Optical device, optical processing device, microscope device, and scanning method

Abstract

An optical device (10) of an optical processing device (1) is provided with: an optical fiber amplifier that amplifies pulsed light; a diffraction grating (12) that disperses the pulsed light (PL) output from the fiber amplifier by a diffraction phenomenon; a collimator lens (13) that parallels the pulsed light (PL) dispersed by the diffraction grating (12); and an objective lens (17) that focuses the pulsed light (PL) that has passed through the collimator lens (13), and by changing the magnification of the fiber amplifier, the position at which the temporal focus occurs is changed in the direction of the optical axis of the objective lens (17).

Description

Technical Field

[0001] The present invention relates to an optical device, an optical processing device, a microscope device, and a scanning method. Background Art

[0002] Some optical processing devices or microscopes include an optical device that outputs pulsed light. In order to improve the resolution of a microscope that includes an optical device that outputs pulsed light, a technique called temporal focus is known (for example, see Non-Patent Document 1).

[0003] Prior art literature

[0004] Non-patent literature

[0005] Non-patent literature 1: Durst E. He, Simultaneous spatial and temporal focusing for axial scanning, Optics Express, 2006, 14, 12243 Summary of the invention

[0006] The optical device of the present invention comprises: an amplifier for amplifying pulsed light; a dispersion element for dispersing the pulsed light output from the amplifier; and an objective lens for focusing the pulsed light dispersed in the dispersion element, and the optical device is capable of changing the amplification factor of the amplifier.

[0007] The optical processing device of the present invention includes an optical device for scanning pulse light irradiated onto a workpiece, and the optical device is the above-mentioned optical device.

[0008] The microscope apparatus of the present invention includes an optical device for scanning pulse light irradiated onto a sample, and the optical device is the optical device described above.

[0009] The scanning method of the present invention includes: using an amplifier to amplify pulse light; using a dispersion element to disperse the pulse light output from the amplifier; and using an objective lens to focus the pulse light dispersed in the dispersion element, and by changing the amplification factor of the amplifier, the position of the generation time focus of the pulse light focused by the objective lens is changed in the direction of the optical axis of the objective lens to perform scanning. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a diagram schematically showing the configuration of an optical processing device including an optical device according to the first embodiment.

[0011] Figure 2 This is a schematic diagram showing an example of an optical system utilizing time focusing.

[0012] Figure 3 This is a graph showing the relationship between the pulse time width of the pulse light output from the optical fiber amplifier and the average output of the optical fiber amplifier.

[0013] Figure 4 This is a graph showing the relationship between the spectral width of pulse light output from an optical fiber amplifier and the average output of the optical fiber amplifier.

[0014] Figure 5 This is a graph showing the relationship between the chirp amount (GDD) of pulse light output from an optical fiber amplifier and the average output of the optical fiber amplifier.

[0015] Figure 6 This is a schematic diagram of the light source unit.

[0016] Figure 7 is a top view of the compressor.

[0017] Figure 8 is a side view of the compressor.

[0018] Fig. 9 This is a graph showing the compression characteristics of the pulse time width of pulse light output from the optical fiber amplifier.

[0019] Fig.10 : is a flowchart showing the flow of the scanning method based on pulse light.

[0020] Fig.11 It is a schematic configuration diagram of a light source unit according to a modified example.

[0021] Fig.12 It is a top view of a compressor according to a modified example.

[0022] Fig.13 It is a schematic structural diagram of an optical device according to a modified example.

[0023] Fig.14 This is a graph showing the compression characteristics of the pulse time width of pulse light in the optical device according to the modification.

[0024] Fig.15 This is a schematic configuration diagram showing a microscope device having an optical device according to a second embodiment. DETAILED DESCRIPTION

[0025] The following describes a preferred embodiment of the present invention. Figure 1 The optical processing device according to the first embodiment will be described. Figure 1As shown, the optical processing device 1 of the first embodiment includes a stage 5, an optical device 10, and an observation unit 60. The optical processing device 1 controls the optical device 10 or the stage 5, etc. based on processing data created according to the desired shape, thereby being able to process the workpiece W as the processing object into the desired shape. The workpiece W is placed on the upper surface of the stage 5. The material of the workpiece W can be, for example, metal, resin, or glass. In addition, the stage 5 can be configured to be able to displace the workpiece W placed on the upper surface of the stage 5 at least in a direction perpendicular to the optical axis of the optical processing device 1. The position of the workpiece W is adjusted by driving the stage 5, so that the pulse light from the optical device 10 can be irradiated even at a position exceeding the scanning width of the optical device 10 described later.

[0026] The observation unit 60 has an illumination light source 61, a half mirror 62, an imaging lens 63, and an imaging unit 64. Furthermore, the observation unit 60 includes the dichroic mirror 15 and the objective lens 17 of the optical device 10. The illumination light source 61 is configured using an LED (Light Emitting Diode) or the like. The illumination light source 61 emits illumination light in the wavelength range of visible light. The half mirror 62 reflects a portion of the illumination light emitted from the illumination light source 61 toward the dichroic mirror 15. The half mirror 62 transmits the light from the workpiece W reflected by the dichroic mirror 15 toward the imaging lens 63. The ratio of the transmittance to the reflectance of the half mirror 62 is set to 1:1, for example. The imaging lens 63 images the light from the workpiece W that has passed through the half mirror 62. The imaging unit 64 is configured using an imaging element such as a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor). The imaging unit 64 captures the image of the workpiece W formed by the imaging lens 63 .

[0027] The image of the workpiece W captured by the imaging unit 64 is displayed on a display device (not shown). The workpiece W can be observed by the image displayed on the display device. In addition, the control amount of the optical device 10 and the stage 5 by the control device (not shown) can be corrected based on the image data of the workpiece W captured by the imaging unit 64.

[0028] Next, the optical device 10 will be described. The optical device 10 focuses (converges) pulsed light PL on the workpiece W. The pulse time width of the pulsed light PL is, for example, a time width of the femtosecond (fs) order. This type of pulsed light PL is also called ultrashort pulsed light, but is referred to simply as "pulsed light" in the following description. In order to improve the resolution in the optical axis direction of the optical processing device 1 and the microscope device 201 described later, a technology called time focusing is used. In the following description, the technology called time focusing is sometimes referred to simply as "time focusing." In addition, the optical axis direction of the optical processing device 1 (or microscope device 101) having the optical device 10 is sometimes referred to as the z direction, and the directions perpendicular to the optical axis are sometimes referred to as the x direction and the y direction. For example, Figure 2 , Figure 7 , Figure 8 , Fig.11 The directions indicated by arrows are respectively referred to as x-direction, y-direction, and z-direction.

[0029] Here, consider the case where pulsed light is focused on an object surface (for example, the processed surface of a workpiece W). Let the focusing radius of the pulsed light be w, the wave number of the pulsed light be k, and the wavelength of the pulsed light be λ. In this case, the beam diameter of the pulsed light becomes a roughly fixed range in the z direction, that is, the confocal length is kw. 2 =2πw 2 / λ. If the focusing radius w of the pulsed light is reduced, the confocal length becomes shorter, and the resolution of the optical axis direction (z direction) of the optical processing device becomes higher. For example, if the wavelength λ of the pulsed light is set to 1μm, if the focusing radius w of the pulsed light is reduced to about 1μm, the area with high light intensity of the pulsed light (i.e., the confocal length) is a limited area of ​​about 6μm in the z direction. Assuming that the focusing radius w of the pulsed light is increased to about 50μm, the confocal length is about 16mm, and the resolution of the optical axis direction (z direction) of the optical processing device becomes lower.

