Optical waveform measuring device, optical irradiation device, laser processing device, observation device, optical waveform measuring method, optical irradiation method, laser processing method, and observation method

Abstract

The present invention provides an apparatus and method for easily and accurately measuring the time waveform of target light. [Solution] The optical waveform measuring device 1 comprises a light source 10, a waveform generation unit 20, a measurement unit 30, and a calculation unit 40. The waveform generation unit 20 generates and outputs the light to be measured for time waveform measurement (target light) and a reference single optical pulse based on the optical pulse output from the light source 10. When input to the measurement unit 30, the target light and the reference single optical pulse are input with a time interval longer than the time width of each light being longer than the time interval of each light. The measurement unit 30 has the configuration of an autocorrelation analyzer and measures the shape of the autocorrelation of the time waveform of the light including the target light and the reference single optical pulse. The calculation unit 40 determines the time waveform of the target light based on the portion of this autocorrelation shape that represents the cross-correlation between the time waveform of the target light and the time waveform of the reference single optical pulse.

Description

Technical Field

[0001] The present invention relates to an optical waveform measuring apparatus, an optical irradiation apparatus, a laser processing apparatus, an observation apparatus, an optical waveform measuring method, an optical irradiation method, a laser processing method, and an observation method.

Background Art

[0002] Light used for applications such as processing, measurement, observation, etc. by light irradiation is required to have a time waveform suitable for the application. For example, in some cases, it is required to be an optical pulse train having a plurality of peaks temporally separated from each other. Light having a desired time waveform according to the application can be generated based on optical pulses output from a pulsed laser light source.

[0003] For example, the accuracy and efficiency of processing a processing object by light irradiation depend on the time waveform of the light irradiated onto the processing object. In order to perform high-precision and high-efficiency processing of the processing object, it is important to irradiate the processing object with light having a desired time waveform. Therefore, it is important to measure the time waveform of the light generated based on the input optical pulse and to control the light irradiated onto the processing object so as to have a desired time waveform based on the measurement result. The time waveform of light can be measured using a cross-correlator or an autocorrelator.

[0004] The cross-correlator inputs light (target light) to be measured for the time waveform and also inputs a reference single optical pulse, and measures the shape of the cross-correlation between the time waveform of the target light and the time waveform of the reference single optical pulse. The time waveform of the target light can be obtained based on this cross-correlation shape.

[0005] The autocorrelator measures the shape of the autocorrelation of the time waveform of the target light. The time waveform of the target light can be obtained based on this autocorrelation shape (see Non-Patent Document 1).

Prior Art Documents

Non-Patent Documents

[0006] [Non-Patent Document 1] Hikari Kogyo Co., Ltd., “Autocorrelation Method - Autocorrelator”, [online], [Retrieved November 15, 2024], Internet<URL:https: / / www.symphotony.com / products / ultrashort / ultrashortmenu / autocorrelator / > [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] When measuring the time waveform of a target light using a cross-correlator, the time waveform of the target light can be estimated with relatively high accuracy. However, since the target light and the reference single optical pulse are input to the cross-correlator separately, the optical system leading up to the input of each of the target light and the reference single optical pulse must be adjusted each time a measurement is taken, and this adjustment is not easy.

[0008] On the other hand, when measuring the time waveform of target light using an autocorrelation analyzer, only the target light needs to be input to the autocorrelation analyzer, making the adjustment of the optical system until the target light is input to the autocorrelation analyzer relatively easy. Autocorrelation analyzers are easier to use than cross-correlation analyzers. However, when the time waveform of the target light is complex, it is difficult to accurately determine the time waveform of the target light based on the autocorrelation shape. For example, when the target light is a light pulse train with two peaks spaced apart in time, it is difficult to estimate the difference in pulse shape or magnitude between these two peaks from the autocorrelation shape.

[0009] This disclosure was made to resolve the above-mentioned problems and aims to provide an apparatus and method that can easily and accurately measure the time waveform of target light. [Means for solving the problem]

[0010] The optical waveform measuring device disclosed herein is a device for measuring the time waveform of target light. A first aspect of the optical waveform measuring device of the present disclosure includes: (1) a waveform generation unit that generates and outputs a target light and a reference single optical pulse based on an optical pulse output from a light source; (2) a measurement unit that inputs the target light and the reference single optical pulse at a time interval longer than the time width of the target light and the time width of the reference single optical pulse, and measures the shape of the autocorrelation of the optical time waveform including the target light and the reference single optical pulse; and (3) a calculation unit that determines the time waveform of the target light based on the portion of the autocorrelation shape measured by the measurement unit that represents the cross-correlation between the time waveform of the target light and the time waveform of the reference single optical pulse.

[0011] In a second aspect of the optical waveform measuring device of the present disclosure, in addition to the first aspect, the waveform generation unit includes a dispersion element that outputs each wavelength component of an optical pulse output from a light source in a direction corresponding to the wavelength, and a spatial light modulator that receives the light of each wavelength component output from the dispersion element, spatially modulates it, and generates a target light and a reference single optical pulse.

[0012] In a third aspect of the optical waveform measuring device of the present disclosure, in addition to the first aspect, the waveform generation unit includes a dispersion element that outputs each wavelength component of an optical pulse output from a light source in a direction corresponding to the wavelength, and a spatial light modulator that receives the light of each wavelength component output from the dispersion element, inputs the linearly polarized component of the first direction, spatially modulates it to generate target light, and uses the linearly polarized component of the second direction as a reference single optical pulse without modulation.

[0013] In a fourth aspect of the optical waveform measuring device of this disclosure, in addition to the first aspect, the waveform generation unit includes a diffraction grating that outputs each wavelength component of an optical pulse output from a light source in a direction corresponding to the wavelength, and a spatial light modulator that receives the light of each wavelength component diffracted and output by the diffraction grating, spatially modulates it, and generates target light, wherein the zeroth-order light generated by the diffraction grating is used as a reference single optical pulse.

