a plurality of sets of intensity spectral functions and phase spectral functions based on each of the plurality of time-intensity waveforms; a data generation unit that creates each of a plurality of data based on each of the plurality of sets of intensity spectral functions and phase spectral functions; and a data determination unit that calculates the generation efficiency of each of the plurality of time-intensity waveforms in the spatial light modulator based on each of the plurality of data, and determines data to control the spatial light modulator from the plurality of data based on the generation efficiency.

[0008] The inventors' research has revealed the following: When a single pulse is shaped into multiple optical pulses with uniform peak values ​​using a spatial light modulator and used for laser processing, the processing results with the same time-intensity waveform have low reproducibility and show different trends depending on the number of optical pulses. Therefore, the inventors furthered their research and obtained the following finding: Among multiple time-intensity waveforms, each containing multiple optical pulses and having varying peak values ​​for each of the contained optical pulses, there exists a time-intensity waveform that has a higher generation efficiency in the spatial light modulator compared to a time-intensity waveform containing multiple optical pulses with uniform peak values. In the data creation device described above, multiple data sets are created based on each of the multiple time-intensity waveforms, and data for controlling the spatial light modulator is determined from the created data sets based on the generation efficiency in the spatial light modulator for each time-intensity waveform corresponding to each data set. This makes it possible to shape the optical pulse to approach the time-intensity waveform corresponding to the desired generation efficiency. Therefore, the generation efficiency of optical pulses for laser processing can be improved.

[0009] [2] The data determination unit determines the data for controlling the spatial light modulator that has the highest generation efficiency from among the plurality of data, as described in [1]. This makes it possible to shape the light pulse to approach the time intensity waveform with the highest generation efficiency. Therefore, the generation efficiency of light pulses for laser processing can be further improved.

[0010] [3] The data creation device according to either [1] or [2], wherein the minimum peak value of the plurality of light pulses is 80% or more of the maximum peak value of the plurality of light pulses. This improves the accuracy of calculating the intensity spectral function and phase spectral function to approach the time-intensity waveform set in the waveform setting unit. Furthermore, processing results almost the same as when the respective peak values ​​are uniform can be obtained.

[0011] [4] The minimum peak value is a value that is 80% or more and 95% or less of the maximum peak value, for the data creation device according to any one of [1] to [3]. By the minimum peak value being 80% or more of the maximum peak value, the accuracy of calculating the intensity spectrum function and the phase spectrum function for approaching the time-intensity waveform set in the waveform setting unit is improved. Also, it is possible to obtain a processing result that is almost the same as when each peak value is uniform. By the minimum peak value being 95% or less of the maximum peak value, in the data setting unit, it is possible to set a time-intensity waveform in which the peak values of a plurality of optical pulses vary more greatly. Therefore, the possibility of shaping the optical pulses so as to approach a time-intensity waveform with higher generation efficiency increases, and thus the generation efficiency of the optical pulses for laser processing can be further improved.

[0012] [5] The waveform setting unit sets information regarding the time-intensity waveform including 50 or fewer optical pulses, for the data creation device according to any one of [1] to [4]. Thereby, it is possible to shape the optical pulses so as to approach a time-intensity waveform suitable for laser processing.

[0013] [6] The waveform setting unit sets information regarding the time-intensity waveform including 20 or fewer optical pulses, for the data creation device according to any one of [1] to [5]. Thereby, it is possible to shape the optical pulses so as to approach a time-intensity waveform suitable for laser processing.

[0014] [7] The waveform setting unit sets information regarding the time-intensity waveform including the plurality of optical pulses with a pulse interval of 10 fs or more and 100 ps or less, for the data creation device according to any one of [1] to [6]. Thereby, it is possible to shape the optical pulses so as to approach a time-intensity waveform suitable for laser processing.

[0015] [8]A method for creating data for controlling a spatial light modulator that shapes optical pulses for laser processing, the method comprising: a waveform setting step of setting information regarding a plurality of different temporal intensity waveforms each including a plurality of optical pulses; a spectrum design step of generating each of a plurality of sets of intensity spectrum functions and phase spectrum functions based on each of the plurality of temporal intensity waveforms; a data generation step of creating each of a plurality of data based on each of the plurality of sets of intensity spectrum functions and phase spectrum functions; a data determination step of calculating the generation efficiency of each of the plurality of temporal intensity waveforms in the spatial light modulator based on each of the plurality of data, and determining data for controlling the spatial light modulator from among the plurality of data based on the generation efficiency.

