JP2008020304A - High-speed imaging apparatus for electromagnetic-field - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To speedily acquire electromagnetic near-field distributions radiated from a specimen. <P>SOLUTION: When an illumination device 11 irradiates a probe 12 with light amplitude-modulated at a frequency f<SB>LO</SB>, an electromagnetic field of a frequency f<SB>RF</SB>radiated from a specimen α locally changes birefringence characteristics of the probe 12 to generate a state of local polarization in the illumination light. The sate of local polarization in detecting light containing a difference frequency component Δf(¾f<SB>LO</SB>-f<SB>RF</SB>¾) between a modulation frequency f<SB>LO</SB>of the illumination light and the frequency f<SB>RF</SB>of the electromagnetic field radiated from the specimen α is converted into local intensity of light and imaged by an image sensor 13c of an imaging apparatus 13. An image processing device 14 performs arithmetic processing on pixel signals extracted by the image sensor 13c for every pixel to generate a two-dimensional image of an electromagnetic near-field distribution radiated from the specimen α and display it on an image display device 15. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electromagnetic field high-speed imaging apparatus that acquires electric field / magnetic field distribution information radiated from a specimen at high speed and visualizes it as a two-dimensional image.

  In recent years, along with the advancement, miniaturization, and speeding up of electronic devices, the density of printed circuit boards has increased, and at the same time, the speed of electric signals and the increase in bandwidth have become significant. For example, integrated circuits and portable devices that operate at a very high frequency exceeding 1 GHz have been developed. However, as a problem of circuit technology that drives at such a high frequency, the difficulty in designing due to electromagnetic interference between circuits is remarkable. It has become. By grasping the distribution of the electromagnetic field generated when driving such a high-frequency circuit, it is possible to efficiently perform a redesign or the like that avoids the problem, and various proximity electromagnetic field measuring apparatuses have been proposed.

  As such a near electromagnetic field measuring apparatus, there is one that takes out a detection current generated in a probe with a cable by placing a measuring electromagnetic field probe in the near electromagnetic field. However, since the detection current flowing through the probe close to the sample and the cable connected to the probe affects the near electromagnetic field of the sample, it is not suitable for performing highly accurate measurement.

  Therefore, a magneto-optic probe is attached to the tip of the optical fiber to make a magneto-optic probe, and light is propagated by the optical fiber to the magneto-optic crystal at the tip of the magneto-optic probe placed in the electromagnetic field from the specimen. An optical fiber end magneto-optic probe system that measures an electromagnetic field at the tip position of the magneto-optic probe by analyzing reflected light that has been irradiated and modulated on the magneto-optic crystal that is received by a spectrum analyzer has been proposed (for example, (Refer nonpatent literature 1).

Masahiro Tsuchiya, Atsushi Yamazaki, Shinichi Wakana, Hayato Kishi, “Microwave Microwave Magnetic Field Distribution Measurement Using Optical Fiber Edge Magnetooptic (FEMO) Probe”, Japan Society of Applied Magnetics, Vol. 26, no. 3, 2002, p. 128-134

  However, in the invention described in Patent Document 1, since the distribution of the near electromagnetic field radiated from the specimen cannot be measured collectively, the measurement point of the probe is sequentially shifted by controlling the measurement system or the sample position, The electromagnetic field radiation surface of the specimen had to be scanned to measure the electromagnetic field distribution. Therefore, in order to obtain a distribution image, a very long measurement time such as several tens of seconds to several hours is required.

  Therefore, an object of the present invention is to provide an electromagnetic field high-speed imaging device that can acquire the distribution of the near electromagnetic field radiated from the specimen at high speed.