[0030] A technique called time focusing has been proposed, in which the resolution in the optical axis direction (z direction) can be improved even if the focusing radius w of the pulse light is increased. Figure 2 An example of an optical system using time focusing is shown in FIG. Figure 2 In the figure, the diffraction grating 510 disperses the pulse light PL emitted from the light source unit (not shown) by the diffraction phenomenon. The pulse light PL dispersed in the diffraction grating 510 is incident on the collimating lens 520. The pulse light PL transmitted through the collimating lens 520 becomes parallel light and is incident on the objective lens 530. The pulse light PL transmitted through the objective lens 530 is focused on the object plane OB arranged at the focus of the objective lens 530. In addition, in the following description, the object plane OB is the processed surface unless otherwise specified.

[0031] In addition, the diffraction grating 510 and the object plane OB are conjugated with each other. As the pulse light PL dispersed in the diffraction grating 510 approaches the collimating lens 520, the pulse time width of the pulse light PL becomes larger. Then, when the pulse light PL transmits the collimating lens 520 and the objective lens 530 and reaches the object plane OB conjugated with the diffraction grating 510, the pulse time width of the pulse light PL becomes smaller, and the original pulse time width when it is incident on the diffraction grating 510 is reproduced. This phenomenon is called time focusing. At a position deviating from the object plane OB in the z direction, the pulse time width of the pulse light PL becomes relatively larger, so the peak power of the pulse light PL decreases, and the processing efficiency using the pulse light PL decreases. As a result, the resolution in the optical axis direction (z direction) of the optical processing device can be improved.

[0032] exist Figure 2 In the illustrated optical system using time focusing, the pulse time width of the pulse light PL near the object plane OB is approximately expressed by the following equation (1).

[0033] [Number 1]

[0034]

[0035] Here, τ 0 represents the pulse time width of the pulse light PL when the pulse light PL is a Fourier transform limited pulse, that is, when there is no chirp and GDD (Group Delay Dispersion) = 0. Here, it is assumed that the pulse light PL of the Fourier transform limited pulse is incident on the diffraction grating 510. In addition, z R It can be approximately expressed by the following formula (2).

[0036] [Number 2]

[0037]

[0038] Here, f represents the focal length of the objective lens 530. 0Represents the wave number at the center frequency in the spectrum of the pulsed light PL after dispersion in the diffraction grating 510. The coordinate in the x direction of the incident position of the monochromatic wave with a frequency ω in the spectrum of the pulsed light PL relative to the objective lens 530 is expressed by x=αω. In addition, with respect to the frequency ω, an offset is set in such a way that the center frequency in the spectrum of the pulsed light PL becomes zero (0). α is a coefficient determined by the dispersion (or line density, incident angle) of the diffraction grating 510, the focal length fc of the collimating lens 520, and the like. Ω is the maximum frequency in the spectrum of the pulsed light PL. The width of the pulsed light PL in the x direction relative to the incident position of the objective lens 530 (i.e., the width in the dispersion direction of the pulsed light PL after dispersion in the diffraction grating 510) is approximately 2αΩ. Here, regarding the diameter s of the monochromatic wave in the spectrum of the pulsed light PL (refer to Figure 2 ), set to s<<αΩ.

[0039] In addition, the position z=0 corresponds to the conjugate position of the diffraction grating 510. From the formula (1), it can be seen that if z=0, the pulse time width of the pulse light PL is the smallest. If z>z R , the pulse time width of the pulse light PL becomes significantly larger. Therefore, if z>z R , the pulse time width of the pulse light PL becomes larger and the peak power of the pulse light PL decreases. Therefore, the resolution of the optical processing device in the optical axis direction (z direction) can be said to be z R For example, when f = 10 mm, αΩ = 3 mm, and λ = 1 μm, z R About 3μm. That is, assuming that the focusing radius w of the pulse light is set to about 50μm, the resolution of the optical processing device in the z direction is also at the μm level due to the effect of time focusing. In this way, due to the effect of time focusing, even if the focusing radius of the pulse light is increased, the resolution in the optical axis direction (z direction) of the optical processing device becomes higher, so it is possible to perform fine processing such as removal processing relative to the workpiece. In addition, when the material of the workpiece is a transparent resin or glass, it is possible to perform fine processing relative to the inside of the workpiece due to the effect of time focusing. By setting the peak power of the pulse light at the position z=0 to near the processing threshold at which processing relative to the workpiece can be performed, the resolution in the optical axis direction (processing resolution) of the optical processing device can be further improved.

[0040] The position in the z direction where temporal focusing occurs can be changed by chirping the pulsed light PL (changing the frequency over time). The chirp amount is calculated using GDD (fs 2 Or ps 2 The relationship between the chirp amount β and the change Δz in the position in the z direction that produces temporal focusing is approximately expressed by the following equation (3).

[0041] [Number 3]

[0042] Δz≈βΩ 2 z R …(3)

[0043] Here, β = GDD / 2. For example, at β = 10000fs 2 (GDD = 20000fs 2 ), z R When Δz is 0.1 to 10 μm and Ω is 0.033 rad / fs (corresponding to pulse light of 70 fs), Δz is 110 μm.

[0044] In order to chirp the pulse light of the Fourier transform-limited pulse, there are methods such as using quartz or other nitrate materials, or using prism pairs, diffraction grating pairs (grating pairs), etc. In the case of using a prism pair, the GDD of the pulse light can be changed by changing the spacing between the prisms, or the degree to which the prism is inserted into the light path. In the case of using a diffraction grating pair (grating pair), the GDD of the pulse light can be changed by changing the spacing between the diffraction gratings. In the document "Durst E. He, Simultaneous spatial and temporal focusing for axial scanning, Optics Express, 2006, 14, 12243", it is experimentally shown that by adjusting the prism pair, the GDD can be changed by 11000 fs. 2 The position where the time focus is generated can be changed by about 140 μm. In this method, since the position of the prism is mechanically changed, it takes time to change the position where the time focus is generated. In this embodiment, a light source unit using an optical fiber amplifier and an optical system using time focus are combined to change the position where the time focus is generated at a high speed.

[0045] Fiber amplifiers are made of optical fibers with a length of about 1m to several tens of meters. The core diameter of the optical fiber is about several μm to several tens of μm. Since such a thin and long optical fiber with a small core diameter is used, the dispersion and nonlinearity in the fiber amplifier are large. When a fiber amplifier is used to amplify pulse light, the pulse time width and spectral width of the pulse light output from the fiber amplifier change according to the amplification factor of the fiber amplifier. The chirp (GDD) of the pulse light is roughly proportional to the "pulse time width / spectral width (ps / nm)". In addition, ps / nm is proportional to ps 2 For example, for a pulse light with a central wavelength of 1.06 μm, ps / nm = -1.68 ps 2The relationship between the pulse time width of the pulsed light and the amplification factor of the optical fiber amplifier is generally different. Therefore, it is expected that the chirp (GDD) of the pulsed light will change in accordance with the amplification factor of the optical fiber amplifier.

