High-frequency imaging device

Abstract

To provide a high frequency imaging device capable of imaging distribution of an internal excitation state of a high frequency device at a given excitation frequency with high speed and high sensitivity.SOLUTION: An apparatus 10 for visualizing distribution of an electrical internal excitation state of a device into which a high frequency signal is inputted comprises: a first signal source 12 that injects a first signal to the device via a signal line 17 to excite a high frequency physical phenomenon; a pulse laser 14 outputting repeated pulse light; a second signal source 13 generating a second signal; an electro-optical modulation part 16 performing amplitude modulation on pulse light according to the second signal inputted from the second signal source; and an imaging part 19 that receives reflected light obtained by the device being irradiated with the amplitude-modulated pulse light. The first signal, output timing of pulse light of the pulse laser and the second signal are synchronized with each other, and when the frequency of the first signal is deviated from an integral multiple of repeated frequency of the pulse light, the frequency of the second signal is set based on the deviated frequency.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to an evaluation technique for high-frequency devices, and more specifically, to a technique for visualizing the distribution of the electrical internal excitation states of high-frequency devices. [Background technology]

[0002] In recent years, communication speeds have improved dramatically, leading to the practical application of the fifth-generation mobile communication system (5G system), and further development of the sixth-generation mobile communication system (6G system) as "Beyond 5G." 5G systems utilize radio waves in the 3-6 GHz band and the 24-28 GHz band (quasi-millimeter wave). 6G systems use frequency bands above 100 GHz. Technologies for evaluating the behavior of high-frequency devices used at such high frequencies, such as amplifiers, antennas, surface wave filters, mixers, and radio wave absorbers, are needed.

[0003] In the evaluation of high-frequency devices, input / output characteristics are typically measured using a vector network analyzer (VNA). However, this alone does not provide insight into the internal behavior of the device. A high-frequency imaging device has been developed that excites a high-frequency device with a high-frequency signal and captures the spatial distribution of its internal excited state using ultrashort pulse light phase-locked to the excitation signal. This device allows for the evaluation of the spatial distribution imaging of electrically excited physical quantities that interact with light, such as electric dipole moments, magnetic moments, and high-frequency electric fields (see, for example, Non-Patent Documents 1-3).

[0004] In conventional high-frequency imaging devices using ultrashort pulse light, a mode-locked laser generates ultrashort pulse light at a constant period. The high-frequency device to be measured is excited by a high-frequency electrical signal with a frequency phase-locked to the ultrashort pulse light. The high-frequency imaging device irradiates the high-frequency device with ultrashort pulse light at a specific phase, and performs spatial distribution imaging by stroboscopically imaging the excited state of the high-frequency device at that phase. [Prior art documents] [Non-Patent Literature]

[0005] [Non-Patent Literature 1] K. Yang et al., IEEE Trans. Microwave Theory and Tech., 2000, vol. 48, pp. 288-293. [Non-Patent Literature 2] C. Hubert et al., Review of Scientific Instruments 1999, vol. 70, 3684-3687. [Non-Patent Literature 3] S. Tamaru et al., Journal of Applied Physics 2002, vol. 91, 8034-8036. [Summary of the Invention] [Problem to be Solved by the Invention]

[0006] Two methods are used for spatial distribution imaging of internal excitation states of high-frequency devices. In the first method, a high-frequency device is irradiated with a light spot obtained by focusing an ultrashort pulsed light at a single point, and reflected light therefrom is detected by a photodiode. The spatial distribution of the internal excitation state is obtained by scanning the light spot over the high-frequency device and repeating this measurement. In the second method, the spatial distribution of the internal excitation state is obtained by causing ultrashort pulsed light to be incident as a plane wave on the entire surface of a high-frequency device, and photographing the entire surface at once with a camera of a two-dimensional image sensor to capture the reflected light.

[0007] In these methods, a mode-locked laser is used as a light source for ultrashort pulsed light, and the repetition frequency f of the ultrashort pulsed light p is normally on the order of several tens of MHz. The excitation frequency f of the high-frequency device e if the excitation frequency f is an integer multiple of the repetition frequency f of the ultrashort pulsed light p , the ultrashort pulsed light irradiates the high-frequency device at a predetermined phase.