[0016] In this data creation method, each of a plurality of data created based on each of a plurality of different temporal intensity waveforms is created, and data for controlling the spatial light modulator is determined from among the created plurality of data based on the generation efficiency of each temporal intensity waveform corresponding to each data in the spatial light modulator. Thereby, the optical pulses can be shaped so as to approach the temporal intensity waveform corresponding to a desired generation efficiency. Therefore, the generation efficiency of the optical pulses for laser processing can be improved.

[0017] [9] A program for creating data to control a spatial light modulator for shaping light pulses for laser processing, comprising: a waveform setting step of setting information about a plurality of different time-intensity waveforms, each containing a plurality of light pulses; a spectrum design step of generating each of a plurality of sets of intensity spectral functions and phase spectral functions based on each of the plurality of time-intensity waveforms; a data generation step of creating each of a plurality of data based on each of the plurality of sets of intensity spectral functions and phase spectral functions; and a data determination step of calculating the generation efficiency of each of the plurality of time-intensity waveforms in the spatial light modulator based on each of the plurality of data, and determining data to control the spatial light modulator from the plurality of data based on the generation efficiency.

[0018] This data creation program generates multiple data sets based on several different time-intensity waveforms. From these multiple data sets, it determines the data to control the spatial light modulator based on the generation efficiency of each time-intensity waveform corresponding to each data set. This allows the optical pulse to be shaped to approach the time-intensity waveform corresponding to the desired generation efficiency. Therefore, the generation efficiency of optical pulses for laser processing can be improved. [Effects of the Invention]

[0019] According to one aspect of the data creation apparatus, data creation method, and data creation program of this disclosure, it is possible to improve the generation efficiency of optical pulses for laser processing formed using an SLM. [Brief explanation of the drawing]

[0020] [Figure 1] Figure 1 is a schematic diagram showing the configuration of a data creation device according to one embodiment of the present disclosure. [Figure 2] Figure 2 shows the configuration of the optical system provided by the optical control device. [Figure 3] Figure 3 shows the modulation plane of the SLM. [Figure 4] Figure 4(a) shows, as an example, the spectral waveform (spectral phase and spectral intensity) of a single-pulse input light, and Figure 4(b) shows the time-intensity waveform of the same input light. [Figure 5] Figure 5(a) shows, as an example, the spectral waveform (spectral phase and spectral intensity) of the output light when rectangular wave-shaped phase spectral modulation is applied to an SLM, and Figure 5(b) shows the time intensity waveform of the same output light. [Figure 6] Figure 6 is a schematic diagram showing an example of the hardware configuration of a data creation device. [Figure 7] Figure 7 shows examples of time-intensity waveforms set in the waveform setting unit. [Figure 8] Figure 8 shows an example of the calculation procedure for a phase spectrum using the iterative Fourier method. [Figure 9] Figure 9 is a flowchart showing the data creation method. [Figure 10] Figure 10 shows the generation efficiency in the SLM for each number of pulses, corresponding to the time-intensity waveform set in the waveform setting unit. [Figure 11] Figure 11(a) shows the spectral waveform corresponding to data point P1 in Figure 10 when there are 9 pulses, and Figure 11(b) shows the time intensity waveform corresponding to the spectral waveform. [Figure 12] Figure 12(a) shows the spectral waveform corresponding to data point P2 in Figure 10 when there are 9 pulses, and Figure 12(b) shows the time intensity waveform corresponding to the spectral waveform. [Figure 13] Figure 13(a) shows the spectral waveform of the output light as an alternative example, and Figure 13(b) shows the time-intensity waveform corresponding to that spectral waveform. [Figure 14] Figure 14(a) shows the spectral waveform of the output light as an alternative example, and Figure 14(b) shows the time-intensity waveform corresponding to the spectral waveform. [Modes for carrying out the invention]

[0021] Hereinafter, with reference to the drawings, embodiments of a data creation device, data creation method, and data creation program according to one aspect of this disclosure will be described in detail. In each figure, the same elements or corresponding elements are denoted by the same reference numerals, and redundant explanations may be omitted.

[0022] Figure 1 is a schematic diagram showing the configuration of a data creation device 1 according to one embodiment of the present disclosure. Figure 2 is a diagram showing the configuration of the optical system 20 provided by the optical control device 2. The data creation device 1 constitutes, for example, a part of the optical control device 2. As shown in Figure 1, the data creation device 1 includes a waveform setting unit 11, a spectrum design unit 12, a data generation unit 15, and a data determination unit 16. The optical control device 2 also includes an optical system 20 and a light source 21. As shown in Figure 2, the optical system 20 includes a diffraction grating 22, a lens 23, an SLM 24, a lens 25, and a diffraction grating 26. The optical control device 2 generates output light Ld, which includes multiple optical pulses, from an input light La, which is a single optical pulse. The data creation device 1 creates data for the optical control device 2 to generate output light Ld from the input light La. The output light Ld is used for laser processing.