In order to solve the above-mentioned problem, the invention according to claim 1 includes a lighting device capable of outputting light modulated in amplitude by the frequency f _LO and an electric field or magnetic field of the frequency f _RF emitted from the specimen to be measured. By locally changing the refraction characteristics, a local polarization state is generated in the light emitted from the illumination device, and the illumination light from the illumination device is further modulated by an electromagnetic field in the vicinity of the frequency f _RF to mix the frequencies. Thus, it is possible to generate detection light including a difference frequency component Δf (| f _LO −f _RF |) between the modulation frequency f _{LO of the} light emitted from the illumination device and the frequency f _RF of the electric field or magnetic field radiated from the specimen. A probe including an electro-optic element or a magneto-optic element, and photoelectric conversion for converting a local polarization state in detection light from the probe into a local intensity of light and forming an image on an imaging surface of an image sensor having a plurality of pixels Imaging device And an image processing device that analyzes the distribution information of the near electromagnetic field radiated from the specimen using the difference frequency component Δf included in the pixel signal extracted for each pixel from the image sensor of the imaging device and generates a two-dimensional image And.

  The invention according to claim 2 is the electromagnetic field high-speed imaging device according to claim 1, wherein a laser light source is used as a light source of the illumination device.

In the invention, in the electromagnetic field high speed imaging apparatus according to claim 1 or claim 2, reference frequency ΔfR frequency f _LO and the processing unit of the operating frequency f _RF and illumination device of the sample are the same according to claim 3 It is characterized in that it is supplied from the transmitter signal.

  According to a fourth aspect of the present invention, in the electromagnetic field high-speed imaging device according to any one of the second to third aspects, the image processing device outputs pixel by pixel from an image sensor of the imaging device. Filtering means for passing a band including the difference frequency component Δf from the pixel signal to be processed, and a measuring device for analyzing the filtered output signal output from the filtering means, the measuring device comprising: A reference sine wave and a reference cosine wave are generated based on a reference signal supplied from a modulation signal source, the sine component integration signal obtained by integrating the filtered output signal and the reference sine wave, the filtered output signal and the reference cosine wave, The cosine component integrated signal is calculated and the sum of squares of the sine component integrated signal and the cosine component integrated signal is calculated to calculate the amplitude information and the ratio between the sine component integrated signal and the cosine component integrated signal. To do Phase information, characterized in that so as to obtain respectively.

  Further, the invention according to claim 5 is the electromagnetic high-speed imaging device according to claim 4, wherein the reference sine wave and the reference cosine wave generated by the measurement device are a pseudo reference sine wave and a pseudo wave that are substituted with a rectangular wave. It is a reference cosine wave.

  The invention according to claim 6 is the electromagnetic field high-speed imaging device according to any one of claims 1 to 5, wherein the imaging device connects the real image of the probe to an imaging surface of an image sensor. An imaging optical system for imaging is provided, and a fine light absorber is arranged at the center of the aperture at the infinity focal position on the image sensor side of the imaging optical system.

  According to a seventh aspect of the present invention, in the electromagnetic field high-speed imaging device according to any one of the first to sixth aspects, an illumination light source capable of high light output with respect to the saturation light intensity of the image sensor. And an analyzer and a polarization state control element, and by adjusting the polarization state control element, the polarization state immediately before entering the analyzer is controlled, and among the components included in the detection light transmitted through the analyzer The intensity ratio between the modulated light component generated in the probe of the detection light and the other components can be adjusted.

According to the first aspect of the present invention, the modulation frequency f _{LO of the} light emitted from the illuminating device and the frequency of the electromagnetic field emitted from the specimen by the probe disposed in the electromagnetic field of the frequency f _RF emitted from the specimen to be measured. the difference frequency component Δf and _{f RF (| f LO -f RF} |) because the detection light can be obtained including, the imaging device a two-dimensional image the behavior of the frequency f _RF is focused on frequency-converted difference frequency component Δf An image processing apparatus can generate electromagnetic field distribution information based on pixel signals captured by the image sensor and extracted for each pixel from the image sensor, and can acquire a distribution image of nearby electromagnetic fields in a very short time. Can do.

Moreover, by appropriately selecting the modulation frequency f _LO , a difference frequency component Δf that is an intermediate frequency lower than the frequency f _{RF of the} electromagnetic field emitted from the specimen can be obtained, and an imaging apparatus and an image that handle the difference frequency component Δf the processing apparatus, the high speed operation can follow the frequency f _RF of the sample is not required, there is an advantage that Kisel the cost reduction of the apparatus configuration.