[0008] On the other hand, the excitation frequency f e The repetition frequency f of ultrashort pulse light p If the frequency is not an integer multiple of the given value, the incident phase of the ultrashort pulse light shifts. If the frequency of the phase shift is around several tens of MHz, it can be detected using the first method by using a high-speed photodiode for light detection. However, this is undesirable because the time required to scan the light spot with a high-frequency device is excessive.

[0009] The second method allows for simultaneous imaging of reflected light from the entire surface of a high-frequency device. However, the imaging speed is significantly slower than the phase shift frequency. Therefore, when the phase shift frequency is large, around several tens of MHz, the reflected light changes both temporally and spatially, making imaging difficult. Imaging is possible only when the phase shift frequency is small, i.e., when the excitation frequency f e The repetition frequency f of ultrashort pulse light p This restricts the case to neighborhoods that are integer multiples of a given value.

[0010] The object of the present invention is to provide a high-frequency imaging device that can image the distribution of the internal excited states of a high-frequency device at any excitation frequency with high speed and high sensitivity. [Means for solving the problem]

[0011] According to one aspect of the present invention, there is a device for visualizing the distribution of the electrical internal excitation state of a device to be measured into which a high-frequency signal has been injected, comprising: a first signal source that injects a first signal into the device via a signal line to excite a high-frequency physical phenomenon; a pulse laser that outputs repetitive pulsed light; a second signal source that generates a second signal; an electro-optic modulation unit that amplitude modulates the pulsed light in accordance with the second signal input from the second signal source; and an imaging unit that irradiates the device with the amplitude-modulated pulsed light and receives the reflected light, wherein the output timing of the pulsed light of the pulse laser and the second signal are synchronized, and the frequency of the second signal is set based on the deviation frequency when the frequency of the first signal is deviated from an integer multiple of the repetition frequency of the pulsed light.

[0012] According to the above embodiment, the amplitude modulation frequency of the pulsed light is set based on the deviation frequency of the frequency of the first signal that electrically excites the device to be measured from an integer multiple of the repetition frequency of the pulsed light. The reflected pulsed light that interacts with the excited state of the device is incident on the imaging unit at the difference frequency between the deviation frequency and the amplitude modulation frequency, which is lower than the deviation frequency. The lower the difference frequency, the lower the amplitude modulation frequency of the light incident on the imaging unit. This makes it possible to provide a high-frequency imaging device that can image the distribution of the internal excited state of a high-frequency device at any excitation frequency with high speed and high sensitivity. [Brief explanation of the drawing]

[0013] [Figure 1] This is a block diagram showing the schematic configuration of a high-frequency imaging apparatus according to the first embodiment. [Figure 2] This is a schematic overview of the sample stage and device. [Figure 3] This waveform diagram illustrates an example of the operation of a high-frequency imaging device. [Figure 4] This is a block diagram showing the schematic configuration of a high-frequency imaging apparatus according to the second embodiment. [Figure 5]This is a block diagram showing a schematic configuration of a high-frequency imaging apparatus according to the third embodiment. [Modes for carrying out the invention]

[0014] The embodiments will be described below based on the drawings. Elements common to multiple drawings will be denoted by the same reference numerals, and detailed descriptions of those elements will not be repeated.

[0015] [First Embodiment] Figure 1 is a schematic diagram of the high-frequency imaging apparatus according to the first embodiment. In Figure 1, solid lines connecting the components indicate electrical wiring, and dotted lines indicate the path of pulsed light. Figure 2 is a schematic overview of the sample stage and device. Referring to Figures 1 and 2, the high-frequency imaging apparatus 10 includes a reference clock source 11, a first high-frequency signal source 12, a second high-frequency signal source 13, a pulsed laser 14, a frequency control unit 15, an electro-optic modulator 16, a signal line 17 for injecting a high-frequency signal to electrically excite the device DUT to be measured, and a camera 19. The high-frequency imaging apparatus 10 can capture the distribution of the electrical internal excitation state of the device DUT with the camera 19 by injecting an electrical high-frequency signal into the signal line 17 to excite the device DUT to be measured and then irradiating it with pulsed light amplitude-modulated by the electro-optic modulator 16.