[0023] The light source 21 outputs input light La that is input to the optical system 20. The light source 21 is a laser light source such as a solid-state laser light source, a gas laser light source, a liquid laser light source, a semiconductor laser light source, or a fiber laser light source, and the input light La is, for example, coherent pulsed light. The optical system 20 has an SLM 24 and receives a control signal SC from the data creation device 1 to control each pixel of the SLM 24. The optical system 20 converts the input light La from the light source 21 into output light Ld. The control signal SC includes a modulation pattern for the SLM 24 that converts the input light La into output light Ld. The modulation pattern is represented by data for controlling the SLM 24, and is data output to a file that represents the intensity of the complex amplitude distribution or the intensity of the phase distribution. The modulation pattern is, for example, a computer-generated hologram (CGH).

[0024] The diffraction grating 22 is the spectroscopic element in this embodiment and is optically coupled to the light source 21. The SLM 24 is optically coupled to the diffraction grating 22 via the lens 23. The diffraction grating 22 spectrally separates the input light La into its wavelength components. Note that other optical components such as a prism may be used instead of the diffraction grating 22 as the spectroscopic element. Furthermore, the spectroscopic element may be reflective or transmissive. The input light La is incident obliquely on the diffraction grating 22 and spectrally separated into multiple wavelength components. The light Lb containing these multiple wavelength components is focused by the lens 23 for each wavelength component and imaged onto the modulation plane of the SLM 24. The lens 23 may be a convex lens made of a light-transmitting material, or a concave mirror having a concave light-reflecting surface.

[0025] The SLM24 simultaneously performs phase modulation and intensity modulation of optical light Lb to generate output optical light Ld containing multiple optical pulses by shaping input optical light La, which is a single optical pulse. The SLM24 may also perform intensity modulation only. The SLM24 is, for example, a phase-modulated type. In one embodiment, the SLM24 is an LCOS (Liquid crystal on silicon) type. Alternatively, the SLM24 may be an intensity-modulated SLM such as a digital micromirror device (DMD). Furthermore, the SLM24 may be reflective or transmissive. Figure 3 shows the modulation surface 27 of the SLM24. As shown in Figure 3, the modulation surface 27 has multiple modulation regions 27a arranged along a certain direction A, and each modulation region 27a extends in a direction B that intersects direction A. Direction A is the spectral direction by the diffraction grating 22. This modulation surface 27 acts as a Fourier transform surface, and the corresponding wavelength components after spectral separation are incident on each of the multiple modulation regions 27a. In each modulation region 27a, the SLM24 modulates the phase and intensity of each incident wavelength component independently of other wavelength components. Since the SLM24 in this embodiment is a phase-modulation type, intensity modulation is achieved by a phase pattern (phase image) presented on the modulation surface 27.

[0026] Each wavelength component of the modulated light Lc, modulated by the SLM24, is focused to a single point on the diffraction grating 26 by the lens 25. At this time, the lens 25 functions as a focusing optical system that focuses the modulated light Lc. The lens 25 may be a convex lens made of a light-transmitting material, or it may be a concave mirror having a concave light-reflecting surface. The diffraction grating 26 functions as a multiplexing optical system, combining each wavelength component after modulation. In other words, through the lens 25 and diffraction grating 26, the multiple wavelength components of the modulated light Lc are focused and combined to form the output light Ld.

[0027] The region in front of lens 25 (spectral domain) and the region behind diffraction grating 26 (time domain) are in a Fourier transform relationship with each other, and phase modulation and intensity modulation in the spectral domain affect the time-intensity waveform in the time domain. Therefore, the output light Ld will have a desired time-intensity waveform that is different from the input light La, depending on the modulation pattern of SLM24. Here, Figure 4(a) shows the spectral waveform (spectral phase G11 and spectral intensity G12) of a single-pulse input light La as an example, and Figure 4(b) shows the time-intensity waveform of the input light La. Also, Figure 5(a) shows the spectral waveform (spectral phase G21 and spectral intensity G22) of the output light Ld when rectangular wave-shaped phase spectral modulation is applied in SLM24 as an example, and Figure 5(b) shows the time-intensity waveform of the output light Ld. In Figures 4(a) and 5(a), the horizontal axis represents wavelength (nm), the left vertical axis represents the intensity value of the intensity spectrum (in arbitrary units), and the right vertical axis represents the phase value of the phase spectrum (rad). In Figures 4(b) and 5(b), the horizontal axis represents time (femtoseconds), and the vertical axis represents light intensity (in arbitrary units). In this example, by applying a rectangular wave-shaped phase spectrum waveform to the output light Ld, the single pulse of the input light La is converted into a double pulse with higher-order light as the output light Ld. Note that the spectra and waveforms shown in Figures 4 and 5 are just examples, and the time-intensity waveform of the output light Ld can be shaped into various forms by various combinations of phase spectra and intensity spectra.