[0014] In a fifth aspect of the optical waveform measuring device of this disclosure, in addition to the first aspect, the waveform generation unit includes a branching unit that splits an optical pulse output from a light source into two and outputs a first branched optical pulse and a second branched optical pulse, a dispersion element that outputs each wavelength component of the first branched optical pulse in a direction corresponding to the wavelength, and a spatial optical modulator that receives the light of each wavelength component output from the dispersion element and spatially modulates it to generate target light, wherein the second branched optical pulse is a reference single optical pulse.

[0015] In a sixth aspect of the optical waveform measuring device of the present disclosure, in addition to the first to fifth aspects, the waveform generation unit further comprises an optical stopper for blocking a reference single-pulse light.

[0016] In a first aspect of the light irradiation device of the present disclosure, the device comprises a light waveform measuring device according to the first to sixth aspects, a control unit that controls a waveform generation unit so that the time waveform of the target light determined by a calculation unit becomes a desired time waveform, and a light irradiation unit that irradiates an object with the target light output from the waveform generation unit.

[0017] In a first aspect of the laser processing apparatus of this disclosure, the apparatus is equipped with a light irradiation device of the first aspect, and the light source is a laser light source.

[0018] In a first aspect of the observation device of this disclosure, the device comprises a light irradiation device of the first aspect and a light detection unit for detecting light from an object due to light irradiation.

[0019] The optical waveform measurement method disclosed herein is a method for measuring the time waveform of a target light. A first aspect of the optical waveform measurement method of the present disclosure comprises: (1) a waveform generation step in which a waveform generation unit generates and outputs a target light and a reference single optical pulse based on an optical pulse output from a light source; (2) a measurement step in which a measurement unit inputs the target light and the reference single optical pulse at a time interval longer than the time width of the target light and the time width of the reference single optical pulse, and measures the shape of the autocorrelation of the optical time waveform including the target light and the reference single optical pulse; and (3) a calculation step in which the time waveform of the target light is determined based on the portion of the shape of the autocorrelation measured in the measurement step that represents the cross-correlation between the time waveform of the target light and the time waveform of the reference single optical pulse.

[0020] In a second aspect of the optical waveform measurement method of the present disclosure, in addition to the first aspect, in the waveform generation step, each wavelength component of the optical pulse output from the light source is output in a direction corresponding to the wavelength by a dispersive element, and the light is spatially modulated by a spatial light modulator that receives the light of each wavelength component output from the dispersive element to generate a target light and a reference single optical pulse.

[0021] In a third aspect of the optical waveform measurement method of the present disclosure, in addition to the first aspect, in the waveform generation step, each wavelength component of the optical pulse output from the light source is output in a direction corresponding to the wavelength by a dispersive element, and the linearly polarized component of the first direction of the light is input to a spatial light modulator that receives the light of each wavelength component output from the dispersive element, and is spatially modulated to generate target light, while the linearly polarized component of the second direction is left unmodulated as a reference single optical pulse.

[0022] In a fourth aspect of the optical waveform measurement method of this disclosure, in addition to the first aspect, in the waveform generation step, each wavelength component of the optical pulse output from the light source is output in a direction corresponding to the wavelength by a diffraction grating, and the light of each wavelength component diffracted and output by the diffraction grating is input to a spatial light modulator, which then spatially modulates the light to generate target light, and the zeroth-order light generated by the diffraction grating is used as a reference single optical pulse.

[0023] In a fifth aspect of the optical waveform measurement method of the present disclosure, in addition to the first aspect, in the waveform generation step, an optical pulse output from a light source is branched into two by a branching unit to output a first branched optical pulse and a second branched optical pulse, each wavelength component of the first branched optical pulse is output in a direction corresponding to the wavelength by a dispersion element, and the light of each wavelength component output from the dispersion element is spatially modulated by a spatial light modulator that inputs the light to generate target light, and the second branched optical pulse is used as a reference single optical pulse.

[0024] The light irradiation method of the present disclosure is a method of irradiating an object with target light. The first aspect of the light irradiation method of the present disclosure includes: (1) a waveform generation step of generating and outputting target light and a reference single optical pulse based on an optical pulse output from a light source; (2) a measurement step of measuring the shape of the autocorrelation of the temporal waveform of light including the target light and the reference single optical pulse; (3) a calculation step of obtaining the temporal waveform of the target light based on a portion representing the cross-correlation between the temporal waveform of the target light and the temporal waveform of the reference single optical pulse among the shapes of the autocorrelation measured in the measurement step; (4) an optical control step of controlling the temporal waveform of the target light generated by the waveform generation step so that the temporal waveform of the target light obtained in the calculation step becomes a desired temporal waveform; and (5) an irradiation step of irradiating the object with the target light generated in the waveform generation step and controlled in the optical control step. The target light and the reference single optical pulse are separated from each other at a time interval longer than either the temporal width of the target light or the temporal width of the reference single optical pulse.

[0025] The laser processing method of the present disclosure is a method of processing an object with target light A first aspect of the laser processing method of the present disclosure includes: (1) a waveform generation step of generating and outputting target light and a reference single light pulse based on a laser light pulse output from a light source; (2) a measurement step of measuring the shape of the autocorrelation of the temporal waveform of the light including the target light and the reference single light pulse; (3) a calculation step of obtaining the temporal waveform of the target light based on a portion representing the cross-correlation between the temporal waveform of the target light and the temporal waveform of the reference single light pulse among the shapes of the autocorrelations measured in the measurement step; (4) an optical control step of controlling the temporal waveform of the target light generated by the waveform generation step so that the temporal waveform of the target light obtained in the calculation step becomes a desired temporal waveform; and (5) a processing step of condensing the target light generated in the waveform generation step and controlled in the optical control step onto or inside an object to process the object. The target light and the reference single light pulse are separated from each other at a time interval longer than either the temporal width of the target light or the temporal width of the reference single light pulse.