[0016] The reference clock source 11 generates a clock signal and supplies it to the first high-frequency signal source 12, the second high-frequency signal source 13, and the pulsed laser 14. The reference clock source 11 may be, for example, a reference clock signal output unit built into the measuring instrument, or a commercially available reference frequency signal source (for example, Meridian II Precision TimeBase from EndRun Technologies). The reference clock source 11 is not particularly limited as long as it exhibits sufficient stability and provides a signal that can synchronize the first high-frequency signal source 12, the second high-frequency signal source 13, and the pulsed laser 14.

[0017] The first high-frequency signal source 12 generates a first high-frequency electrical signal in phase-synchronized with the clock signal supplied from the reference clock source 11. The first high-frequency signal has no lower frequency limit, with an upper limit of, for example, 2 THz, and is a signal in the microwave band (3 GHz to 30 GHz) or millimeter-wave band (30 GHz to 300 GHz). The first high-frequency signal source 12 is not particularly limited as long as it is a signal generator that generates signals in phase synchronization, but for example, a Keysight Model PSG can be used.

[0018] The signal line 17 is connected to the output of the first high-frequency signal of the first high-frequency signal source 12, and the first high-frequency signal is injected into the device DUT to be measured. The device DUT is a high-frequency device used at high frequencies, such as an amplifier, antenna, surface wave filter, mixer, etc. The first high-frequency signal is injected according to the excitation state of the device DUT that you want to image. For example, in the case of an amplifier, antenna, surface wave filter, mixer, etc., since it has a high-frequency transmission path inside, the signal line 17 should be connected to its signal input.

[0019] Furthermore, if the device DUT is made of a material such as a radio wave absorber, soft magnetic material, or dielectric material and it is desired to image the high-frequency excited state, the sample stage 18 shown in Figure 2 may be used. The sample stage 18 includes a signal line 17a and a ground line 17b. The sample stage 18 has a substrate 20 and a glass substrate 21 on top of it. The signal line 17a is provided on the surface of the substrate 20, and in the case of a coplanar waveguide, ground lines 17b are provided on both sides. The substrate 20 is made of a dielectric material, such as ceramic or resin, and the signal line 17a and ground line 17b are made of a conductive material, such as copper.

[0020] The second high-frequency signal source 13 is phase-locked to the clock signal supplied from the reference clock source 11, and generates a second high-frequency signal which is an electrical signal. The frequency of the second high-frequency signal is set to be lower than half the repetition frequency of the light emission output of the pulse laser 14. For example, when the repetition frequency of the pulse laser 14 is 80 MHz, the frequency is set to 0 to 40 MHz. The output unit of the second high-frequency signal source 13 is connected to the modulation signal input unit of the electro-optic modulator 16, and supplies the second high-frequency signal. The second high-frequency signal source 13 is not particularly limited as long as it is a signal generator that generates a signal through phase synchronization, and for example, Model 33611A manufactured by Keysight Corporation can be used.

[0021] The pulse laser 14 is a mode-locked laser, and can generate ultrashort pulsed light having a pulse width of picoseconds or femtoseconds. For the pulse laser 14, for example, a titanium sapphire laser or an argon laser can be used. For the titanium sapphire laser, the emission wavelength can be set in a range from 660 nm to 1100 nm, and the repetition frequency f of the light emission output p is 70 MHz to 150 MHz. The pulse laser 14 synchronizes its output timing with the clock signal supplied from the reference clock source 11, and supplies the pulsed light to the electro-optic modulator 16.