[0028] Refer to Figure 1 again. The data creation device 1 is a computer with a processor, such as a personal computer, a smart device such as a smartphone or tablet terminal, or a cloud server. The data creation device 1 is electrically connected to the SLM 24 and calculates a phase modulation pattern to bring the time intensity waveform of the output light Ld closer to a desired waveform, and provides the SLM 24 with a control signal SC including the phase modulation pattern. In this embodiment, the data creation device 1 causes the SLM 24 to present a phase pattern that includes a phase modulation phase pattern that gives the output light Ld a phase spectrum for obtaining the desired waveform, and an intensity modulation phase pattern that gives the output light Ld an intensity spectrum for obtaining the desired waveform. To this end, the data creation device 1 has a waveform setting unit 11, a spectrum design unit 12, a data generation unit 15, and a data determination unit 16. The spectrum design unit 12 includes a phase spectrum design unit 13 and an intensity spectrum design unit 14. In other words, the computer processor provided in the data creation device 1 implements the functions of the waveform setting unit 11, the phase spectrum design unit 13, the intensity spectrum design unit 14, the data generation unit 15, and the data determination unit 16. Each of these functions may be implemented by the same processor or by different processors.

[0029] Figure 6 is a schematic diagram showing an example of the hardware configuration of the data creation device 1. As shown in Figure 6, the data creation device 1 may be physically configured as a normal computer, including a processor (CPU) 101, main memory such as ROM 102 and RAM 103, input devices 104 such as a keyboard, mouse and touchscreen, output devices 105 such as a display (including a touchscreen), a communication module 106 such as a network card for sending and receiving data with other devices, and auxiliary storage devices 107 such as a hard disk.

[0030] The computer processor 101 can implement each of the above functions (waveform setting unit 11, phase spectrum design unit 13, intensity spectrum design unit 14, data generation unit 15, and data determination unit 16) through a data creation program. Therefore, the data creation program causes the computer processor 101 to operate as the waveform setting unit 11, phase spectrum design unit 13, intensity spectrum design unit 14, data generation unit 15, and data determination unit 16 in the data creation device 1. The data creation program is stored in a storage device (storage medium) inside or outside the computer, such as an auxiliary storage device 107. The storage device may be a non-temporary storage medium. Examples of storage media include flexible disks, CDs, DVDs, ROMs, semiconductor memory, and cloud servers.

[0031] The waveform setting unit 11 receives input information regarding a desired time-intensity waveform of the output light Ld. This information includes setting conditions such as pulse width, number of pulses, and pulse interval. Based on the information regarding the desired time-intensity waveform, the waveform setting unit 11 randomly sets each of several different time-intensity waveforms that satisfy the setting conditions and each contains multiple light pulses as the desired time-intensity waveform. Alternatively, the waveform setting unit 11 may accept input from the operator and set each of several different time-intensity waveforms that satisfy the setting conditions and each contains multiple light pulses as the desired time-intensity waveform.

[0032] Figures 7(a) to 7(c) show examples of time-intensity waveforms set in the waveform setting unit 11. In Figures 7(a) to 7(c), the horizontal axis represents time (arbitrary unit), and the vertical axis represents light intensity (arbitrary unit). The time-intensity waveforms shown in Figures 7(a) to 7(c) each contain five light pulses and have a minimum peak value V valley The maximum peak value is V peakThis is an example when a time-intensity waveform with a value of 80% or more is randomly set. As shown in FIGS. 7(a) and 7(b), a plurality of different time-intensity waveforms in which the peak values of a plurality of optical pulses vary are set. As shown in FIG. 7(c), the minimum peak value V valley and the maximum peak value V peak may be equal (that is, the peak values of the plurality of pulses included in the time-intensity waveform may be uniform). The lower limit value of the minimum peak value V valley is not limited to 80% of the value of the maximum peak value V peak . Also, the minimum peak value V valley may be, for example, a value of 80% or more and 95% or less of the maximum peak value V peak , and the upper limit value of the minimum peak value V valley is not limited to 95% of the value of the maximum peak value V peak . The number of pulses having the minimum peak value V valley and the maximum peak value V peak may be one or more. The number of pulses included in the time-intensity waveform is not limited to 5, and may be, for example, 50 or less or 20 or less. Also, the pulse interval of the plurality of optical pulses included in the time-intensity waveform may be, for example, 10 fs or more and 100 ps or less. Note that FIGS. 7(a) to 7(c) are examples when the pulse intervals are equally spaced.