[0046] Figure 3 The figure shows the relationship between the pulse time width of the pulse light output from the optical fiber amplifier and the average output of the optical fiber amplifier. Figure 4 The relationship between the spectral width of the pulsed light output from the fiber amplifier and the average output of the fiber amplifier is shown. Figure 3 as well as Figure 4 In the graph shown, as the input to the optical fiber amplifier, a pulse light with a period of 350 fs and a wavelength of 1.56 μm is used. As the optical fiber amplifier, an erbium doped fiber amplifier (EDFA) with a length of ~16 m, a mode field diameter (MFD) of ~5 μm, and normal dispersion is used. The average output of the optical fiber amplifier is proportional to the pulse energy (energy per pulse) of the pulse light. According to Figure 3 as well as Figure 4 It can be seen that the increase ratio of the spectrum width when the pulse energy is increased is greater than the increase ratio of the average output of the optical fiber amplifier, that is, the increase ratio of the pulse time width when the pulse energy is increased.

[0047] Figure 5 Shown from Figure 3 as well as Figure 4 The relationship between the chirp amount (GDD) of the pulse light output from the optical fiber amplifier and the average output of the optical fiber amplifier is obtained. Figure 5 The average output of the optical fiber amplifier, i.e., the chirp amount (GDD) of the pulse light output from the optical fiber amplifier varies with the pulse energy. 2 (170000~200000fs 2 ) within the range of .

[0048] like Figure 1 As shown, the optical device 10 of the first embodiment includes a light source unit 20, a first reflector 11, a diffraction grating 12, a collimating lens 13, a second reflector 14, a dichroic mirror 15, and an objective lens 17. The light source unit 20 emits, for example, a pulse light PL in a wavelength range of 1 μm. The first reflector 11 reflects the pulse light PL emitted from the light source unit 20 toward the diffraction grating 12. The diffraction grating 12 disperses the pulse light PL reflected by the first reflector 11 through a diffraction phenomenon. The collimating lens 13 makes the pulse light PL dispersed in the diffraction grating 12 parallel.

[0049] The second reflector 14 reflects the pulse light PL transmitted through the collimating lens 13 toward the dichroic mirror 15. In addition, a galvano mirror (not shown) that reflects the pulse light PL transmitted through the collimating lens 13 toward the dichroic mirror 15 may be provided instead of the second reflector 14. The galvano mirror can change the direction of travel of the pulse light PL by changing the direction of the reflection surface. By using the galvano mirror to change the direction of travel of the pulse light PL, it is possible to scan in a plane (processed surface) perpendicular to the optical axis of the objective lens 17 in the workpiece W. The galvano mirror is preferably provided at the position of the pupil of the objective lens 17 or at a position conjugate with the pupil.

[0050] The dichroic mirror 15 transmits the pulse light PL incident on the dichroic mirror 15 toward the objective lens 17. In addition, the dichroic mirror 15 reflects the illumination light from the observation unit 60 (half mirror 62) incident on the dichroic mirror 15 toward the objective lens 17. The dichroic mirror 15 reflects the light (visible light) from the workpiece W incident on the dichroic mirror 15 via the objective lens 17 toward the observation unit 60 (half mirror 62).

[0051] The objective lens 17 focuses the pulse light PL transmitted through the dichroic mirror 15 on the workpiece W. In addition, the diffraction grating 12 and the workpiece W (processed surface) are conjugate with each other. In addition, the objective lens 17 irradiates the illumination light reflected by the dichroic mirror 15 to the workpiece W. The light from the workpiece W irradiated with the illumination light enters the objective lens 17. The light (visible light) from the workpiece W incident on the objective lens 17 passes through the objective lens 17 and is reflected by the dichroic mirror 15.

[0052] Next, refer to Figure 6 to Figure 8 The light source unit 20 is described. Figure 6 As shown, the light source unit 20 has an oscillator 22, a first optical isolator 23, a second optical isolator 24, a first optical fiber amplifier 25, a second optical fiber amplifier 26, a collimating lens 29, and a compressor 31. The oscillator 22 is constructed using a mode-locked fiber laser. The oscillator 22 generates a Fourier transform-limited pulse, i.e., a pulse light, having a pulse time width of about 100 fs to 1 ps. The first optical isolator 23 is provided between the oscillator 22 and the first optical fiber amplifier 25. The second optical isolator 24 is provided between the first optical fiber amplifier 25 and the second optical fiber amplifier 26. The first optical isolator 23 and the second optical isolator 24 transmit only the pulse light traveling in the forward direction and block the light traveling in the reverse direction.

[0053] The first fiber amplifier 25 is constructed using an erbium doped fiber amplifier (EDFA) with normal dispersion. The first fiber amplifier 25 can also be constructed using an ytterbium doped fiber amplifier (YDFA) with normal dispersion. A first pump LD (laser diode) 27 is provided in the first fiber amplifier 25. The first pump LD 27 allows excitation light (also called pump light) to be incident on the first fiber amplifier 25. The first fiber amplifier 25 amplifies the pulse light generated from the oscillator 22 using the excitation light incident from the first pump LD 27. By changing the pump current of the first pump LD 27, the amplification factor (i.e., output) of the first fiber amplifier 25 can be changed. The first fiber amplifier 25 is a slender fiber amplifier with a smaller core diameter than the second fiber amplifier 26. Thus, the chirp characteristics (GDD) of the pulse light are determined by the first fiber amplifier 25 with relatively large dispersion and nonlinearity.

[0054] The second fiber amplifier 26 is configured using an erbium-doped fiber amplifier (EDFA). The second fiber amplifier 26 may also be configured using an ytterbium-doped fiber amplifier (YDFA). A second pump LD (laser diode) 28 is provided in the second fiber amplifier 26. The second pump LD 28 allows excitation light (also referred to as pump light) to be incident on the second fiber amplifier 26. The second fiber amplifier 26 amplifies the pulse light output from the first fiber amplifier 25 using the excitation light incident from the second pump LD 28. By changing the pump current of the second pump LD 28, the amplification factor (i.e., output) of the second fiber amplifier 26 can be changed. The second fiber amplifier 26 is a fiber amplifier that is shorter than the first fiber amplifier 25 and has a larger core diameter. Thus, the output (pulse energy of pulse light) is determined by using the second fiber amplifier 26 with relatively small dispersion and nonlinearity.

[0055] By using the first optical fiber amplifier 25 with relatively large dispersion and nonlinearity and the second optical fiber amplifier 26 with relatively small dispersion and nonlinearity as amplifiers, it is possible to reduce the variation of the pulse energy of the pulse light while changing the chirp amount (GDD) of the pulse light output from the amplifiers (the first optical fiber amplifier 25 and the second optical fiber amplifier 26). In addition, a solid-state amplifier may be provided as the second amplifier instead of the second optical fiber amplifier 26. Moreover, in the case where a large pulse energy is required, a third amplifier may be provided after the second amplifier. In addition, in the case where the variation of the pulse energy accompanying the variation of the chirp amount (GDD) of the pulse light can be allowed, the second optical fiber amplifier 26 may be omitted. In this case, in the following description, the output of the second optical fiber amplifier 26 may be understood as the output of the first optical fiber amplifier 25.

[0056] The collimator lens 29 collimates the pulse light output from the second optical fiber amplifier 26. The compressor 31 compresses the pulse time width of the pulse light output from the second optical fiber amplifier 26 and transmitted through the collimator lens 29, and emits the pulse light PL which is a Fourier transform limited pulse.