[0026] The observation method of the present disclosure is a method for observing an object. A first aspect of the observation method of the present disclosure includes: (1) a waveform generation step of generating and outputting target light and a reference single light pulse based on a light pulse output from a light source; (2) a measurement step of measuring the shape of the autocorrelation of the temporal waveform of the light including the target light and the reference single light pulse; (3) a calculation step of obtaining the temporal waveform of the target light based on a portion representing the cross-correlation between the temporal waveform of the target light and the temporal waveform of the reference single light pulse among the shapes of the autocorrelations measured in the measurement step; (4) an optical control step of controlling the temporal waveform of the target light generated by the waveform generation step so that the temporal waveform of the target light obtained in the calculation step becomes a desired temporal waveform; (5) an optical irradiation step of condensing the target light generated in the waveform generation step and controlled in the optical control step onto or inside an object; and (6) an optical detection step of detecting the light generated in the object by the light condensed in the optical irradiation step. The target light and the reference single light pulse are separated from each other at a time interval longer than either the temporal width of the target light or the temporal width of the reference single light pulse. [Effects of the Invention]

[0027] According to this disclosure, the time waveform of the target light can be measured simply and accurately. [Brief explanation of the drawing]

[0028] [Figure 1] Figure 1 shows the configuration of the optical waveform measuring device 1. [Figure 2] Figure 2 illustrates the target optical pulse Po and the reference single optical pulse Pr input to the measurement unit 30. [Figure 3] Figure 3 shows the configuration of the measuring unit 30. [Figure 4] Figure 4 is a diagram illustrating the autocorrelation acquired by the measurement unit 30. [Figure 5] Figure 5 shows the configuration of the waveform generation unit 20A. [Figure 6] Figure 6 shows the configuration of the waveform generation unit 20B. [Figure 7] Figure 7 shows the configuration of the waveform generation unit 20C. [Figure 8] Figure 8 shows the configuration of the waveform generation unit 20D. [Figure 9] Figure 9 shows a portion of the autocorrelation shape obtained by the measurement unit 30 in an experiment conducted using the configuration of the waveform generation unit 20D (Figure 8). [Figure 10] Figure 10 shows a portion of the autocorrelation shape obtained by the measurement unit 30 in an experiment conducted using the configuration of the waveform generation unit 20D (Figure 8). [Figure 11] Figure 11 shows a portion of the autocorrelation shape obtained by the measurement unit 30 in an experiment conducted using the configuration of the waveform generation unit 20D (Figure 8). [Figure 12] Figure 12 is a flowchart showing an example of an optical waveform measurement method using the optical waveform measuring device 1. [Figure 13] Figure 13 shows the configuration of the light irradiation device 2. [Figure 14]Figure 14 is a flowchart showing an example of a light irradiation method using the light irradiation device 2. [Figure 15] Figure 15 is a flowchart showing an example of a laser processing method using a laser processing device. [Figure 16] Figure 16 is a flowchart showing an example of an observation method using a microscope. [Modes for carrying out the invention]

[0029] Hereinafter, embodiments for carrying out this disclosure will be described in detail with reference to the attached drawings. In the description of the drawings, the same elements will be denoted by the same reference numerals, and redundant descriptions will be omitted. This disclosure is not limited to these examples, but is indicated by the claims, and all modifications within the meaning and scope equivalent to the claims are intended.

[0030] Figure 1 shows the configuration of the optical waveform measuring device 1. The optical waveform measuring device 1 comprises a light source 10, a waveform generation unit 20, a measurement unit 30, and a calculation unit 40. The light source 10 repeatedly outputs optical pulses at a constant repetition frequency. The light source 10 is preferably a pulsed laser light source.

[0031] The waveform generation unit 20 is optically connected to the light source 10 and receives the light pulses output from the light source 10 as input. Based on the input light pulses, the waveform generation unit 20 generates and outputs the light (target light) Po that is the subject of time waveform measurement, and also generates and outputs a reference single light pulse Pr. The target light Po is generated to have a time waveform appropriate to the application. The reference single light pulse Pr may have the same time waveform as the light pulse output from the light source 10. Preferably, the reference single light pulse Pr has a time waveform with a narrower time width than the light pulse output from the light source 10.

[0032] The waveform generation unit 20 may include a dispersion element that outputs each wavelength component of the optical pulse output from the light source 10 in a direction corresponding to the wavelength, and a spatial light modulator that inputs the light of each wavelength component output from the dispersion element and spatially modulates it. The dispersion element is, for example, a diffraction grating or a prism. The waveform generation unit 20 may generate both the target light Po and the reference single light pulse Pr by modulating the optical pulse based on the modulation pattern presented to the spatial light modulation element. Alternatively, the waveform generation unit 20 may use a spatial light modulator that selectively modulates linearly polarized light of a first direction, modulate the linearly polarized component of the optical pulse of the first direction based on the modulation pattern presented to the spatial light modulation element to generate the target light Po, and leave the linearly polarized component of the optical pulse of the second direction unmodulated as the reference single light pulse Pr. Specific examples of the configuration of the waveform generation unit 20 will be described later.

[0033] The measurement unit 30 is optically connected to the waveform generation unit 20 and inputs the target optical light Po and the reference single optical pulse Pr output from the waveform generation unit 20 to a common input terminal. When inputting to this input terminal, the target optical light Po and the reference single optical pulse Pr are input with a time interval ΔT that is longer than either the time width To of the target optical light Po or the time width Tr of the reference single optical pulse Pr (Figure 2). This time interval ΔT is set based on the difference in the optical path lengths of the target optical light Po and the reference single optical pulse Pr. The temporal order of the target optical light Po and the reference single optical pulse Pr at the time of input is arbitrary. The measurement unit 30 has an autocorrelation configuration and measures the shape of the autocorrelation of the time waveform of the light including the target optical light Po and the reference single optical pulse Pr.

[0034] The calculation unit 40 is electrically connected to the measurement unit 30 and receives autocorrelation data measured by the measurement unit 30. The calculation unit 40 determines the time waveform of the target optical element Po based on the portion of this autocorrelation shape that represents the cross-correlation between the time waveform of the target optical element Po and the time waveform of the reference single optical pulse Pr.

[0035] The waveform generation of the target light Po by the waveform generation unit 20 can be controlled so that the time waveform of the target light Po obtained becomes the desired time waveform. Furthermore, by using the target light Po with the desired time waveform, processing and measurement can be performed with higher precision and efficiency.