[0022] The frequency control unit 15 is connected to the first high-frequency signal source 12, the second high-frequency signal source 13 and the pulse laser 14 so that frequency control information can be transmitted (illustration of connection lines is omitted). The frequency control unit 15 controls the frequency f of the first high-frequency signal from the first high-frequency signal source 12 e and the repetition frequency f of the pulse laser 14 p to set the frequency f of the second high-frequency signal from the second high-frequency signal source 13 m . Specifically, the frequency control unit 15 controls the frequency f of the first high-frequency signal e to be the repetition frequency f of the pulse laser 14 p when it deviates from an integer multiple of the repetition frequency f, the frequency f of the second high-frequency signal is adjusted based on the deviation frequency m is set. Using the congruence expression (mod), the deviation frequency is f e (mod fp ) is expressed as f e to f p This refers to the remainder when divided by, and the frequency control unit 15 performs this calculation. The frequency control unit 15 further calculates f e (mod f p )-f p The calculation is performed to find the absolute value of / 2. The frequency control unit 15 performs the operation to find the absolute value of f e (mod f p ) and f e (mod f p )-f p The absolute value of / 2 (i.e., |f e (mod f p )-f p The frequency f of the second high-frequency signal of the second high-frequency signal source 13 is compared with ( / 2|) and the smaller one is used. m The frequency control unit 15 sets the frequency f to the second high-frequency signal source 13. m The second high-frequency signal source 13 transmits this as frequency control information, and the received second high-frequency signal source 13 has a frequency f m A second high-frequency signal is generated.

[0023] The frequency control unit 15 controls the frequency f of the first high-frequency signal of the first high-frequency signal source 12. e To configure this setting, the first high-frequency signal source 12 is set to a frequency f e The first high-frequency signal source 12 transmits this as frequency control information, and the received first high-frequency signal source 12 has a frequency f e The frequency control unit 15 may be configured to generate a first high-frequency signal when the pulse laser 14 has a repetition frequency f p If it is variable, you may set it accordingly. The frequency control unit 15 can use a personal computer (PC), and the frequency control unit 15 may be included in the PC 26 described later.

[0024] The electro-optic modulator 16 has the function of amplitude modulation of pulsed light. The electro-optic modulator 16 is appropriately selected according to the wavelength of the pulsed light, the repetition frequency, the beam size of the pulsed light, and the amplitude modulation frequency. For example, the electro-optic modulator 16 can be one in which a Pockels cell and a polarizer are arranged in series in that order (e.g., the EO-AM-NR-C4 amplitude modulator from ThorLabs). The Pockels cell modulates the polarization direction, i.e., the polarization plane, of the pulsed light according to the applied voltage. The polarizer converts the polarization-modulated pulsed light into a linearly polarized state to produce amplitude-modulated pulsed light. The electro-optic modulator 16 receives pulsed light from the pulsed laser 14 as input to its optical input. The electro-optic modulator 16 receives a second high-frequency signal from the second high-frequency signal source 13 as input to its modulation signal input. The electro-optic modulator 16 amplitude modulates the pulsed light according to the second high-frequency signal. For example, if the repetition frequency of the pulsed light is 80 MHz and the frequency of the second high-frequency signal is 20 MHz, the electro-optic modulator 16 outputs pulsed light with a repetition frequency of 80 MHz, the amplitude of which changes sinusoidally at a frequency of 20 MHz. The electro-optic modulator 16 may also be placed between the polarizing beam splitter 24 and the camera 19, within the range of the beam diameter of the input pulsed light.

[0025] The camera 19 has a two-dimensional image sensor, and for example, a CMOS (complementary metal-oxide-semiconductor) image sensor can be used. The camera 19 only needs to be able to measure still images, and it may also be able to measure video (for example, with a frame rate of about 100 fps).

[0026] The high-frequency imaging apparatus 10 may irradiate the device DUT with pulsed light amplitude-modulated by the electro-optic modulator 16 via a collimator lens 21, a half-mirror 22, and an objective lens 23. The collimator lens 21 and the objective lens 23 adjust the beam diameter of the pulsed light to irradiate the entire surface of a desired area of ​​the device DUT.

[0027] The high-frequency imaging device 10 passes pulsed light reflected from the surface of the device DUT and transmitted through the objective lens 23 and half mirror 22 through a polarizing beam splitter 24 to convert the polarization plane change into an amplitude change, and forms an image on the two-dimensional image sensor of the camera 19 using an imaging lens 25. The camera 19 transmits the acquired image data of the internal excitation state of the device DUT to the PC (personal computer) 26. The PC 26 stores the image data in memory, hard disk drive, etc. (not shown) and outputs the image data to a monitor, printer, etc. (not shown).