[0057] For example Figure 7 as well as Figure 8 As shown, the compressor 31 includes an output reflector 32, a diffraction grating pair of a first diffraction grating 33 and a second diffraction grating 34, and a roof reflector 35. The pulse light transmitted through the collimating lens 29 passes through a position deviated in the -y direction perpendicular to the optical axis from the output reflector 32. The pulse light that has passed through the output reflector 32 is spatially dispersed by the first diffraction grating 33 and the second diffraction grating 34. The pulse light dispersed by the first diffraction grating 33 and the second diffraction grating 34 is reflected by the roof reflector 35 and returns in the order of the second diffraction grating 34 and the first diffraction grating 33. The pulse light that returns in the order of the second diffraction grating 34 and the first diffraction grating 33 is deviated in the +y direction by the roof reflector 35, and therefore, is reflected by the output reflector 32 and emitted to the outside (the first reflector 11). Such a compressor 31 has negative dispersion (GDD<0), and the dispersion of the compressor 31 can be changed by changing the interval between the first diffraction grating 33 and the second diffraction grating 34 .

[0058] Fig. 9 Shown from Figure 6 FIG. 2 shows the compression characteristics of the pulse time width of the pulse light output by the amplifier having a two-stage structure (the first optical fiber amplifier 25 and the second optical fiber amplifier 26 ). Fig. 9 The horizontal axis of the graph shown represents the dispersion amount (ps) of the compressor 31 having a diffraction grating pair disposed after the first optical fiber amplifier 25 and the second optical fiber amplifier 26. 2 =10 6 fs 2 ), the vertical axis represents the pulse time width (fs) of the pulse light. Fig. 9 The ▲ mark in the graph shown represents the compression characteristics when the pump current of the first pump LD 27 in the first optical fiber amplifier 25 is 600 mA. Fig. 9 The ■ mark in the graph shows the compression characteristics when the pump current of the first pump LD 27 in the first optical fiber amplifier 25 is 1000 mA. In addition, when the pump current of the first pump LD 27 in the first optical fiber amplifier 25 is 600 mA or 1000 mA, the pump current of the second pump LD 28 in the second optical fiber amplifier 26 is fixed. When the pump current of the first pump LD 27 in the first optical fiber amplifier 25 is 600 mA, the dispersion amount of the compressor 31 for obtaining the minimum pulse time width is -0.163 ps.2 , that is, the chirp amount (GDD) of the pulse light is +0.163ps 2 When the pump current of the first pump LD 27 in the first optical fiber amplifier 25 is 1000 mA, the dispersion amount of the compressor 31 for obtaining the minimum pulse time width is -0.148 ps. 2 , that is, the chirp amount (GDD) of the pulse light is +0.148ps 2 It can be seen that by changing the pump current of the first pump LD27 in the first fiber amplifier 25 within the range of 600mA to 1000mA, the chirp amount (GDD) of the pulse light output from the two-stage amplifier (the first fiber amplifier 25 and the second fiber amplifier 26) can be changed by only 0.015ps. 2 =15000fs 2 .

[0059] In addition, when the pump current of the first pump LD27 in the first optical fiber amplifier 25 is 600mA, the output of the second optical fiber amplifier 26 is 477mW. When the pump current of the first pump LD27 in the first optical fiber amplifier 25 is 1000mA, the output of the second optical fiber amplifier 26 is 537mW. In this experiment, since the pump current of the second pump LD28 in the second optical fiber amplifier 26 is set to be fixed, the output of the second optical fiber amplifier 26 fluctuates slightly, but by adjusting the pump current of the second pump LD28, the output of the second optical fiber amplifier 26 can be maintained within a fixed range. In addition, when the pump current of the first pump LD27 in the first optical fiber amplifier 25 is either 600mA or 1000mA, the minimum pulse time width of the pulse light is almost the same (~115fs). As described above, according to Figure 6 The amplifier of the two-stage structure shown (the first optical fiber amplifier 25 and the second optical fiber amplifier 26) can change only the chirp amount (GDD) of the pulse light while keeping the pulse energy of the pulse light and the minimum pulse time width after compression substantially constant.

[0060] In addition, Figure 6 In the example of the two-stage amplifier (the first optical fiber amplifier 25 and the second optical fiber amplifier 26) shown in FIG. 1 , ΔGDD is 15000 fs. 2 , Ω~0.02rad / fs (corresponding to pulse light of ~115fs), therefore, according to the above formula (3), it becomes Δz~3×z R As explained by the above formula (2), z R The setting is performed using the coefficient α determined by the dispersion (or line density, incident angle) of the diffraction grating 12, the focal length fc of the collimating lens 13, the focal length f of the objective lens 17, and the like. Assuming that z is setR =10μm, the change Δz in the z-direction position where temporal focusing occurs becomes 30μm. That is, in the above example, by modulating the pump current of the first pump LD 27 between 600mA and 1000mA, the position where temporal focusing occurs can be scanned by changing 30μm in the optical axis direction (z-direction).

[0061] When the first fiber amplifier 25 and the second fiber amplifier 26 are erbium-doped fiber amplifiers (EDFA) or ytterbium-doped fiber amplifiers (YDFA), although it will also vary depending on the core diameter and the pumping state, the response of the modulated gain relative to the excitation light (pump light) of the first pump LD27 and the second pump LD28 (that is, the response of the modulated gain relative to the pump current) reaches ~10kHz in most cases. In other words, the gain of the first fiber amplifier 25 and the second fiber amplifier 26 can be changed at a high speed of ~10kHz. Based on the above experimental results, it means that the chirp amount (GDD) of the pulsed light can be changed at about ~10kHz. According to this method, compared with mechanical methods such as changing the position of the prism, the chirp amount (GDD) of the pulsed light can be simply changed at a high speed. In this way, by modulating the pump currents of the first pump LD27 and the second pump LD28 at high speed, the gain (amplification factor) of the first optical fiber amplifier 25 and the second optical fiber amplifier 26 can be changed at high speed, thereby enabling the chirp amount (GDD) of the pulsed light to be changed at high speed, the position where time focusing is generated to be changed at high speed, and scanning in the direction of the optical axis (z direction) to be performed at high speed.

[0062] Next, a scanning method using pulse light using the optical device 10 using the optical processing device 1 configured as described above will be described. Fig.10 1 is a flowchart showing the flow of the scanning method using pulse light. First, pulse light is generated by the oscillator 22 of the light source unit 20 (step ST1). At this time, the oscillator 22 generates pulse light which is a Fourier transform-limited pulse.

[0063] Next, the pulse light is amplified by the first optical fiber amplifier 25 and the second optical fiber amplifier 26 (step ST2). The pulse light generated by the oscillator 22 passes through the first optical isolator 23 and enters the first optical fiber amplifier 25. The first optical fiber amplifier 25 amplifies the pulse light generated by the oscillator 22. The pulse light output from the first optical fiber amplifier 25 passes through the second optical isolator 24 and enters the second optical fiber amplifier 26. The second optical fiber amplifier 26 amplifies the pulse light output from the first optical fiber amplifier 25. The pulse light output from the second optical fiber amplifier 26 passes through the collimating lens 29 and becomes parallel, and enters the compressor 31. The compressor 31 compresses the pulse time width of the pulse light transmitted through the collimating lens 29, and emits the Fourier transform limited pulse, that is, the pulse light PL.

[0064] Next, the pulse light is dispersed by the diffraction grating 12 (step ST3). The pulse light PL emitted from the compressor 31 of the light source unit 20 is reflected by the first reflector 11 and enters the diffraction grating 12. The diffraction grating 12 disperses the pulse light PL reflected by the first reflector 11 by the diffraction phenomenon. The pulse light PL dispersed in the diffraction grating 12 is transmitted through the collimating lens 13 and becomes parallel, and enters the second reflector 14. At this time, the spatial chirp of the pulse light PL required for temporal focusing is generated by the diffraction grating 12 and the collimating lens 13.