[0033] Information regarding the desired time-intensity waveform is given to the phase spectrum design unit 13 and the intensity spectrum design unit 14. The phase spectrum design unit 13 calculates the phase spectrum of the output light Ld suitable for realizing the given desired time-intensity waveform. The intensity spectrum design unit 14 calculates the intensity spectrum of the output light Ld suitable for realizing the given desired time-intensity waveform. The data generation unit 15 calculates a phase modulation pattern (for example, a computer-generated hologram) for giving the phase spectrum obtained in the phase spectrum design unit 13 and the intensity spectrum obtained in the intensity spectrum design unit 14 to the output light Ld. Then, a control signal SC including the calculated phase modulation pattern is provided to the SLM 24, and the SLM 24 is controlled based on the control signal SC.

[0034] Here, we will describe in detail the method for calculating the phase spectrum and intensity spectrum corresponding to a desired time-intensity waveform. The desired time-intensity waveform is expressed as a function in the time domain, and the phase spectrum and intensity spectrum are expressed as functions in the frequency domain. Therefore, the phase spectrum and intensity spectrum corresponding to a desired time-intensity waveform are obtained by an iterative Fourier transform based on the desired time-intensity waveform. In the method described below, the phase spectrum and intensity spectrum are calculated using the iterative Fourier transform method. For this reason, as shown in Figure 1, the phase spectrum design unit 13 has an iterative Fourier transform unit 13a, and the intensity spectrum design unit 14 has an iterative Fourier transform unit 14a.

[0035] Figure 8 shows an example of the calculation procedure for the phase spectrum using the iterative Fourier method in the iterative Fourier transform section 13a. First, the initial intensity spectral function A0(ω) and the phase spectral function Ψ are functions of frequency ω. n=0 Prepare (ω) (process number (1) in the figure). In one example, these are the intensity spectral function A0(ω) and the phase spectral function Ψ. n=0 (ω) represents the intensity spectrum and phase spectrum of the input light La, respectively. Next, the intensity spectral function A0(ω) and the phase spectral function Ψ n Prepare a frequency-domain waveform function (a) that includes (ω) (process number (2) in the figure).

number

[0036] Next, a Fourier transform from the frequency domain to the time domain is performed on the above function (a) (arrow A1 in the figure). This gives the time intensity waveform function b n The frequency domain waveform function (b) including (t) is obtained (process number (3) in the figure).

number

[0037] Next, the time-intensity waveform function b included in the above function (b) n Replace (t) with Target0(t) based on the desired waveform (process numbers (4) and (5) in the figure).

number

number

[0038] Next, an inverse Fourier transform from the time domain to the frequency domain is performed on the above function (d) (arrow A2 in the figure). This gives the intensity spectral function B n (ω) and phase spectral function Ψ n The frequency-domain waveform function (e) containing (ω) is obtained (process number (6) in the figure).

number

[0039] Next, the intensity spectral function B included in the above function (e) n To constrain (ω), we replace it with the initial intensity spectral function A0(ω) (process number (7) in the figure).

number

[0040] Subsequently, by repeating the above processes (1) to (7) multiple times, the phase spectral function Ψ in the waveform function is obtained. n The phase spectral shape represented by (ω) can be made to approximate the phase spectral shape corresponding to the desired time-intensity waveform. The final phase spectral function Ψ IFTA (ω) is used to calculate the modulation pattern.

[0041] The above-described procedure for calculating the phase spectrum is used to calculate the phase spectrum corresponding to each of the multiple time-intensity waveforms set in the waveform setting unit 11. Furthermore, the above-described example of the iterative Fourier method can be used not only to calculate the phase spectrum but also to calculate the intensity spectrum corresponding to each of the multiple time-intensity waveforms set in the waveform setting unit 11 in the iterative Fourier transform unit 14a. Note that the calculation method for the phase spectrum and intensity spectrum is not limited to the above-described example of the iterative Fourier method, and may include an iterative Fourier method with a different calculation procedure.