[0028] Figure 3 is a waveform diagram illustrating an example of the operation of a high-frequency imaging device. In Figure 3, the dashed lines in (a), (b), and (d) and the vertical axis in (e) represent voltage, and the solid lines in (c) and (d) represent light intensity (amplitude). The horizontal axis represents time. Referring to Figure 3 in conjunction with Figures 1 and 2, the reference clock source 11 of the high-frequency imaging device 10 generates the clock signal shown in Figure 3(a) and supplies it to the first high-frequency signal source 12, the second high-frequency signal source 13, and the pulsed laser 14. As an example, the frequency of the clock signal is set to 80 MHz.

[0029] The first high-frequency signal source 12 is phase-synchronized with the clock signal and operates at the frequency f shown in Figure 3(b). e An electrical first high-frequency signal is generated and supplied to the signal line of the sample stage 18 via the signal line 17. For example, the first high-frequency signal has a frequency f e This was set to a 1.1 GHz sine wave. As a result, the first high-frequency signal is sent to the device DUT as an excitation signal from the signal line at frequency f e A 1.1 GHz high-frequency electric or magnetic field is applied, causing the device DUT to exhibit an electrically excited internal state. The voltage of the first high-frequency signal can be selected as appropriate. In Figure 3(b), the first high-frequency signal is shown intermittently over time for illustrative purposes.

[0030] The pulsed laser 14 synchronizes its output timing with the clock signal, and its repetition frequency f p The pulsed light shown in Figure 3(c) is output to the electro-optic modulator 16. For example, the repetition frequency f of the pulsed lightp The frequency was set to 80 MHz. For illustrative purposes, the pulse width of the pulsed light is shown expanded, but the actual pulse width is, for example, around 100 fs (100 femtoseconds).

[0031] The second high-frequency signal source 13 is phase-synchronized with the clock signal to the frequency f shown in Figure 3(d). m A second electrical high-frequency signal, indicated by the dashed line, is generated and supplied to the modulation signal input section of the electro-optic modulator 16. The frequency f of the second high-frequency signal m The frequency is calculated and set by the frequency control unit 15. e (mod f p ) and f e (mod f p )-f p It is set to the smaller of the absolute values ​​of / 2. Here, f e =1.1GHz, f p =80MHz, f e (mod f p ) = 60MHz, |f e (mod f p )-f p Since / 2|=20MHz, f m The frequency is set to 20 MHz. The electro-optic modulator 16 performs amplitude modulation of the pulsed light in response to the second high-frequency signal. The amplitude-modulated pulsed light is shown as a dashed line in Figure 3(d). The peak value of the amplitude-modulated pulsed light is the frequency f m At 20MHz, the frequency changes between A, A / 2, 0, and A / 2 during one cycle.

[0032] The amplitude-modulated pulsed light output from the electro-optic modulator 16 is irradiated onto a desired area of ​​the device DUT surface via the collimator lens 21, half mirror 22, and objective lens 23. The device DUT is irradiated with the frequency f of the first high-frequency signal. eThe internal excited state changes. By irradiating the device with amplitude-modulated pulsed light, the internal excited state of the device DUT is sampled at a specific phase and reflected in the pulsed light reflected by the device DUT. The reflected pulsed light is a superposition of the amplitude-modulated pulsed light and the internal excited state of the device DUT. The reflected pulsed light reflects only the internal excited state of the device DUT at the positive peak of the first high-frequency signal (shown as white circles in the 1st and 55th cycles in Figure 3(e)). The internal excited state of the device DUT at the negative peak of the first high-frequency signal (shown as a white square in the 27th cycle in Figure 3(e)) is not reflected because the pulse height of the pulsed light is zero and therefore the reflected light is zero. Also, when the first high-frequency signal is zero (shown as a white triangle in the 14th and 41st cycles in Figure 3(e)), the internal excited state is also zero and is not reflected in the reflected pulsed light. In this way, the reflected pulsed light reflects the internal excited state of the device DUT at the positive peak of the first high-frequency signal, at the amplitude modulation frequency f m The same frequency is used for repetition, and the same frequency is used for the camera 19. Since the camera 19 is incident with an image of the internal excitation state of the device DUT that is in the same phase as the first high-frequency signal, it can capture images even with a camera 19 at a low frame rate.