[0065] Next, the pulse light is focused by the objective lens 17 (step ST4). The pulse light PL reflected by the second reflector 14 passes through the dichroic mirror 15 and enters the objective lens 17. The objective lens 17 focuses the pulse light PL that has passed through the dichroic mirror 15 relative to the workpiece W. At this time, the pulse time width of the pulse light PL is reduced by the effect of time focusing, and the original pulse time width when it is incident on the diffraction grating 12 is reproduced on the processed surface of the workpiece W. For example, even if the focusing radius w of the pulse light PL is set to about 50 μm, the resolution in the optical axis direction (z direction) of the optical processing device 1 can be improved by the effect of time focusing, and fine processing such as removal processing can be performed relative to the workpiece W. In addition, when the material of the workpiece W is a transparent resin or glass, the effect of time focusing can be used to perform fine processing relative to the inside of the workpiece W. In addition, as described above, the pulse time width of the pulse light PL focused by the objective lens 17 becomes the pulse time width of the pulse light PL when it is incident on the diffraction grating 12 by generating time focusing. This includes the following cases: the pulse time width of the pulse light PL focused by the objective lens 17 becomes not only (completely) the same as the pulse time width of the pulse light PL when incident on the diffraction grating 12, but also approximately the same as the pulse time width of the pulse light PL when incident on the diffraction grating 12.

[0066] Then, the position where the temporal focus is generated is changed in the optical axis direction of the objective lens 17 to perform scanning (step ST5). At this time, the amplification factors of the first fiber amplifier 25 and the second fiber amplifier 26 are changed by modulating the pump currents of the first pump LD 27 and the second pump LD 28. Thus, the chirp amount (GDD) of the pulse light PL is changed, and the position where the temporal focus is generated is changed in the optical axis direction of the objective lens 17 to perform scanning in the optical axis direction (z direction). In addition, in a state where the pulse light PL from the optical device 10 is continuously irradiated with respect to the workpiece W, the above-mentioned step of generating pulse light (ST1), the step of amplifying pulse light (ST2), the step of dispersing pulse light (ST3), the step of focusing pulse light (ST4), and the step of scanning (ST5) are respectively performed in parallel.

[0067] According to the first embodiment, the optical device 10 of the optical processing device 1 includes the first fiber amplifier 25 and the second fiber amplifier 26 for amplifying pulsed light, the diffraction grating 12 for dispersing the pulsed light, and the objective lens 17 for focusing the pulsed light dispersed in the diffraction grating 12, and the amplification factors of the first fiber amplifier 25 and the second fiber amplifier 26 can be changed independently. In addition, the pulse time width of the pulsed light focused by the objective lens 17 becomes the pulse time width of the pulsed light when incident on the diffraction grating 12 by generating temporal focusing. As described above, by modulating the pump current of the first pump LD 27 at high speed, the amplification factor of the first fiber amplifier 25 can be changed at high speed, so that the chirp amount (GDD) of the pulsed light can be changed at high speed, and the position (position in the z direction) where temporal focusing is generated can be changed at high speed to perform scanning in the optical axis direction at high speed. In addition, due to the effect of time focusing, the resolution of the optical processing device 1 in the optical axis direction (z direction) becomes higher, so by changing the position (z direction position) where time focusing is generated at a high speed, fine processing such as removal processing can be performed at a high speed with respect to the workpiece W. In addition, by appropriately controlling the pump current of the second pump LD 28 to adjust the amplification factor of the second optical fiber amplifier 26, the chirp amount (GDD) of the pulse light can be changed while the change in the output of the pulse light can be suppressed within a fixed range.

[0068] In addition, a light quantity regulator such as an acousto-optic modulator (AOM) may be provided on the input side or output side of the second optical fiber amplifier 26 to control the pulse energy of the pulse light. In this way, the chirp amount (GDD) of the pulse light can be changed while reducing the variation of the pulse energy of the pulse light.

[0069] Furthermore, a compressor 31 may be provided for compressing the pulse time width of the pulse light output from the second optical fiber amplifier 26. In this way, a pulse light which is a Fourier transform-limited pulse can be obtained.

[0070] In the first embodiment described above, the oscillator 22 is provided, but the present invention is not limited thereto. For example, the oscillator 22 may not be provided, but the pulse light from the pulse light generator provided outside the optical processing device 1 may be amplified by the first optical fiber amplifier 25. In this case, the step (ST1) of generating the pulse light described above may be omitted.

[0071] In the first embodiment described above, the diffraction grating 12 is provided to disperse the pulse light by the diffraction phenomenon, but the present invention is not limited thereto. As a dispersive element to disperse the pulse light, a prism or the like may be provided in place of the diffraction grating 12. In addition, dispersing the pulse light by the dispersive element means that the optical path of the pulse light is spatially separated according to the wavelength of the pulse light.

[0072] In the first embodiment described above, the amplification factors of the first fiber amplifier 25 and the second fiber amplifier 26 are changed by modulating the pump currents of the first pump LD 27 and the second pump LD 28, but the present invention is not limited thereto. For example, the amplification factor of the first fiber amplifier 25 may be effectively changed by controlling the light amount of the input pulse light using an acousto-optic modulator (AOM) or the like provided at the input side of the first fiber amplifier 25, thereby changing the chirp amount (GDD) of the pulse light. In addition, the amplification factor of the second fiber amplifier 26 may be effectively changed by controlling the light amount of the pulse light using an acousto-optic modulator (AOM) or the like provided at the input side or the output side of the second fiber amplifier 26, thereby maintaining the output of the second fiber amplifier 26 within a fixed range.

[0073] In the first embodiment described above, the light source unit 20 has a two-stage amplifier (the first optical fiber amplifier 25 and the second optical fiber amplifier 26), but the invention is not limited thereto and may have only one amplifier. Fig.11 As shown, the light source unit 70 may also include an oscillator 22, an optical isolator 73, an optical fiber amplifier 75, a collimating lens 29, and a compressor 31. In addition, the optical isolator 73 is configured in the same manner as the first optical isolator 23 of the first embodiment. The optical fiber amplifier 75 is configured in the same manner as the first optical fiber amplifier 25 of the first embodiment. In addition, the collimating lens 29 makes the pulse light output from the optical fiber amplifier 75 parallel. A pump LD 77 is provided in the optical fiber amplifier 75. The pump LD 77 is configured in the same manner as the first pump LD 27 of the first embodiment, and the amplification factor (i.e., output) of the optical fiber amplifier 75 can be changed by changing the pump current of the pump LD 77. In addition, the oscillator 22 may not be provided, and the optical fiber amplifier 75 may be provided to amplify the pulse light from a pulse light generator provided outside the optical processing device.

[0074] In the first embodiment described above, the compressor 31 is formed using a diffraction grating pair (grating pair), but the present invention is not limited thereto and may also be formed using a prism pair. Fig.12 As shown, the compressor 131 may include an output reflector 32, a prism pair of a first prism 133 and a second prism 134, and a roof reflector 35. The pulse light transmitted through the collimating lens 29 passes through a position deviated in the -y direction perpendicular to the optical axis from the output reflector 32. The pulse light that has passed through the output reflector 32 is spatially dispersed by the first prism 133 and the second prism 134. The pulse light dispersed by the first prism 133 and the second prism 134 is reflected by the roof reflector 35 and returns in the order of the second prism 134 and the first prism 133. The pulse light that returns in the order of the second prism 134 and the first prism 133 is deviated in the +y direction by the roof reflector 35, and is therefore reflected by the output reflector 32 and emitted to the outside (the first reflector 11). This type of compressor 131 has negative dispersion (GDD<0), but the dispersion of the compressor 131 can be changed by changing the interval between the first prism 133 and the second prism 134 .