[0042] The data determination unit 16 is provided with each of the multiple data representing each of the multiple modulation patterns calculated by the data generation unit 15. Based on each of the multiple data corresponding to each of the multiple time-intensity waveforms set in the waveform setting unit 11, the data determination unit 16 calculates the generation efficiency in the SLM24 corresponding to each of the multiple time-intensity waveforms, and determines the data to control the SLM24 based on the generation efficiency. For example, the data determination unit 16 determines the data representing the modulation pattern with the highest generation efficiency as the data to control the SLM24. The generation efficiency is the value obtained by dividing the energy of the output light Ld by the energy of the input light La.

[0043] Figure 9 is a flowchart illustrating the data creation method implemented by the data creation device 1 described above. The data creation program described above causes the computer processor 101 (see Figure 6) to execute each step included in this flowchart. As shown in Figure 9, first, the waveform setting unit 11 sets up a plurality of time intensity waveforms based on information about the desired time intensity waveform received as input (waveform setting step S1). Next, the phase spectrum design unit and the intensity spectrum design unit calculate phase spectra and intensity spectra, respectively, to bring the time intensity waveform closer to each of the plurality of time intensity waveforms set up in the waveform setting unit 11 (spectrum design step S2).

[0044] The spectral design step S2 includes a phase spectral design step S31 and an intensity spectral design step S41. The phase spectral design step S31 includes an iterative Fourier transform step S32 by the iterative Fourier transform unit 13a. The details of the iterative Fourier transform step S32 are the same as the operation of the iterative Fourier transform unit 13a described above. The final obtained phase spectral function Ψ IFTA (ω) is provided in the subsequent data generation step S5. The intensity spectrum design step S41 also includes an iterative Fourier transform step S42 by the iterative Fourier transform unit 14a. The details of the iterative Fourier transform step S42 are the same as the operation of the iterative Fourier transform unit 14a. The final obtained intensity spectrum function A IFTA (ω) is provided in the subsequent data generation step S5.

[0045] In data generation step S5, the phase spectral function Ψ IFTA (ω) and intensity spectral function A IFTA A modulation pattern is calculated based on (ω). In the data generation step S5, multiple modulation patterns corresponding to the multiple time-intensity waveforms set in the waveform setting unit 11 are calculated. These multiple modulation patterns are provided in the data determination step S6.

[0046] In the data determination step S6, the generation efficiency in the SLM24 for each of the multiple time-intensity waveforms corresponding to each of the multiple modulation patterns is calculated based on each of the multiple modulation patterns, and the modulation pattern presented to the SLM24 is determined based on the generation efficiency.

[0047] The effects obtained by the data creation device 1, data creation method, and data creation program according to this embodiment, as described above, will now be explained.

[0048] The data creation device 1, data creation method, and data creation program create multiple data sets based on each of the multiple time-intensity waveforms, each containing multiple optical pulses and having varying peak values ​​for the multiple optical pulses contained within each waveform. From the created data sets, data for controlling the SLM24 is determined based on the generation efficiency in the spatial light modulator of each time-intensity waveform corresponding to each data set. This makes it possible to shape the optical pulses to approach the time-intensity waveform corresponding to the desired generation efficiency. Therefore, the generation efficiency of optical pulses for laser processing can be improved.

[0049] The data determination unit 16 may determine the data that controls the SLM24 with the highest generation efficiency from among multiple data. This makes it possible to shape the optical pulse to approach the time-intensity waveform with the highest generation efficiency. Therefore, the generation efficiency of optical pulses for laser processing can be further improved.

[0050] The minimum peak value of multiple light pulses may be 80% or more of the maximum peak value of multiple light pulses. This improves the accuracy of calculating the intensity spectral function and phase spectral function to approach the time-intensity waveform set in the waveform setting unit 11. Furthermore, it is possible to obtain processing results that are almost the same as when each peak value is uniform.

[0051] The minimum peak value may be between 80% and 95% of the maximum peak value. Having the minimum peak value at 80% or more of the maximum peak value improves the accuracy of calculating the intensity spectral function and phase spectral function in the waveform setting unit 11 to approach the time-intensity waveform set. Furthermore, processing results nearly identical to those obtained when each peak value is uniform can be obtained. Having the minimum peak value at 95% or less of the maximum peak value allows the data setting unit to set a time-intensity waveform with greater variation in the peak values ​​of multiple light pulses. Therefore, the possibility of shaping the light pulses to approach a time-intensity waveform with higher generation efficiency increases, thus further improving the generation efficiency of light pulses for laser processing.