  According to the electromagnetic field high-speed imaging device according to claim 2, since a laser light source is used as the light source of the illuminating device, low noise electromagnetic field distribution by laser light having excellent monochromaticity, directivity, and polarization property. Detection is possible.

The invention according to claim 3, since the reference frequency ΔfR frequency f _LO and the processing unit of the operating frequency f _RF and illumination device of the sample was then supplied from the same oscillator signal is the relative fluctuations of the frequency Phase noise can be eliminated.

  According to the electromagnetic field high-speed imaging device according to claim 4, the image processing device includes a filtering unit that passes the difference frequency component Δf from the pixel signal output for each pixel from the image sensor of the imaging device; A measurement device for analyzing the filtered output signal output from the filtering means, the measuring device based on a reference signal ΔfR supplied from a modulation signal source of the illumination device, and a reference sine wave and a reference cosine wave And calculating a sine component integrated signal obtained by integrating the filtered output signal and the reference sine wave, and a cosine component integrated signal obtained by integrating the filtered output signal and the reference cosine wave, respectively. The amplitude information can be obtained by calculating the sum of squares with the component integration signal, and the phase information can be obtained by calculating the ratio between the sine component integration signal and the cosine component integration signal.

  According to the electromagnetic field high-speed imaging device according to claim 5, since the reference sine wave and the reference cosine wave generated by the measurement device are a pseudo reference sine wave and a pseudo reference cosine wave substituted by a rectangular wave, Calculation processing of the component integration signal and the cosine component integration signal can be performed at high speed.

  According to the electromagnetic field high-speed imaging device according to claim 6, the imaging device includes an imaging optical system that forms a real image of the probe on an imaging surface of an image sensor, and the image sensor of the imaging optical system Since the fine light absorber is arranged at the center of the aperture at the infinity focal position on the side, the component parallel to the optical axis of the probe output light can be absorbed, and the noise incident on the imaging surface of the image sensor can be reduced.

  According to the electromagnetic light velocity imaging apparatus according to claim 7, the illumination light source capable of high light output with respect to the saturation light intensity of the image sensor, the analyzer, and the polarization state control element are provided, and the polarization state control is performed. By adjusting the element, the polarization state immediately before entering the analyzer is controlled, and among the components included in the detection light transmitted through the analyzer, the modulated light component generated in the probe of the detection light and other components Since the intensity ratio of the image sensor can be adjusted, the received light intensity of the image sensor is adjusted according to the light intensity of the illumination light source, so that the light intensity of the detection light is kept below the saturation light intensity of the image sensor and the difference frequency component By maximizing the modulation depth at Δf, the measurement sensitivity can be optimized.

  Next, based on the attached drawings, a preferred embodiment of the electromagnetic field high-speed imaging device according to the present invention will be described based on the attached drawings.

FIG. 1 is a schematic configuration diagram of an electromagnetic field high-speed imaging device 10. The electromagnetic field high-speed imaging device 10 has local birefringence characteristics due to an illuminating device 11 that outputs light amplitude-modulated at a frequency f _LO and an electric field or magnetic field of a frequency f _RF radiated from a subject α to be measured. To cause a local polarization state in the light emitted from the illuminating device 11, further mixing the illuminating light from the illuminating device 11 at the frequency f _RF , and modulating the light emitted from the illuminating device 11. In the probe 12 capable of generating detection light including a difference frequency component Δf (| f _LO −f _RF |) between the frequency f _LO and the frequency f _{RF of the} electromagnetic field radiated from the specimen α, and the detection light from the probe 12 An imaging device 13 that converts a local polarization state into a local intensity of light, forms an image on an imaging surface of an image sensor having a plurality of pixels, and performs photoelectric conversion, and a pixel extracted from the image sensor of the imaging device 13 for each pixel Signal An image processing device 14 that generates a two-dimensional image of a near electromagnetic field emitted by the specimen α using the difference frequency component Δf, an image display device 15 that visually displays the two-dimensional image output from the image processing device 14, And a recording device 16 for storing and storing the two-dimensional image generated by the image processing device 14.