[0075] In the first embodiment described above, the compressor 31 is provided in the light source unit 20, but the present invention is not limited thereto, and the compressor may not be provided in the light source unit. Fig.13 As shown, the optical device 110 of the modified example includes a light source unit 120, a diffraction grating pair of a first diffraction grating 111 and a second diffraction grating 112, a reflection mirror 114, and an objective lens 117. The light source unit 120 includes an oscillator 122, an optical isolator 123, an optical fiber amplifier 125, and a collimating lens 129.

[0076] The oscillator 122 is constructed using a mode-locked fiber laser. The oscillator 122 generates pulse light, which is a Fourier transform-limited pulse with a pulse time width of about 100 fs to 1 ps. The optical isolator 123 is provided between the oscillator 122 and the fiber amplifier 125. The optical isolator 123 transmits only the pulse light traveling in the forward direction and blocks the light traveling in the reverse direction.

[0077] The optical fiber amplifier 125 is constructed using an erbium-doped fiber amplifier (EDFA) with normal dispersion. The optical fiber amplifier 125 can also be constructed using an ytterbium-doped fiber amplifier (YDFA) with normal dispersion. A pump LD (laser diode) 127 is provided in the optical fiber amplifier 125. The pump LD 127 allows excitation light (pump light) to be incident on the optical fiber amplifier 125. The optical fiber amplifier 125 amplifies the pulse light generated by the oscillator 122 using the excitation light incident from the pump LD 127. By changing the pump current of the pump LD 127, the amplification factor (i.e., output) of the optical fiber amplifier 125 can be changed. The collimating lens 129 makes the pulse light output from the optical fiber amplifier 125 parallel. In addition, the optical fiber amplifier can also be an amplifier of the two-stage structure of the first embodiment described above (the first optical fiber amplifier 25 and the second optical fiber amplifier 26). In addition, the oscillator 122 can be omitted, and the optical fiber amplifier can be set to amplify the pulse light from a pulse light generator provided outside the optical processing device.

[0078] The light source unit 120 emits a pulse light PL having a positive chirp via the optical fiber amplifier 125. The GDD of the pulse light PL emitted from the light source unit 120 is set to Dp, and Dp>0. The pulse light PL emitted from the light source unit 120 is spatially dispersed by passing through the first diffraction grating 111 and the second diffraction grating 112. The dispersion in the diffraction grating pair of the first diffraction grating 111 and the second diffraction grating 112 is set to Dg. At this time, the interval between the first diffraction grating 111 and the second diffraction grating 112 is adjusted in such a manner that Dg=-Dp. Spatial chirp is generated in the pulse light PL passing through the diffraction grating pair of the first diffraction grating 111 and the second diffraction grating 112. The pulse light PL that passes through the diffraction grating pair is spatially separated in frequency components, so although the GDD of the pulse light PL is 0 (i.e., Dp+Dg=0), it does not become the pulse time width of the Fourier transform-limited pulse. In a conventional compressor having a diffraction grating pair, the pulse light passes through the diffraction grating pair twice (double pass), so that spatial chirp is not generated and the pulse time width of the Fourier transform-limited pulse is obtained.

[0079] The pulse light PL passing through the diffraction grating pair of the first diffraction grating 111 and the second diffraction grating 112 is reflected by the reflector 114 and focused relative to the workpiece W by the objective lens 117. In addition, the dichroic mirror (not shown) of the first embodiment described above may be provided between the reflector 114 and the objective lens 117. By focusing the pulse light PL that has passed through the diffraction grating pair (the first diffraction grating 111 and the second diffraction grating 112) and has generated spatial chirp by the objective lens 117, a temporal focusing effect is obtained. That is, the pulse time width of the pulse light PL that has just passed through the objective lens 117 is the largest, and as it approaches the workpiece W (the focal plane of the objective lens 117), the pulse time width of the pulse light PL becomes smaller, and the pulse time width of the pulse light PL is the smallest at the processed surface of the workpiece W (the focal plane of the objective lens 117).

[0080] In the optical device 110 of the modified example, it can be said that the diffraction grating pair of the first diffraction grating 111 and the second diffraction grating 112 cancels the GDD of the pulse light PL emitted from the light source unit 120, and at the same time, gives the pulse light PL emitted from the light source unit 120 a spatial chirp required for temporal focusing. Thus, similarly to the first embodiment described above, by modulating the pump current of the pump LD 127 at high speed, the amplification factor of the optical fiber amplifier 125 can be changed at high speed, so that the chirp amount (GDD) of the pulse light can be changed at high speed, and the position (position in the z direction) where temporal focusing occurs can be changed at high speed. In addition, the resolution of the optical processing device in the optical axis direction (z direction) is increased by the effect of temporal focusing, so that the position (position in the z direction) where temporal focusing occurs can be changed at high speed, thereby enabling fine processing such as removal processing to be performed on the workpiece W at high resolution and high speed.

[0081] Fig.14 The compression characteristics of the pulse time width of the pulse light output from the optical fiber amplifier 125 of the optical device 110 according to the modification are shown. Fig.14 The horizontal axis of the graph shown in FIG. 1 represents the dispersion amount (fs ) of the diffraction grating pair (the first diffraction grating 111 and the second diffraction grating 112) disposed after the optical fiber amplifier 125 as a compressor. 2 ), the vertical axis represents the pulse time width (fs) of the pulse light. Fig.14 The compression characteristics of the compressor are achieved by using a two-pass compressor. Fig.14 The mark ◆ in the graph shows the compression characteristics when the pump current of the pump LD 127 in the optical fiber amplifier 125 is 1.0A. Fig.14 The square mark in the graph shows the compression characteristics when the pump current of the pump LD 127 in the optical fiber amplifier 125 is 2.8A. Fig.14The ▲ mark in the graph shows the compression characteristics when the pump current of the pump LD 127 in the optical fiber amplifier 125 is 5.0A.

[0082] When the pump current of the pump LD 127 in the fiber amplifier 125 is 1.0A, the output of the fiber amplifier 125 is 122mW. When the pump current of the pump LD 127 in the fiber amplifier 125 is 2.8A, the output of the fiber amplifier 125 is 918mW. When the pump current of the pump LD 127 in the fiber amplifier 125 is 5.0A, the output of the fiber amplifier 125 is 1970mW. Fig.14 It can be seen that by changing the output of the optical fiber amplifier 125 within the range of 100 mW to 2000 mW, the chirp amount (GDD) of the pulse light output from the optical fiber amplifier 125 can be changed by only about 48000 fs. 2 In addition, when the pump current of the pump LD 127 in the optical fiber amplifier 125 is 1.0A, 2.8A, or 5.0A, the minimum pulse time width of the pulse light is almost the same (~90fs). Fig.13 The modified example shown can change the chirp amount (GDD) of the pulse light while keeping the minimum pulse time width after compression of the pulse light substantially constant.