[0033] The high-frequency imaging apparatus 10 of this embodiment can electrically excite the device DUT to be measured, and the camera 19 can capture and image the distribution of all high-frequency physical phenomena that directly interact with the irradiated pulsed light. The high-frequency imaging apparatus 10 can capture the pulsed light reflected from a desired range onto which the pulsed light is irradiated, all at once with the camera 19. As a result, the distribution of the internal excitation state of the high-frequency device can be imaged at a faster speed than the first method described above, which involves irradiating the high-frequency device with a light spot and scanning it.

[0034] The high-frequency imaging apparatus 10 of this embodiment uses a first high-frequency signal with a frequency f that electrically excites the high-frequency device DUT. e The repetition frequency f of pulsed light pBased on the frequency deviation from an integer multiple of the frequency, the frequency f of the second high-frequency signal that amplitude modulates the pulsed light is determined. m The frequency of the second high-frequency signal f is set, and the reflected pulsed light interacting with the excited state of the device shifts between the frequency and the frequency of the second high-frequency signal f. m Since the light incident on camera 19 is at a difference frequency, it becomes lower than the shift frequency. The smaller the difference frequency, the smaller the frequency of amplitude modulation of the light incident on camera 19. As a result, while the conventional technique (the second method described above) was limited to cases where the excitation frequency was near an integer multiple of the repetition frequency of the ultrashort pulse light, in this embodiment, it is possible to image the distribution of the internal excitation state of the high-frequency device DUT at any first high-frequency signal (excitation frequency).

[0035] The high-frequency imaging device 10 can image high-frequency physical phenomena such as the excited state of high-frequency magnetization of a magnetized film (soft magnetic film), which is a phenomenon in which the polarization plane of reflected pulsed light changes when pulsed light is irradiated onto the high-frequency magnetization due to the magnetic Kerr effect. The high-frequency imaging device 10 can capture all of the pulsed light reflected from a desired range onto which pulsed light is irradiated, and whose polarization plane has changed, using the camera 19.

[0036] Another example of a high-frequency physical phenomenon that can be imaged by the high-frequency imaging device 10 is the excitation state of a device DUT by elastic waves. The surface of the device DUT vibrates due to elastic waves, and pulsed light irradiated over a desired range interacts directly with the surface of the device DUT. The reflected pulsed light, whose intensity and phase distribution have changed within the desired range, can be captured all at once by the camera 19.

[0037] [Second Embodiment] Figure 4 is a schematic diagram of the high-frequency imaging apparatus according to the second embodiment. In Figure 4, solid lines connecting the components indicate electrical wiring, and dotted lines indicate the path of pulsed light.

[0038] Referring to Figure 4, the high-frequency imaging apparatus 40 according to the second embodiment has the same configuration as the high-frequency imaging apparatus 10 according to the first embodiment shown in Figure 1, except that an EO (Electro-Optic) sensor 41 using the electro-optic effect is placed on the device DUT. The EO sensor 41 can be, for example, a Pockels crystal thin film.

[0039] In this embodiment, the high-frequency imaging apparatus 40 can observe the high-frequency electric field of the device DUT by changing the birefringence of the EO sensor 41 due to the high-frequency electric field emitted when the device DUT is electrically excited, and by capturing the polarization state of the pulsed light that is reflected by pulsed light irradiated to a desired area of ​​the device DUT and transmitted through the EO sensor 41 with the camera 19.

[0040] [Third Embodiment] Figure 5 is a schematic diagram of the high-frequency imaging apparatus according to the third embodiment. In Figure 5, solid lines connecting the components indicate electrical wiring, and dotted lines indicate the path of pulsed light.