The illumination device 11 shown in the present embodiment includes a light source 11a, a modulator 11b for modulating light from the light source 11a, and a modulation signal source 11c for generating a modulation signal having a frequency f _LO for controlling the modulator 11b. And a wavefront matching optical system 11d for matching the wavefront of the output light of the modulator 11b with the light irradiation surface of the probe 12. As the light source 11a, it is desirable to use a laser light source that can output laser light having excellent monochromaticity, directivity, and polarization. Further, if the configuration is such that the laser light itself is directly modulated by controlling the value of the current applied to the laser light source and the like, the modulated light can be obtained from the light source 11a, so that it is not necessary to provide the modulator 11b separately.

The probe 12 that receives illumination light from the wavefront matching optical system 11d of the illuminating device 11 is an electro-optic element or a magnet arranged in the vicinity of α of the sample so as to be affected by the electromagnetic field of the operating frequency f _RF radiated from the sample α. An optical element is used. Since the birefringence characteristic of the electro-optical element or the magneto-optical element included in the probe 12 changes depending on the electric field or magnetic field (near electromagnetic field) emitted by the specimen α, the resultant light beam that is transmitted or reflected depends on the electromagnetic field distribution. Gives the polarization distribution. In addition, the time response of the electro-optic element and the magneto-optic element is extremely high, has a high frequency response compared to the frequency f _RF of the near electromagnetic field emitted by the specimen α, and the distribution of polarization is an electromagnetic field near the specimen α. since the response to the operation frequency f _RF of the field, the illumination light irradiated to the probe 12 from the illumination device 11 outputs after being modulated by the near electromagnetic field of the operating frequency f _RF.

In this way, when the illumination light from the illumination device 11 that is pre-modulated with the frequency f _LO is irradiated to the probe 12, the probe 12 placed under the influence of the electromagnetic field radiated from the specimen α causes the frequency f Further modulation is applied in the vicinity of the _RF field. That is, if the probe 12 is regarded as a mixer in the heterodyne radio receiver, the illumination device 11 is regarded as the same local oscillator, and the near electromagnetic field is regarded as the received signal, the output light of the probe 12 is regarded as the mixer output, that is, an intermediate frequency signal. I can do it.

FIG. 2 shows the relationship of the amplitude modulation frequency superimposed on the detection light from the probe 12 (the horizontal axis is the frequency, and the vertical axis is the modulation frequency component superimposed on the detection light). In addition to the components of the frequencies f _RF and f _LO , the detection light from the probe 12 includes a sum frequency (f _LO + f _RF ) and a difference frequency component Δf (| f _LO −f _RF ) by the product of both frequency components. |) Occurs.

In the electromagnetic field high-speed imaging apparatus 10 shown in the present embodiment, a signal having an operating frequency f _{RF at which} the specimen α operates is generated based on the modulation signal source 11c of the illumination apparatus 11 and supplied to the specimen α. It is as. With this configuration, since the modulation signal source 11c can generate an optical modulation signal having a frequency f _LO that provides an intermediate frequency Δf according to the operating frequency f _RF , 400 kHz to 500 kHz or 10 MHz that can be easily handled by existing equipment. It is also possible to automatically supply the modulator 11b with an optical modulation signal having a frequency f _LO so as to obtain an intermediate frequency Δf of ˜12 MHz. Further, when constituting a supply of the operating frequency f _RF of the operation signal from the specimen α as the modulation signal source 11c is subjected (in FIG. 1, indicated by a broken line), and adding or subtracting a desired intermediate frequency Δf to the operating frequency f _RF An optical modulation signal having the frequency f _LO may be supplied to the modulator 11b.

When the sample α is an IC chip with a high degree of integration, a circuit board having a plurality of ICs, or the like, it may operate at partially different frequencies. For thus operating frequency f _RF is plural analytes alpha, and irradiates illumination light modulated at frequency f _LO according to the operation frequency f _RF of the focused to the probe 12, the electromagnetic from only the target difference frequency component Δf You may make it perform a field distribution analysis.