[0036] The optical waveform measurement method comprises a waveform generation step, a measurement step, and a calculation step. In the waveform generation step, the waveform generation unit 20 generates and outputs a target optical pulse Po and a reference single optical pulse Pr based on the optical pulse output from the light source 10. In the measurement step, the measurement unit 30 inputs the target optical pulse Po and the reference single optical pulse Pr at a time interval longer than the time width of either the target optical pulse Po or the reference single optical pulse Pr, and measures the shape of the autocorrelation of the optical time waveform including the target optical pulse Po and the reference single optical pulse Pr. In the calculation step, the time waveform of the target optical pulse Po is determined based on the portion of the autocorrelation shape measured in the measurement step that represents the cross-correlation between the time waveform of the target optical pulse Po and the time waveform of the reference single optical pulse Pr.

[0037] Figure 3 shows the configuration of the measurement unit 30. The measurement unit 30 includes a beam splitter 31, mirrors 32a to 32f, a stage 33, a nonlinear optical element 34, and a photodetector 35.

[0038] The beam splitter 31 receives light including the target light Po and the reference single light pulse Pr output from the waveform generation unit 20, splits it into two, outputs one to mirror 32a and the other to mirror 32f. The splitting ratio of the beam splitter 31 may be 1:1. The light output from the beam splitter 31 to mirror 32a is sequentially reflected by mirrors 32a to 32e and input to the nonlinear optical element 34. The light output from the beam splitter 31 to mirror 32f is reflected by mirror 32f and input to the nonlinear optical element 34.

[0039] Mirrors 32c and 32d are mounted on stage 33. Stage 33 is movable in the direction of the double arrows in the figure. Moving stage 33 sets the difference in optical path length between the optical path from beam splitter 31 through mirrors 32a to 32e to nonlinear optical element 34 and the optical path from beam splitter 31 through mirror 32f to nonlinear optical element 34. In other words, by moving stage 33, the time difference τ of the timing at which each of the two beams output from beam splitter 31 reaches the nonlinear optical element 34 can be set to any value.

[0040] Two beams of light are incident on the nonlinear optical element 34 from different directions. This generates a second harmonic in the nonlinear optical element 34. Examples of nonlinear optical elements 34 include KTP (KTiOPO4) crystal, LBO (LiB3O5) crystal, and BBO (β-BaB2O4) crystal. The photodetector 35 detects the intensity of the second harmonic output from the nonlinear optical element 34 for each light pulse output from the light source 10. The intensity of this second harmonic corresponds to the magnitude of the correlation between the time waveforms of the two beams of light incident on the nonlinear optical element 34, and corresponds to the magnitude of the autocorrelation of the time waveforms of the light including the target light Po and the reference single light pulse Pr.

[0041] When the time difference τ between two beams of light incident on the nonlinear optical element 34 is set to a specific value by the movement of the stage 33, the intensity of the second harmonic output from the nonlinear optical element 34 is detected by the photodetector 35. The relationship between the time difference τ and the second harmonic intensity represents the shape of the autocorrelation of the time waveform of the light, including the target light Po and the reference single light pulse Pr.

[0042] Figure 4 is a diagram illustrating the autocorrelation acquired by the measurement unit 30. The autocorrelation G(τ) of a given time waveform I(t) is expressed by the following equation (1). Assume that the time waveform I(t) is represented by the sum of the time waveform Io(t) of the target optical pulse Po and the time waveform Ir(t) of the reference single optical pulse Pr (see equation (2) below). In this case, the autocorrelation G(τ) is expressed by the following equation (3). t is a variable representing time. τ is the time difference set by the stage 33.

[0043]

number

[0044]

number

[0045]

number

[0046] The first term on the right-hand side of equation (3) represents the autocorrelation of the time waveform Io(t) of the target optical energy Po. The second term represents the autocorrelation of the time waveform Ir(t) of the reference single optical pulse Pr. The third and fourth terms represent the crosscorrelation between the time waveform Io(t) of the target optical energy Po and the time waveform Ir(t) of the reference single optical pulse Pr.

[0047] The autocorrelation of the time waveform Io(t) of the target optical pulse Po (term 1) and the autocorrelation of the time waveform Ir(t) of the reference single optical pulse Pr (term 2) are distributed overlapping each other within the range that includes a time difference τ=0 (range b in Figure 4).

[0048] In contrast, the cross-correlation between the third and fourth terms (the cross-correlation between the time waveform Io(t) of the target optical fiber Po and the time waveform Ir(t) of the reference single optical pulse Pr) is distributed in a range away from the time difference τ=0 (ranges a and c in Figure 4). Either one of the third or fourth terms is distributed in range a in Figure 4, and the other is distributed in range c in Figure 4. When input to the measurement unit 30, the target optical fiber Po and the reference single optical pulse Pr are input with a time interval ΔT that is longer than either the time width To of the target optical fiber Po or the time width Tr of the reference single optical pulse Pr (Figure 2), so both ranges a and c are spaced apart from range b.

[0049] Therefore, from the shape of the autocorrelation acquired by the measurement unit 30, a portion representing the cross-correlation between the time waveform Io(t) of the target optical pulse Po and the time waveform Ir(t) of the reference single optical pulse Pr (range a or range c in Figure 4) can be extracted. Based on the shape of this portion representing the cross-correlation, the time waveform Io(t) of the target optical pulse Po can then be determined.

[0050] Since the measurement unit 30 of the optical waveform measuring device 1 has an autocorrelation configuration, the optical system can be easily adjusted and it is easy to use. Furthermore, from the shape of the autocorrelation acquired by the measurement unit 30, a portion representing the cross-correlation between the time waveform Io(t) of the target optical light Po and the time waveform Ir(t) of the reference single optical pulse Pr is extracted, and the time waveform Io(t) of the target optical light Po is determined based on the shape of this extracted portion representing the cross-correlation, so the time waveform Io(t) of the target optical light Po can be accurately estimated. From this, it becomes easy to generate a target optical light Po with a desired time waveform Io(t) using the waveform generation unit 20, and by using this target optical light Po, high-precision and high-efficiency processing and measurement can be performed.

[0051] Next, we will explain a specific example of the configuration of the waveform generation unit 20 using Figures 5 to 8. Figure 5 shows the configuration of the waveform generation unit 20A. The waveform generation unit 20A includes a diffraction grating 51, lenses 52, 53, a spatial light modulator 54, a mirror 55, and a mirror 61.