[0041] Referring to Figure 5, the high-frequency imaging apparatus 50 according to the third embodiment has the same configuration as the high-frequency imaging apparatus 10 according to the first embodiment shown in Figure 1, except that the electro-optic modulator 51 is placed between the polarizing beam splitter 24 and the imaging lens 25. The electro-optic modulator 51 modulates the amplitude of the incident pulsed light in response to the second high-frequency signal. The device DUT controls the frequency f of the first high-frequency signal. e The internal excited state changes. In this configuration, first, the amplitude is not modulated, and the repetition frequency f p As shown in Figure 3(e), the pulsed light samples the internal excited state of the device DUT at a specific phase and reflects this sample in the pulsed light reflected by the device DUT. The reflected pulsed light is then converted from polarization change to amplitude change by the polarization beam splitter 24 and further incident on the electro-optic modulator 51, where it is amplitude-modulated according to the second high-frequency signal. This is then imaged by the camera 19 to acquire image data of the internal excited state of the device DUT.

[0042] The electro-optic modulator 51 may also be placed between the imaging lens 25 and the camera 19.

[0043] In this embodiment, the high-frequency imaging apparatus 50 first modulates the pulsed light irradiated onto the device DUT by the DUT and the polarizing beam splitter 24, and then performs amplitude modulation according to the second high-frequency signal by the electro-optic modulator 51, thereby changing the frequency f of the first high-frequency signal. e The internal excitation state of the device DUT, which changes accordingly, is sampled, and the same effect as in the first embodiment is obtained. In other words, in this embodiment, the order of modulation by the pulsed light DUT and modulation by the electro-optic modulator 51 is reversed compared to the first embodiment.

[0044] Although preferred embodiments of the present invention have been described in detail above, the present invention is not limited to these specific embodiments, and various modifications and changes are possible within the scope of the present invention as described in the claims. [Explanation of Symbols]

[0045] 10,40,50 High-frequency imaging device 11. Reference clock source 12 First High-Frequency Signal Source 13. Second high-frequency signal source 14 pulsed lasers 15 Frequency Control Unit 16.51 Electro-optic modulator 17 Signal Line 18 Sample Stages 19 Cameras 21 Collimator lens 22 Half Mirror 23 Objective lens 24 Polarizing Beam Splitter 41 EO Sensor DUT Device

Claims

1. A device for visualizing the distribution of electrical internal excitation states of a device under measurement into which a high-frequency signal has been injected, A first signal source that injects a first signal into the device via a signal line to excite a high-frequency physical phenomenon, A pulsed laser that outputs repeatedly pulsed light, A second signal source that generates a second signal, An imaging unit that irradiates the device with the pulsed light from the pulsed laser and receives the pulsed light reflected from the device, An electro-optic modulation unit that performs amplitude modulation on the pulsed light before it is irradiated onto the device, or the pulsed light reflected from the device, in accordance with the second signal input from the second signal source, The apparatus comprises a frequency control unit that synchronizes the output timing of the pulsed light of the pulsed laser with the second signal, and sets the frequency of the second signal based on the deviation frequency when the frequency of the first signal deviates from an integer multiple of the repetition frequency of the pulsed light.

2. Let the frequency of said first signal be f 1 and the repetition frequency of said pulsed light be f p , then said deviation frequency is expressed as f 1 (mod f p ), and the frequency f of said second signal 2 is set to the smaller one between f 1 (mod f p ) and the absolute value of f 1 (mod f p ) - f p / 2, the apparatus according to claim 1.

3. The apparatus according to claim 1 or 2, wherein the electrical internal excitation state is a high-frequency physical phenomenon that oscillates at the frequency of the first signal and interacts with light.

4. The apparatus according to claim 3, wherein the aforementioned high-frequency physical phenomenon is a phenomenon caused by high-frequency magnetization or elastic waves.

5. The apparatus according to claim 1 or 2, further comprising an electro-optic sensor disposed on the device and acting on the pulsed light reflected from the device in response to electromagnetic waves emitted by the device.

6. The apparatus according to claim 5, wherein the electrical internal excitation state oscillates at the frequency of the first signal, and the high-frequency physical phenomenon is a phenomenon caused by a high-frequency electric field.

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