Moreover, in the electromagnetic field high-speed imaging device 10 of this embodiment, it is also possible to observe simultaneously the behavior of the electromagnetic field that operates at a plurality of frequencies. A plurality of operating frequencies f _RFn analyte α of the plurality corresponding to (n = 1,2, ...) the frequency f _LOn (n = 1,2, ...) by modulating the illumination light at the same time, a plurality of intermediate frequency Delta] f _n ( If n = 1, 2,... are extracted and processed, the behavior of the near electromagnetic field at a plurality of operating frequencies f _RFn can be observed.

  The imaging device 13 that receives the detection light (including the intermediate frequency component Δf) acquired from the probe 12 described above converts the local polarization state in the detection light from the probe 12 into a local intensity of light and extracts it. And an image forming optical system 13b for forming an image of detection light input via the detection optical system 13a, and an image sensor 13c in which an image pickup surface is arranged at an image forming position by the image forming optical system 13b. .

  The image sensor 13c includes a plurality of (practically about 100 × 100 pixels or more) photoelectric detectors on the imaging surface to generate pixel signals, and an electric field or magnetic field on the probe 12 projected onto the imaging surface. The light intensity distribution corresponding to this distribution is photoelectrically converted. The electromagnetic field distribution image projected on the imaging surface of the image sensor 13 c is an image that is frequency-converted to the intermediate difference frequency Δf by the action of the probe 12.

The measuring device 14b processes the pixel signal from the filtering unit 14a using the reference signal having the frequency ΔfR supplied from the modulation signal source 11c, and measures the amplitude and phase difference at the intermediate frequency ΔfR. ΔfR has a value equal to Δf. In general, independent oscillators have frequency fluctuations, which are known as phase noise. In the electromagnetic field high-speed imaging device 10, this phase noise is generated in the vicinity of the intermediate frequency Δf. However, as in the electromagnetic field high-speed imaging apparatus 10 according to the present embodiment, the reference frequency ΔfR frequency f _LO and the image processing apparatus 14 of the operating frequency f _RF and lighting device 11 of the specimen alpha, be supplied from a modulation signal source 11c For example, phase noise, which is a relative fluctuation in frequency, can be eliminated.

  A specific configuration example of the measuring device 14b is shown in FIG. The intermediate frequency Δf component in the pixel signal, which is the output for each pixel, selectively passes through the band-pass filter 141 and is then converted into a digital value by the A / D conversion unit 142, and the sine component integration unit 143a and the cosine component Each is supplied to the integrating means 143b. The sine component integrating means 143a accumulates and adds the product of the reference sine wave (sine wave of frequency ΔfR) generated based on the reference signal supplied from the modulation signal source 11c and the output of the A / D converter 142, and accumulates the sine component. The signal is output, and the cosine component integrating means 143b cumulatively adds the product of the output of the A / D converter 142 to the reference cosine wave (cosine wave of frequency ΔfR) generated based on the reference signal supplied from the modulation signal source 11c. Then, the cosine component integration signal is output.

  If the reference sine wave and the reference cosine wave are 1-bit data, the sine component integrating means 143a and the cosine component integrating means 143b can perform calculations at high speed. A 1-bit sine / cosine wave has an amplitude plus or minus one. If the amplitude data of the sine / cosine wave is a multi-valued bit number, an error, that is, a result with a small noise component can be obtained, but the operation time is consumed and the response is impaired. Any selection can be made according to the desired performance.

  As described above, the sine component integration signal output from the sine component integration unit 143a and the cosine component integration signal output from the cosine component integration unit 143b are supplied to the first calculation unit 144 and the second calculation unit 145, respectively. The The first computing means 144 calculates the sum of squares of the sine component integrated signal and the cosine component integrated signal and generates amplitude information. Similarly, the second calculation means 145 calculates the ratio of the sine component integrated signal and the cosine component integrated signal to generate phase information. In this way, a two-dimensional image showing an electromagnetic field distribution can be obtained by associating the amplitude information and phase information obtained for each pixel with the hue and density.

  The image display device 15 that receives image information from the measurement device 14b displays phase information and amplitude information that change every pixel as a change in hue and density, and changes in the near electromagnetic field radiated from the specimen α. Can be viewed as a moving image. Further, the recording device 16 that records image information from the measuring device 14b as needed may be provided with a reproduction function of the recorded image or operation and displayed on the image display device 15.