[0052] The diffraction grating 51, acting as a dispersion element, receives the light pulse output from the light source 10 and diffracts the light pulse at a diffraction angle corresponding to its wavelength, thereby spatially separating the light pulse by wavelength and outputting light of each wavelength in different directions. Lenses 52 and 53 receive the light of each wavelength that has been diffracted by the diffraction grating 51 and output in different directions, collimate it, and output the collimated light to the spatial light modulator 54.

[0053] The spatial light modulator 54 has a modulation plane that can modulate the phase of light at each pixel position. The spatial light modulator 54 inputs the light collimated by lenses 52 and 53 to the modulation plane, modulates its phase according to its position (i.e., according to the wavelength of light) at the modulation plane, and outputs the modulated light. The spatial light modulator 54 may also be capable of amplitude modulation in addition to phase modulation of light at each pixel position. The modulation pattern at the modulation plane is presented by an external electrical signal.

[0054] The spatial light modulator 54 can adjust the time waveform of light by performing phase modulation according to the wavelength. Furthermore, the spatial light modulator 54 can adjust the spectral shape of light by performing amplitude modulation according to the wavelength.

[0055] Lenses 53 and 52 focus the light of each wavelength, which has been spatially modulated and output by the spatial light modulator 54, onto the diffraction grating 51. The diffraction grating 51 diffracts the light of each wavelength that has arrived from lenses 53 and 52 and outputs it as target light Po on the same optical path.

[0056] A portion of the light pulse output from the light source 10 passes through the diffraction grating 51 as zero-order light. The zero-order light that has passed through the diffraction grating 51 is reflected by the mirror 55 and passes through the diffraction grating 51 again. The diffraction grating 51 outputs this transmitted zero-order light as a reference single light pulse Pr.

[0057] The mirror 61 reflects the target light Po and the reference single light pulse Pr output from the diffraction grating 51 and outputs them to the measurement unit 30.

[0058] The waveform generation unit 20A may also include an optical stopper 59 that can be positioned in the optical path between the diffraction grating 51 and the mirror 55. The optical stopper 59 is positioned outside the optical path between the diffraction grating 51 and the mirror 55 during optical waveform measurement, while it is positioned in the optical path between the diffraction grating 51 and the mirror 55 during light irradiation or optical processing. This prevents the reference single optical pulse Pr from irradiating the object S during light irradiation or optical processing.

[0059] Figure 6 shows the configuration of the waveform generation unit 20B. The waveform generation unit 20B includes a diffraction grating 51, lenses 52, 53, a spatial light modulator 54, a half mirror 56, and a mirror 57.

[0060] The half-mirror 56 is a branching unit that receives the light pulse output from the light source 10 and splits it into a first branched light pulse and a second branched light pulse. The first branched light pulse is output to the diffraction grating 51, and the second branched light pulse is output to the mirror 57. The first branched light pulse output from the half-mirror 56 to the diffraction grating 51 is converted into a target light Po by the diffraction grating 51, lenses 52, 53, and spatial light modulator 54 in the same manner as the waveform generation unit 20A (Figure 5), and returns to the half-mirror 56. The second branched light pulse output from the half-mirror 56 to the mirror 57 is reflected by the mirror 57 and then returns to the half-mirror 56 as a reference single light pulse Pr.

[0061] The half-mirror 56 receives the target light Po arriving from the diffraction grating 51 and the reference single light pulse Pr arriving from the mirror 57, combines both lights, and outputs the combined light to the measurement unit 30.

[0062] The waveform generation unit 20B may also include an optical stopper 59 that can be positioned in the optical path between the half mirror 56 and the mirror 57. The optical stopper 59 is positioned outside the optical path between the half mirror 56 and the mirror 57 during optical waveform measurement, but is positioned in the optical path between the half mirror 56 and the mirror 57 during light irradiation or optical processing. This prevents the reference single optical pulse Pr from irradiating the object S during light irradiation or optical processing.

[0063] Figure 7 shows the configuration of the waveform generation unit 20C. The waveform generation unit 20C includes a diffraction grating 51, lenses 52, 53, a spatial light modulator 54, a mirror 57, a polarizing beam splitter 58, a mirror 61, half-wave plates 62, 63, and a polarizer 64.

[0064] The half-wave plate 62 receives the light pulse output from the light source 10, converts it into a light pulse having both p-polarization and s-polarization components, and outputs it. The polarization beam splitter 58 is a splitter that receives the light pulse output from the half-wave plate 62 and splits it into a p-polarization component and an s-polarization component. It outputs the p-polarized light pulse (first split light pulse) to the diffraction grating 51 and the s-polarized light pulse (second split light pulse) to the mirror 57.

[0065] The p-polarized light pulse output from the polarizing beam splitter 58 to the diffraction grating 51 is converted into a target light Po by the diffraction grating 51, lenses 52, 53, and spatial light modulator 54 in the same manner as in the waveform generation unit 20A (Figure 5), and returns to the polarizing beam splitter 58. The s-polarized light pulse output from the polarizing beam splitter 58 to the mirror 57 is reflected by the mirror 57 and then returns to the polarizing beam splitter 58 as a reference single light pulse Pr.

[0066] The polarization beam splitter 58 receives p-polarized target light Po from the diffraction grating 51 and an s-polarized reference single light pulse Pr from the mirror 57, combines both lights, and outputs the combined light to the mirror 61.

[0067] The mirror 61 reflects the p-polarized target light Po and the s-polarized reference single light pulse Pr output from the polarizing beam splitter 58 onto the half-wave plate 63. The half-wave plate 63 rotates the polarization direction of both the target light Po and the reference single light pulse Pr by 45 degrees and outputs them to the polarizer 64. The polarizer 64 selectively transmits the linearly polarized component of one direction from the target light Po and the reference single light pulse Pr output from the half-wave plate 63 and outputs it to the measurement unit 30.