[0052] The waveform setting unit 11 may set information regarding a time-intensity waveform containing 50 or fewer light pulses. This allows the light pulses to be shaped to approach a time-intensity waveform suitable for laser processing. The waveform setting unit 11 may set information regarding a time-intensity waveform containing 50 or fewer light pulses, for example, when the number of pulses has a greater impact on the processing result than generation efficiency and uniformity of peak values.

[0053] The waveform setting unit 11 may set information regarding a time-intensity waveform containing 20 or fewer light pulses. This allows the light pulses to be shaped to approach a time-intensity waveform suitable for laser processing. The waveform setting unit 11 may also set information regarding a time-intensity waveform containing 20 or fewer light pulses, for example, when the generation efficiency and uniformity of the peak value have a greater impact on the processing result than the number of pulses.

[0054] The waveform setting unit 11 may set information regarding a time-intensity waveform that includes multiple optical pulses with pulse intervals of 10 fs or more and 100 ps or less. This makes it possible to shape the optical pulses to approximate a time-intensity waveform suitable for laser processing.

[0055] Figure 10 shows the generation efficiency in the SLM24 for each number of pulses corresponding to the time-intensity waveform set in the waveform setting unit 11. Data point P1 is the generation efficiency when the peak values ​​of the multiple pulses included in the time-intensity waveform are uniform. Data point P2 is the minimum peak value V of the multiple pulses included in the time-intensity waveform. valley The maximum peak value is V peak This represents the generation efficiency when the value is 80%. Data point P3 is the minimum peak value V of the multiple pulses contained in the time-intensity waveform. valley The maximum peak value is V peak This represents the generation efficiency when the value is 90%. Data point P4 is the minimum peak value V of the multiple pulses contained in the time-intensity waveform. valley The maximum peak value is V peak This represents the generation efficiency when the value is 95% of the specified value. The setting conditions for each data point were a center wavelength of 800 nm, a spectral width of 10 nm, and a pulse interval of 0.5 ps. For each data point, the generation efficiency in the SLM24 corresponding to each of several different time-intensity waveforms, each containing multiple optical pulses and set in the waveform setting unit 11, is calculated, and the highest generation efficiency is displayed. Therefore, it was confirmed that among the multiple time-intensity waveforms, there are time-intensity waveforms that improve generation efficiency compared to the case where a time-intensity waveform with uniform peak values ​​of multiple pulses is set.

[0056] Figure 11(a) shows the spectral waveform corresponding to data point P1 in Figure 10 when there are 9 pulses, and Figure 11(b) shows the time intensity waveform corresponding to the spectral waveform. Similarly, Figure 12(a) shows the spectral waveform corresponding to data point P2 in Figure 10 when there are 9 pulses, and Figure 12(b) shows the time intensity waveform corresponding to the spectral waveform. In Figures 11(a) and 12(a), the horizontal axis represents wavelength (nm), and the vertical axis represents the intensity value of the intensity spectrum (in arbitrary units). In Figures 11(b) and 12(b), the horizontal axis represents time (ps), and the vertical axis represents light intensity (in arbitrary units). The generation efficiency in SLM24 corresponding to the time intensity waveform shown in Figure 11(b) was 56%. The generation efficiency in SLM24 corresponding to the time intensity waveform shown in Figure 12(b) was 83%. Therefore, it was confirmed that among multiple time-intensity waveforms, each containing multiple light pulses, there are time-intensity waveforms that result in higher generation efficiency in SLM24 compared to time-intensity waveforms containing multiple light pulses with uniform peak values.

[0057] Figure 13(a) shows the spectral waveform of output light Ld as an alternative example, and Figure 13(b) shows the time intensity waveform corresponding to the spectral waveform. In Figure 13(a), the horizontal axis represents wavelength (nm), and the vertical axis represents the intensity value of the intensity spectrum (in arbitrary units). In Figure 13(b), the horizontal axis represents time (ps), and the vertical axis represents light intensity (in arbitrary units). The setting conditions were a center wavelength of 800 nm, a spectral width of 30 nm, and a pulse interval of 0.5 ps. The generation efficiency in SLM24 corresponding to the time intensity waveform shown in Figure 13(b) was 82%. The generation efficiency in SLM24 corresponding to the time intensity waveform containing multiple light pulses with uniform peak values ​​was 56%. Therefore, an improvement in generation efficiency was confirmed.