  The apparatus configuration diagram of the electromagnetic field high-speed imaging apparatus 20 shown in FIG. 4 shows an example of the detailed structure of the wavefront matching optical system, the detection optical system, and the imaging optical system.

  In FIG. 4, the fiber end 21d, the collimator lens 22a, the quarter wavelength plate 22b, the half wavelength plate 22c, the polarization beam splitter 22d, the quarter wavelength plate 22e, the half wavelength plate 22f, and the dielectric mirror 22g Acts as a wavefront matching optical system. The electro-optic crystal (EO crystal) 23 functions as a probe. The polarization beam splitter 22d, the quarter wavelength plate 22e, and the half wavelength plate 22f function as a detection optical system. The imaging lens 22 functions as an imaging optical system. The image sensor 13 c, the filtering means 14 a of the image processing device 14, and the measuring device 14 b are included in the measurement processing device 24. In this configuration example, the polarization beam splitter 22d, the quarter wavelength plate 22e, and the half wavelength plate 22f are components of the wavefront matching optical system when the light travels to the right and the detection optical system when the light travels to the left in the drawing. It has multiple actions.

  FIG. 5 is a schematic diagram for explaining the operation of the wavefront matching optical system and the detection optical system of the optical system in FIG. Reference numerals 51a, 51b and 51c denote processes in which the polarization planes are sequentially matched by the wavefront matching light. Reference numerals 52c, 52b, and 52a denote processes in which the state of deflection in the wavefront is converted into light intensity by the detection optical system. Reference numerals 53a and 54b show how the output of the polarizing beam splitter 22d is changed by rotating it relative to the electric field on the optical axis. Reference numerals 54a and 54b show examples of temporal changes in the output of the polarizing beam splitter 22d.

In FIG. 4, laser light emitted from a laser light source 21a is introduced into an optical modulator 21b controlled by a transmission frequency f _LO from a high-frequency oscillator 21c through an optical fiber, and illumination light that has been amplitude-modulated is introduced into a fiber end 21d. It is more diffusely radiated and becomes a parallel light beam by the collimator lens 22a. Further, the laser beam passes through a wavefront matching optical system composed of a quarter-wave plate 22b and a half-wave plate 22c, becomes circularly polarized light, travels straight through the polarization beam splitter 22d, and travels through the quarter-wave plate 22e and the half-wave plate. After passing through the plate 22f, the light irradiating surface of the probe 23 in which the optical axis is bent by the reflecting plate 22g and the electro-optic element in which the electro-optic crystal (EO-Crystal) is formed in a plate shape is arranged at a predetermined position by the holding mechanism. Incident vertically. That is, in the present configuration example, the quarter wavelength plate 22b, the half wavelength plate 22c, the polarization beam splitter 22d, the quarter wavelength plate 22e, and the half wavelength plate 22f function as a wavefront matching optical system.

On the other hand, the illumination light irradiated on the light irradiation surface of the probe 23 receives the modulation of the local polarization state by an electric field analyte operating at operating frequency f _RF alpha emitted, detection light containing a intermediate frequency Δf as described above And then go back through the light path at the time of irradiation. However, unlike the illumination light, the detection light is converted into intensity modulation by the polarization beam splitter 22d, which is an analyzer, and reflected and guided upward in the drawing, and the image sensor 22h includes an image sensor provided in the measurement processing device 24h. An image is formed on the imaging surface.

  Further, the measurement processing device 24 of this configuration example integrally has the functions of the image sensor and the image processing device of the imaging device, and outputs the electric field distribution image obtained by the above-described various arithmetic processes to the image display device 25. Note that the image display device 25 can switch and display the video from the observation camera 26, and can easily confirm whether the specimen α and the electro-optic element 23 are appropriately arranged.

An example of the electric field distribution image obtained by the electromagnetic field high-speed imaging device 20 described above is shown in FIG. (A) is a two-dimensional image showing the electric field intensity distribution radiated from the specimen α, and (b) is a two-dimensional image showing the phase distribution. In the electromagnetic field high-speed imaging device 20, by setting the intermediate frequency Δf lower than the response frequency of the image sensor, even if the operating frequency f _RF of the specimen α is as high as several GHz, the behavior thereof The intermediate frequency Δf to which is transferred can be set to a frequency band to which the image sensor responds.