[0068] The waveform generation unit 20C may also include an optical stopper 59 that can be positioned in the optical path between the polarizing beam splitter 58 and the mirror 57. The optical stopper 59 is positioned outside the optical path between the polarizing beam splitter 58 and the mirror 57 during optical waveform measurement, but is positioned in the optical path between the polarizing beam splitter 58 and the mirror 57 during light irradiation or optical processing. This prevents the reference single optical pulse Pr from irradiating the object S during light irradiation or optical processing.

[0069] If the autocorrelation analyzer of the measurement unit 30 is polarization-dependent, it is preferable to input a linearly polarized component in one direction from the target light Po and the reference single light pulse Pr to the measurement unit 30. Furthermore, in this configuration, the intensity ratio between the target light Po and the reference single light pulse Pr can be adjusted using the half-wave plates 62 and 63, so that the light intensity conditions can be optimized when measuring the autocorrelation shape.

[0070] Figure 8 shows the configuration of the waveform generation unit 20D. The waveform generation unit 20D includes a half-wave plate 71, a polarizing beam splitter 72, a half-wave plate 73, a diffraction grating 74, a lens 75, a spatial light modulator 76, a mirror 77, a half-wave plate 78, a mirror 79, a polarizing beam splitter 81, a half-wave plate 82, and a polarizing beam splitter 83.

[0071] The half-wave plate 71 receives the light pulse output from the light source 10, converts it into a light pulse having both p-polarized and s-polarized components, and outputs it. The polarization beam splitter 72 is a splitter that receives the light pulse output from the half-wave plate 71 and splits it into a p-polarized component and an s-polarized component, outputting the p-polarized light pulse to the half-wave plate 73 and the s-polarized light pulse to the half-wave plate 78.

[0072] The half-wave plate 73 converts the p-polarized light pulses arriving from the polarizing beam splitter 72 into s-polarized light pulses, and outputs these converted s-polarized light pulses to the diffraction grating 74. The s-polarized light pulses output from the half-wave plate 73 to the diffraction grating 74 are converted into target light Po by the diffraction grating 74, lens 75, and spatial light modulator 76, in the same manner as the diffraction grating 51, lenses 52, 53, and spatial light modulator 54 of the waveform generation unit 20A (Figure 5). The mirror 77 reflects this target light Po to the polarizing beam splitter 81.

[0073] The half-wave plate 78 converts the s-polarized light pulses arriving from the polarizing beam splitter 72 into p-polarized light, and outputs these converted p-polarized light pulses to the mirror 79. The mirror 79 reflects the p-polarized light pulses output from the half-wave plate 78 as a reference single light pulse Pr to the polarizing beam splitter 81.

[0074] The polarization beam splitter 81 receives the s-polarized target light Po arriving from mirror 77 and the p-polarized reference single light pulse Pr arriving from mirror 79, combines the two lights, and outputs them to the half-wave plate 82. The half-wave plate 82 receives the target light Po and the reference single light pulse Pr output from the polarization beam splitter 81, rotates the polarization direction of both lights by 45 degrees, and outputs them to the polarization beam splitter 83. The polarization beam splitter 83 selectively transmits the p-polarized component of the target light Po and reference single light pulse Pr output from the half-wave plate 82 and outputs it to the measurement unit 30.

[0075] The waveform generation unit 20D may also include an optical stopper 59 that can be positioned in the optical path between the polarizing beam splitter 72 and the polarizing beam splitter 81. The optical stopper 59 is positioned outside the optical path between the polarizing beam splitter 72 and the polarizing beam splitter 81 during optical waveform measurement, but is positioned in the optical path between the polarizing beam splitter 72 and the polarizing beam splitter 81 during light irradiation or optical processing. This prevents the reference single optical pulse Pr from irradiating the object S during light irradiation or optical processing.

[0076] In this configuration as well, if the autocorrelation analyzer of the measurement unit 30 is polarization-dependent, a linearly polarized component in one direction of the target light Po and the reference single light pulse Pr can be input to the measurement unit 30. Furthermore, the half-wave plates 71 and 82 allow adjustment of the intensity ratio between the target light Po and the reference single light pulse Pr, thereby optimizing the light intensity conditions when measuring the autocorrelation shape.

[0077] Figures 9 to 11 show the autocorrelation shapes obtained by the measurement unit 30 in experiments conducted using the configuration of the waveform generation unit 20D (Figure 8). In all cases, the time interval ΔT between the target optical pulse Po and the reference single optical pulse Pr was set to approximately 100 ps.

[0078] The autocorrelation shape shown in Figure 9 was obtained for the target optical signal Po (2 peaks, peak interval 0.5 ps) generated solely by phase modulation by the spatial optical modulator 76 of the waveform generation unit 20D. The autocorrelation shape shown in Figure 10 was obtained for the target optical signal Po (2 peaks, peak interval 2 ps) generated solely by phase modulation by the spatial optical modulator 76 of the waveform generation unit 20D. The autocorrelation shape shown in Figure 11 was obtained for the target optical signal Po (5 peaks, peak interval 0.5 ps) generated by both phase modulation and intensity modulation by the spatial optical modulator 76 of the waveform generation unit 20D.

[0079] In all of these autocorrelation shapes, it can be observed that the cross-correlation between the time waveform of the target optical fiber Po and the time waveform of the reference single optical pulse Pr is distributed within the range that includes a time difference τ = 100 ps. Based on this cross-correlation shape, the time waveform of the target optical fiber Po can be accurately determined.

[0080] Figure 12 is a flowchart illustrating an example of an optical waveform measurement method using the optical waveform measuring device 1. In the waveform generation step S11, a target optical pulse Po and a reference single optical pulse Pr are generated and output based on the optical pulses output from the light source 10. In the measurement step S12, the shape of the autocorrelation of the optical time waveform including the target optical pulse Po and the reference single optical pulse Pr is measured. In the calculation step S13, the time waveform of the target optical pulse Po is determined based on the portion of the autocorrelation shape measured in the measurement step S12 that represents the cross-correlation between the time waveform of the target optical pulse Po and the time waveform of the reference single optical pulse Pr. Note that the target optical pulse Po and the reference single optical pulse Pr generated in the waveform generation step S11 are separated from each other by a time interval longer than the time width of either the target optical pulse Po or the time width of the reference single optical pulse Pr.