[0058] Figure 14(a) shows the spectral waveform of output light Ld as an alternative example, and Figure 14(b) shows the time intensity waveform corresponding to the spectral waveform. In Figure 14(a), the horizontal axis represents wavelength (nm), and the vertical axis represents the intensity value of the intensity spectrum (in arbitrary units). In Figure 14(b), the horizontal axis represents time (ps), and the vertical axis represents light intensity (in arbitrary units). The setting conditions were a center wavelength of 800 nm, a spectral width of 10 nm, and a pulse interval of 2 ps. The generation efficiency in SLM24 corresponding to the time intensity waveform shown in Figure 14(b) was 73%. The generation efficiency in SLM24 corresponding to the time intensity waveform containing multiple light pulses with uniform peak values ​​was 64%. Therefore, an improvement in generation efficiency was confirmed. [Explanation of Symbols]

[0059] 1...Data creation device, 2...Optical control device, 11...Waveform setting unit, 12...Spectrum design unit, 13...Phase spectrum design unit, 14...Intensity spectrum design unit, 15...Data generation unit, 16...Data determination unit, 20...Optical system, 21...Light source, 22...Diffraction grating, 23...Lens, 24...SLM, 25...Lens, 26...Diffraction grating, 27...Modulation plane, 27a...Modulation region, 101...Processor, 102...ROM, 103...RAM, 104...Input device, 105...Output device, 106...Communication module, 107...Auxiliary storage device, La...Input light, Ld...Output light, P1~P4...Data points, S1...Waveform setting step, S2...Spectrum design step, S5...Data generation step, S6...Data determination step, S31...Phase spectrum design step, S41...Intensity spectrum design step, SC...Control signal.

Claims

1. A device for creating data to control a spatial light modulator that shapes light pulses for laser processing, A waveform setting unit sets information about multiple time-intensity waveforms, each containing multiple light pulses, which are all different from each other. A spectral design unit that generates each of a plurality of sets of intensity spectral functions and phase spectral functions based on each of the plurality of time-intensity waveforms, A data generation unit that creates each of a plurality of data based on each of the plurality of sets of the intensity spectral function and the phase spectral function, A data creation device comprising: a data determination unit that calculates the generation efficiency of each of the multiple time-intensity waveforms in the spatial light modulator based on each of the multiple data; and a data determination unit that determines data to control the spatial light modulator from among the multiple data based on the generation efficiency.

2. The data creation apparatus according to claim 1, wherein the data determination unit determines from the plurality of data the data that controls the spatial light modulator with the highest generation efficiency.

3. The data creation apparatus according to claim 1, wherein the minimum peak value of the plurality of light pulses is 80% or more of the maximum peak value of the plurality of light pulses.

4. The data creation device according to claim 3, wherein the minimum peak value is a value of 80% or more and 95% or less of the maximum peak value.

5. The data creation device according to claim 1, wherein the waveform setting unit sets information relating to the time-intensity waveform, which includes 50 or fewer light pulses.

6. The data creation device according to claim 5, wherein the waveform setting unit sets information regarding the time-intensity waveform, which includes 20 or fewer light pulses.

7. The data creation device according to claim 1, wherein the waveform setting unit sets information regarding the time-intensity waveform, which includes the plurality of optical pulses having a pulse interval of 10 fs or more and 100 ps or less.

8. A method for creating data to control a spatial light modulator that shapes light pulses for laser processing, A waveform setting step involves setting information about multiple time-intensity waveforms, each containing multiple light pulses, that are different from each other. A spectral design step that generates each of several sets of intensity spectral functions and phase spectral functions based on each of the aforementioned multiple time-intensity waveforms, A data generation step of creating each of the multiple data sets based on each of the multiple sets of intensity spectral functions and phase spectral functions, A data creation method comprising: a data determination step of calculating the generation efficiency of each of the multiple time-intensity waveforms in the spatial light modulator based on each of the multiple data; and determining data to control the spatial light modulator from the multiple data based on the generation efficiency.

9. A program that creates data to control a spatial light modulator that shapes light pulses for laser processing, A waveform setting step involves setting information about multiple time-intensity waveforms, each containing multiple light pulses, that are different from each other. A spectral design step that generates each of several sets of intensity spectral functions and phase spectral functions based on each of the aforementioned multiple time-intensity waveforms, A data generation step of creating each of the multiple data sets based on each of the multiple sets of intensity spectral functions and phase spectral functions, A data creation program comprising: a data determination step of calculating the generation efficiency of each of the multiple time-intensity waveforms in the spatial light modulator based on each of the multiple data; and determining data to control the spatial light modulator from the multiple data based on the generation efficiency.

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