[0083] In the optical device 110 of the modified example, ΔGDD ≈ 48000 fs 2 , Ω~0.026rad / fs (corresponding to pulse light of ~90fs), therefore, according to the above formula (3), it becomes Δz~16×z R As in the first embodiment described above, it is assumed that z R =10μm, then the change Δz in the z-direction position resulting in time focusing is 160μm.

[0084] Next, refer to Fig.15 The microscope device according to the second embodiment of the present application is described below. Fig.15 As shown, the microscope device 201 of the second embodiment includes a stage 205, an optical device 210, and a detection unit 260. The microscope device 201 is also called a two-photon excitation fluorescence microscope or a multi-photon excitation fluorescence microscope. A sample SA is placed on the upper surface of the stage 205. The sample SA may be, for example, a cell.

[0085] The detection unit 260 has a condenser lens 261 and a detection unit 262. The detection unit 260 includes the dichroic mirror 215, the galvano mirrors 216, 216, and the objective lens 217 of the optical device 210. The condenser lens 261 condenses the fluorescence from the sample SA reflected by the dichroic mirror 215. The detection unit 262 is configured using a photomultiplier tube (PMT), a photodiode (PD), and the like. The detection unit 262 detects the fluorescence from the sample SA condensed by the condenser lens 261 and outputs a detection signal. Based on the detection signal detected by the detection unit 262, an image processing unit (not shown) performs image processing, and an image of the sample SA obtained by the image processing by the image processing unit is displayed on a display device (not shown).

[0086] Next, the optical device 210 of the second embodiment is described. The optical device 210 collects pulse light as excitation light with respect to the sample SA. The pulse time width of the pulse light is, for example, a time width of the femtosecond (fs) order. Fig.15 As shown, the optical device 210 includes a light source unit 20, a first reflector 11, a diffraction grating 12, a collimating lens 13, a second reflector 14, a dichroic mirror 215, galvano mirrors 216, 216, and an objective lens 217. The light source unit 20, the first reflector 11, the diffraction grating 12, the collimating lens 13, and the second reflector 14 are the same as the light source unit 20, the first reflector 11, the diffraction grating 12, the collimating lens 13, and the second reflector 14 of the first embodiment, and the same reference numerals as those of the first embodiment are used, and detailed description is omitted.

[0087] The dichroic mirror 215 transmits the pulse light PL incident on the dichroic mirror 215 toward the galvano mirrors 216, 216. The dichroic mirror 215 also reflects the fluorescence from the sample SA incident on the dichroic mirror 215 via the objective lens 217 and the galvano mirrors 216, 216 toward the detection unit 260 (condenser lens 261).

[0088] The galvano mirrors 216, 216 reflect the pulse light PL transmitted through the dichroic mirror 215 toward the objective lens 217. In addition, the galvano mirrors 216, 216 reflect the fluorescence from the sample SA transmitted through the objective lens 217 toward the dichroic mirror 215. The galvano mirrors 216, 216 can change the direction of travel of the pulse light PL by changing the direction of the reflection surface. By changing the direction of travel of the pulse light PL using the galvano mirrors 216, 216, it is possible to scan in a plane (observation plane) perpendicular to the optical axis of the objective lens 217 in the sample SA. The galvano mirrors 216, 216 are preferably provided at the position of the pupil of the objective lens 217 or at a position conjugate with the pupil.

[0089] The objective lens 217 focuses the pulse light PL reflected by the galvano mirrors 216, 216 on the sample SA. In addition, the diffraction grating 12, the sample SA (observation plane), and the detection unit 262 are conjugate with each other.

[0090] Next, a scanning method using pulse light using the optical device 210 of the microscope device 201 configured as described above will be described. The scanning method of the second embodiment is the same as the scanning method described in the first embodiment, and thus, similarly to the first embodiment, reference will be made to the scanning method described in the second embodiment. Fig.10 First, pulse light is generated similarly to the first embodiment (step ST1 ). Next, pulse light is amplified similarly to the first embodiment (step ST2 ).

[0091] Next, the pulse light is dispersed by the diffraction grating 12 (step ST3). In the second embodiment, the light source unit 20 emits, for example, a pulse light PL in a wavelength range of 1 μm as an excitation light. The pulse light PL emitted from the light source unit 20 is reflected by the first reflector 11 and is incident on the diffraction grating 12. The diffraction grating 12 disperses the pulse light PL reflected by the first reflector 11 by using the diffraction phenomenon. The pulse light PL dispersed in the diffraction grating 12 is transmitted through the collimating lens 13 and becomes parallel, and is incident on the second reflector 14. At this time, the diffraction grating 12 and the collimating lens 13 are used to generate the spatial chirp of the pulse light PL required for time focusing.

[0092] Next, the pulse light is collected by the objective lens 217 (step ST4). The pulse light PL reflected by the second reflector 14 transmits the dichroic mirror 215 and is reflected by the galvano mirrors 216, 216. The pulse light PL reflected by the galvano mirrors 216, 216 is incident on the objective lens 217. The objective lens 217 collects the pulse light PL reflected by the galvano mirrors 216, 216 relative to the sample SA. In addition, the pulse time width of the pulse light PL collected by the objective lens 217 becomes the pulse time width of the pulse light PL when it is incident on the diffraction grating 12 by generating time focusing. This also includes the following situation: the pulse time width of the pulse light PL collected by the objective lens 217 is not only (completely) the same as the pulse time width of the pulse light PL when it is incident on the diffraction grating 12, but also is approximately the same as the pulse time width of the pulse light PL when it is incident on the diffraction grating 12.

[0093] Then, the position where the temporal focus is generated is changed in the optical axis direction of the objective lens 217 to perform scanning (step ST5). At this time, the amplification factors of the first fiber amplifier 25 and the second fiber amplifier 26 are changed by modulating the pump currents of the first pump LD27 and the second pump LD28. Thus, the chirp amount (GDD) of the pulse light PL is changed, and the position where the temporal focus is generated is changed in the optical axis direction of the objective lens 217 to perform scanning in the optical axis direction (z direction). In addition, at this time, the traveling direction of the pulse light PL is changed by using the current mirrors 216, 216, and scanning is performed in the direction perpendicular to the optical axis of the objective lens 217 (XY direction). In addition, in a state where the pulse light PL from the optical device 210 is continuously irradiated to the sample SA, the step (ST1) of generating the pulse light, the step (ST2) of amplifying the pulse light, the step (ST3) of dispersing the pulse light, the step (ST4) of focusing the pulse light, and the step (ST5) of scanning are performed in parallel.

[0094] By irradiating the pulse light PL as the excitation light, the fluorescent material contained in the sample SA is two-photon excited and emits fluorescence with a wavelength shorter than that of the excitation light (pulse light PL). At this time, the pulse time width of the pulse light PL is reduced by the effect of time focusing, and the original pulse time width when incident on the diffraction grating 12 is reproduced in the observation surface of the sample SA (the focal plane of the objective lens 217). Due to the effect of time focusing, the resolution of the microscope device 201 in the optical axis direction (z direction) is improved, so two-photon pumping is generated only in a small area near the focus of the objective lens 217. Therefore, by changing the position (position in the z direction) where time focusing is generated, scanning in the optical axis direction (z direction) can be performed, and by combining with scanning in a direction perpendicular to the optical axis based on the current mirrors 216, 216, a three-dimensional image of the sample SA can be generated.