[0081] Figure 13 shows the configuration of the light irradiation device 2. In addition to the configuration of the light waveform measuring device 1 shown in Figure 1, the light irradiation device 2 includes a control unit 91, a mirror 92, and a light irradiation unit 93. The light irradiation device 2 controls the generation of the target light Po by the waveform generation unit 20 so that the time waveform of the target light Po determined by the calculation unit 40 becomes a desired time waveform, and irradiates the target light Po onto the target object S via the light irradiation unit 93.

[0082] The control unit 91 controls the generation of target light Po by the waveform generation unit 20 so that the time waveform of the target light Po determined by the calculation unit 40 becomes a desired time waveform. For example, if the waveform generation unit 20 is equipped with a spatial light modulator 76, the control unit 91 presents a modulation pattern that results in a desired time waveform to the spatial light modulator 76. As a result, the waveform generation unit 20 generates target light Po having a desired time waveform. At this time, by placing the optical stopper 59 in the waveform generation unit 20 at a predetermined position on the optical path, it is possible to prevent the emission of a reference single optical pulse Pr from the waveform generation unit 20. In addition, during light irradiation, a mirror 92 is inserted in the optical path between the waveform generation unit 20 and the measurement unit 30. As a result, the target light Po emitted from the waveform generation unit 20 can be guided to the light irradiation unit 93. The light irradiation unit 93 is, for example, a focusing optical element such as an objective lens or a focusing lens, which focuses the target light Po onto or inside the object S.

[0083] The light irradiation device 2 may not only irradiate light but also be a laser processing device that processes the target object S. The laser processing device processes the target object S by focusing and irradiating the surface or interior of the target object S with target light Po, which has a desired time waveform, using the light irradiation unit 93. In this case, it is preferable that the light source 10 is a laser light source.

[0084] The light irradiation device 2 may be used together with the light detection unit 94. An observation device comprising the light irradiation device 2 and the light detection unit 94 can observe the object S by focusing and irradiating the surface or interior of the object S with target light Po, which has a desired time waveform, using the light irradiation unit 93, and detecting the light from the object S due to the light irradiation with the light detection unit 94.

[0085] Figure 14 is a flowchart illustrating an example of a light irradiation method using the light irradiation device 2. The waveform generation step S11, measurement step S12, and calculation step S13 are the same as those described in Figure 12. In the determination step S14, it is determined whether the time waveform of the target light Po obtained in the calculation step S13 is the desired time waveform. If the determination step S14 determines that the time waveform of the target light Po is not the desired time waveform, in the light control step S15, the time waveform of the target light Po generated in the waveform generation step S11 is controlled so that the time waveform of the target light Po obtained in the calculation step S13 becomes the desired time waveform. These steps are repeated. If the determination step S14 determines that the time waveform of the target light Po is the desired time waveform, in the light irradiation step S16, the target light Po is irradiated onto the target object S. At this time, the light stopper 59 may be placed on a predetermined optical path to block the reference single light pulse Pr. Furthermore, the target optical fiber Po and the reference single optical pulse Pr generated in the waveform generation step S11 are separated from each other by a time interval longer than the time width of either the target optical fiber Po or the time width of the reference single optical pulse Pr.

[0086] Thus, the light irradiation device 2 and the light irradiation method allow for the irradiation of an object S with a target light Po having a desired time waveform. For example, if the light irradiation device 2 is part of a laser processing device, the target light Po, which has a time waveform optimized for processing the object S such as a metal plate or semiconductor wafer, can be focused onto or inside the object S, leading to improved processing accuracy. Also, if the light irradiation device 2 is part of a microscope, the target light Po, which has a time waveform optimized for observing the object S such as a biological sample such as cells, can be focused onto or inside the object S, leading to improved observation accuracy.

[0087] Figure 15 is a flowchart showing an example of a laser processing method using a laser processing apparatus. The waveform generation step S11, measurement step S12, calculation step S13, determination step S14, and optical control step S15 are the same as those described in Figure 14. However, it is preferable that the optical pulse output from the light source 10 is laser light. If it is determined in the determination step S14 that the time waveform of the target optical light Po is a desired time waveform, in the processing step S17, the target optical light Po is focused onto or inside the target object S to process the target object S. At this time, an optical stopper 59 may be placed on a predetermined optical path to block the reference single optical pulse Pr. Note that the target optical light Po and the reference single optical pulse Pr generated in the waveform generation step S11 are separated from each other by a time interval longer than the time width of the target optical light Po and the time width of the reference single optical pulse Pr.

[0088] Figure 16 is a flowchart illustrating an example of an observation method using a microscope. The waveform generation step S11, measurement step S12, calculation step S13, determination step S14, light control step S15, and light irradiation step S16 are the same as those described in Figure 14. In the light detection step S18, light from the object S (e.g., fluorescence, reflected light, transmitted light, scattered light, etc.) generated by the light focusing in the light irradiation step S16 is detected by a photodetector (e.g., a point sensor, line sensor, or area sensor). Note that the target light Po and the reference single light pulse Pr generated in the waveform generation step S11 are separated from each other by a time interval longer than the time width of either the target light Po or the reference single light pulse Pr. [Explanation of Symbols]

[0089] 1…Optical waveform measuring device, 2…Optical irradiation device (laser processing device, observation device), 10…Light source, 20, 20A~20D…Waveform generation unit, 30…Measurement unit, 31…Beam splitter, 32a~32f…Mirror, 33…Stage, 34…Nonlinear optical element, 35…Photodetector, 40…Calculation unit, 51…Diffraction grating, 52, 53…Lens, 54…Spatial light modulator, 55…Mirror, 56…Half mirror, 57…Mirror, 58…Polarizing beam splitter 59... Light stopper, 61... Mirror, 62, 63... Half-wave plate, 64... Polarizer, 71... Half-wave plate, 72... Polarizing beam splitter, 73... Half-wave plate, 74... Diffraction grating, 75... Lens, 76... Spatial light modulator, 77... Mirror, 78... Half-wave plate, 79... Mirror, 81... Polarizing beam splitter, 82... Half-wave plate, 83... Polarizing beam splitter, 91... Control unit, 92... Mirror, 93... Light irradiation unit, S... Target object.

Claims

1. A device for measuring the time waveform of target light, A waveform generation unit generates and outputs the target light and a reference single light pulse based on the light pulse output from the light source, A measuring unit inputs the target light and the reference single light pulse at a time interval longer than the time width of the target light and the time width of the reference single light pulse, and measures the shape of the autocorrelation of the time waveform of the light including the target light and the reference single light pulse. A calculation unit that determines the time waveform of the target light based on the portion of the autocorrelation shape measured by the measurement unit that represents the cross-correlation between the time waveform of the target light and the time waveform of the reference single optical pulse, An optical waveform measuring device equipped with the following features.

2. The waveform generation unit, A dispersive element that outputs each wavelength component of the light pulse output from the light source in a direction corresponding to the wavelength, A spatial light modulator receives light of each wavelength component output from the dispersion element, spatially modulates it to generate the target light and the reference single optical pulse, Equipped with, The optical waveform measuring device according to claim 1.

3. The waveform generation unit, A dispersive element that outputs each wavelength component of the light pulse output from the light source in a direction corresponding to the wavelength, A spatial light modulator that takes light of each wavelength component output from the aforementioned dispersion element as input, spatially modulates the linearly polarized component of the first direction as input to generate the target light, and uses the linearly polarized component of the second direction unmodulated as the reference single light pulse, Equipped with, The optical waveform measuring device according to claim 1.

4. The waveform generation unit, A diffraction grating that outputs each wavelength component of the light pulse output from the light source in a direction corresponding to the wavelength, A spatial light modulator that receives light of each wavelength component diffracted and output by the diffraction grating and spatially modulates it to generate the target light, Equipped with, The zeroth-order light generated by the diffraction grating is defined as the reference single-light pulse. The optical waveform measuring device according to claim 1.

5. The waveform generation unit, A branching unit that splits the light pulse output from the light source into two and outputs a first branched light pulse and a second branched light pulse, A dispersive element that outputs each wavelength component of the first branched optical pulse in a direction corresponding to the wavelength, A spatial light modulator that receives light of each wavelength component output from the aforementioned dispersive element, spatially modulates it, and generates the target light; Equipped with, The second branched optical pulse is defined as the reference single optical pulse. The optical waveform measuring device according to claim 1.

6. The waveform generation unit, The system further includes an optical stopper for blocking the aforementioned reference single optical pulse. The optical waveform measuring device according to claim 1.

7. A light waveform measuring device according to any one of claims 1 to 6, A control unit controls the waveform generation unit so that the time waveform of the target light obtained by the calculation unit becomes a desired time waveform, A light irradiation unit that irradiates an object with the target light output from the waveform generation unit, A light irradiation device equipped with the following features.

8. The light irradiation device is provided as described in claim 7, The aforementioned light source is a laser light source. Laser processing equipment.

9. The light irradiation device according to claim 7, A light detection unit that detects light from the object due to light irradiation, An observation device equipped with the following features.

10. A method for measuring the time waveform of target light, A waveform generation step in which the target light and a reference single light pulse are generated and output based on the light pulse output from the light source, A measurement step of measuring the shape of the autocorrelation of the time waveform of light including the target light and the reference single light pulse, The measurement step includes a calculation step of determining the time waveform of the target light based on the portion of the shape of the autocorrelation measured in the measurement step that represents the cross-correlation between the time waveform of the target light and the time waveform of the reference single optical pulse, The target light and the reference single light pulse are separated from each other by a time interval longer than the time width of the target light and the time width of the reference single light pulse. Optical waveform measurement method.

11. A method of irradiating an object with target light, A waveform generation step in which the target light and a reference single light pulse are generated and output based on the light pulse output from the light source, A measurement step of measuring the shape of the autocorrelation of the time waveform of light including the target light and the reference single light pulse, A calculation step to determine the time waveform of the target light based on the portion of the shape of the autocorrelation measured in the measurement step that represents the cross-correlation between the time waveform of the target light and the time waveform of the reference single optical pulse, A light control step that controls the time waveform of the target light generated by the waveform generation step so that the time waveform of the target light obtained in the calculation step becomes a desired time waveform, The system comprises an irradiation step of irradiating an object with the target light controlled in the light control step and generated in the waveform generation step, The target light and the reference single light pulse are separated from each other by a time interval longer than the time width of the target light and the time width of the reference single light pulse. Light irradiation method.

12. A method of processing an object using target light, A waveform generation step in which a target light and a reference single light pulse are generated and output based on a laser light pulse output from a light source, A measurement step of measuring the shape of the autocorrelation of the time waveform of light including the target light and the reference single light pulse, A calculation step to determine the time waveform of the target light based on the portion of the shape of the autocorrelation measured in the measurement step that represents the cross-correlation between the time waveform of the target light and the time waveform of the reference single optical pulse, A light control step that controls the time waveform of the target light generated by the waveform generation step so that the time waveform of the target light obtained in the calculation step becomes a desired time waveform, The process includes a processing step in which the target light controlled in the light control step and generated in the waveform generation step is focused onto or inside the target object to process the object, The target light and the reference single light pulse are separated from each other by a time interval longer than the time width of the target light and the time width of the reference single light pulse. Laser processing method.

13. A method of observing an object, A waveform generation step that generates and outputs target light and a reference single light pulse based on the light pulse output from the light source, A measurement step of measuring the shape of the autocorrelation of the time waveform of light including the target light and the reference single light pulse, A calculation step to determine the time waveform of the target light based on the portion of the shape of the autocorrelation measured in the measurement step that represents the cross-correlation between the time waveform of the target light and the time waveform of the reference single optical pulse, A light control step that controls the time waveform of the target light generated by the waveform generation step so that the time waveform of the target light obtained in the calculation step becomes a desired time waveform, A light irradiation step in which the target light controlled in the light control step and generated in the waveform generation step is focused onto or inside the target object, The light detection step includes detecting the light that is focused in the light irradiation step and generated on the object, The target light and the reference single light pulse are separated from each other by a time interval longer than the time width of the target light and the time width of the reference single light pulse. Observation method.

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