[0095] In addition, the fluorescence from the sample SA is incident on the objective lens 217. The fluorescence transmitted through the objective lens 217 is reflected by the galvano mirrors 216, 216 and is incident on the dichroic mirror 215. The fluorescence incident on the dichroic mirror 215 is reflected by the dichroic mirror 215 and is incident on the condenser lens 261. The fluorescence transmitted through the condenser lens 261 is condensed to the detection unit 262. In addition, the diffraction grating 12, the sample SA (observation surface), and the detection unit 262 are conjugate with each other. Therefore, by configuring the pulse light PL as the excitation light to be condensed by the objective lens 217 to the observation surface of the sample SA, the fluorescence generated by two-photon pumping and passing through the objective lens 217 can reach the detection unit 262 without leakage.

[0096] According to the second embodiment, the optical device 210 of the microscope device 201 includes: the first fiber amplifier 25 and the second fiber amplifier 26 for amplifying pulsed light; the diffraction grating 12 for dispersing the pulsed light; and the objective lens 217 for focusing the pulsed light dispersed in the diffraction grating 12, and the amplification factors of the first fiber amplifier 25 and the second fiber amplifier 26 can be changed. In addition, the pulse time width of the pulsed light focused by the objective lens 217 becomes the pulse time width of the pulsed light when incident on the diffraction grating 12 by generating temporal focusing. As in the first embodiment, by modulating the pump current of the first pump LD 27 at high speed, the amplification factor of the first fiber amplifier 25 can be changed at high speed, so that the chirp amount (GDD) of the pulsed light can be changed at high speed, and the position (position in the z direction) where temporal focusing is generated can be changed at high speed. In addition, due to the effect of time focusing, even if the focusing radius of the pulse light is set to about 5 to 10 μm, the resolution of the microscope device 201 in the optical axis direction (z direction) becomes high, so the position (position in the z direction) where time focusing occurs is changed at a high speed, thereby enabling high-speed scanning in the optical axis direction (z direction). Therefore, by combining with scanning in a direction perpendicular to the optical axis by the galvano mirrors 216, 216, a three-dimensional image of the sample SA can be generated at a high speed.

[0097] In addition, similarly to the first embodiment, the amplification factor of the second optical fiber amplifier 26 can be adjusted by controlling the pump current of the second pump LD 28, thereby setting the output of the pulse light output from the second optical fiber amplifier 26 to a fixed range. Alternatively, a light quantity regulator such as an acousto-optic modulator (AOM) can be provided on the input side or the output side of the second optical fiber amplifier 26 to control the pulse energy of the pulse light. In this way, the chirp amount (GDD) of the pulse light can be changed, and the variation of the pulse energy of the pulse light can be reduced.

[0098] In addition, similarly to the first embodiment, a compressor 31 may be provided to compress the pulse time width of the pulse light output from the second optical fiber amplifier 26. In this way, pulse light of a Fourier transform-limited pulse can be obtained.

[0099] In the second embodiment described above, similarly to the first embodiment, the oscillator 22 may not be provided, and the first optical fiber amplifier 25 may amplify the pulse light from the pulse light generator provided outside the microscope device 201. In this case, the step (ST1) of generating the pulse light described above can be omitted.

[0100] In the above-mentioned second embodiment, similarly to the first embodiment, a prism or the like may be provided instead of the diffraction grating 12 as a dispersion element for dispersing pulse light.

[0101] In the second embodiment described above, similarly to the first embodiment, the light amount of the input pulse light is controlled by using an acousto-optic modulator (AOM) or the like provided at the input side of the first optical fiber amplifier 25, thereby effectively changing the amplification factor of the first optical fiber amplifier 25 and changing the chirp amount (GDD) of the pulse light. Alternatively, the light amount of the pulse light may be controlled by using an acousto-optic modulator (AOM) or the like provided at the input side or the output side of the second optical fiber amplifier 26, thereby effectively changing the amplification factor of the second optical fiber amplifier 26 and maintaining the output of the second optical fiber amplifier 26 within a fixed range.

[0102] In the above-mentioned second embodiment, the light source unit 20 may include only one amplifier instead of the two-stage amplifier (the first optical fiber amplifier 25 and the second optical fiber amplifier 26 ) as in the first embodiment.

[0103] In the above-mentioned second embodiment, the compressor 31 may be configured using a prism pair instead of a diffraction grating pair (grating pair) as in the first embodiment.

[0104] In the second embodiment described above, the compressor 31 is provided in the light source unit 20 as in the first embodiment, but the present invention is not limited thereto and the compressor may not be provided in the light source unit. For example, the optical device of the microscope device 201 may be configured similarly to the optical device 110 of the modification of the first embodiment.

[0105] In the above-mentioned second embodiment, a two-photon excitation fluorescence microscope (multi-photon excitation fluorescence microscope) is illustrated and described as an example of the microscope device 201, but it is not limited to this. For example, it can be a second harmonic generation (SHG) microscope or a third harmonic generation (THG) microscope.

[0106] Description of Reference Numerals

[0107] 1. Photoprocessing Device (First Embodiment)

[0108] 10. Optical Device

[0109] 12 Diffraction grating 13 Collimating lens

[0110] 17 Objective lens

[0111] 20 light source units

[0112] 22 Oscillator (pulse light generator)

[0113] 25 1st optical fiber amplifier 26 2nd optical fiber amplifier

[0114] 27 1st pump LD 28 2nd pump LD

[0115] 31 Compressor

[0116] 110 Optical device (modification)

[0117] 111 1st diffraction grating 112 2nd diffraction grating

[0118] 117 objective lens

[0119] 120 light source units

[0120] 122 Oscillator (pulse light generator)

[0121] 125 Fiber Amplifier

[0122] 127 Pump LD

[0123] 201 Microscope Device (Second Embodiment)

[0124] 210 Optical device 217 Objective lens

[0125] PL pulse light.

Claims

1. An optical device comprising: An amplifier for amplifying pulsed light; a dispersion element for dispersing the pulse light output from the amplifier; and an objective lens for focusing the pulse light dispersed in the dispersion element, The optical device is capable of changing the amplification factor of the amplifier.

2. The optical device according to claim 1, in, A collimator lens is provided, which makes the pulse light dispersed in the dispersion element collimate. The objective lens collects the pulse light transmitted through the collimating lens. The pulse time width of the pulse light focused by the objective lens becomes the pulse time width of the pulse light when incident on the dispersion element by causing temporal focusing.

3. The optical device according to claim 1 or 2, in, having a second amplifier for amplifying the pulse light output from the amplifier, The dispersion element disperses the pulse light output from the second amplifier, The optical device is capable of changing the amplification factor of the second amplifier.

4. The optical device according to claim 3, in, By changing the amplification factor of the amplifier, the position where time focusing occurs is changed in the direction of the optical axis of the objective lens. By changing the amplification factor of the second amplifier, the output of the pulse light output from the second amplifier is set within a fixed range.

5. The optical device according to claim 3 or 4, in, A compressor is provided for compressing the pulse time width of the pulse light output from the second amplifier.

6. A light processing device comprising an optical device for scanning a pulse light irradiated on a workpiece, The optical device is the optical device according to any one of claims 1 to 5.

7. A microscope device having an optical device for scanning pulsed light irradiated on a sample, The optical device is the optical device according to any one of claims 1 to 5.

8. A scanning method, wherein include: Using an amplifier to amplify the pulsed light; Using a dispersive element to disperse the pulsed light output from the amplifier; as well as The pulse light dispersed in the dispersion element is focused by using an objective lens, By changing the gain of the amplifier, the position where the pulse light focused by the objective lens is focused at the time of generation is changed in the optical axis direction of the objective lens to perform scanning.

Images