  Next, elemental techniques for acquiring a more suitable electromagnetic field distribution image in the above-described electromagnetic field high-speed imaging devices 10 and 20 will be described.

Magnitude of the difference frequency component Δf detected at each pixel of the image sensor 13c (square of amplitude), the product of the light intensity of the component generated by modulation by component and the frequency f _RF of the electromagnetic field of the same modulation frequency as the illuminating light Proportional. On the other hand, the light intensity of the detection light is the sum of these. In general, an image sensor cannot acquire an image when the intensity of saturated light is exceeded. Therefore, the detection sensitivity can be improved by increasing the product of the light intensity while keeping the light intensity below the saturation intensity. Specifically, using the fact that the polarization states of the modulated light having the two types of frequency components described above are orthogonal to each other immediately before the reflected light enters the polarizing beam splitter 22e, the quarter-wave plates 22e and 1 / By adjusting the two-wave plate 22f, the ratio between the two is optimized. Furthermore, by adjusting the intensity of illumination light from the light source and setting the light intensity detected by the image sensor 13c to an optimum intensity equal to or lower than the saturation light intensity, an image can be obtained with the maximum sensitivity of the image sensor 13c.

  As shown in the optical system arrangement diagram of FIG. 7, a wavefront matching optical system 33, a beam splitter 34 serving as both a polarizer and an analyzer, a connection are formed on the optical axis from the probe 31 arranged close to the specimen α to the image sensor 32. When the image optical system 35 is provided, parallel light parallel to the optical axis incident on the imaging optical system 35 from the probe 31 side is collected on the image sensor 32 side, that is, the image sensor 32 of the imaging optical system 35. If a fine light absorber 36 is arranged at the center of the opening at the infinity focal position on the side, a component 37 parallel to the optical axis of the reflected light from the probe 31 is absorbed by the light absorber 36. Noise incident on the imaging surface of the image sensor 32 can be reduced. Since the light absorber 36 is very small, the amount of the light beam 38 from the probe 31 that forms an image on the image sensor 32 is so small that the influence on the output of the image sensor 32 is small and the S / N ratio is increased. Bring.

  Further, as shown in the optical system arrangement diagram shown in FIG. 8, a wavefront matching optical system 43 and a beam splitter 44 serving as both a polarizer and an analyzer are arranged on the optical axis from the probe 41 arranged close to the specimen α to the image sensor 42. When the imaging optical system 45 is arranged, the parallel light parallel to the optical axis incident on the imaging optical system 45 from the probe 41 side is condensed on the image sensor 42 side, that is, infinite from the imaging optical system 46. If the image sensor 42 is disposed at the far focal position and the probe 41 is disposed at the other infinite focal position of the imaging optical system 45, a Fourier transform image of the reflected light of the probe 41 is formed on the image sensor 42. To do. The Fourier transform image is a Fourier transform image of the electromagnetic field distribution on the probe surface, that is, a far electromagnetic field image. If this configuration is used, a far electromagnetic field image of the electromagnetic field generated by the specimen α can be directly acquired.

It is a schematic functional block diagram of an electromagnetic field high-speed imaging device. It is a frequency distribution characteristic figure in the detection light from a probe. It is a functional block diagram of an image processing apparatus. It is an apparatus block diagram of an electromagnetic field high-speed imaging device. It is a schematic diagram explaining the effect | action of the wave front matching optical system and detection optical system of the optical system in FIG. (A) is a two-dimensional image showing the electric field intensity distribution radiated from the specimen. (B) is a two-dimensional image showing the phase distribution of the electric field radiated from the specimen. It is an optical system layout diagram in an electromagnetic field high-speed imaging device provided with a light absorber. It is an optical system layout diagram in an electromagnetic field high-speed imaging device capable of acquiring a far electromagnetic field image.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Electromagnetic field high-speed imaging device 11 Illumination device 12 Probe 13 Imaging device 13c Image sensor 14 Image processing apparatus (alpha) Sample

Claims (7)

A lighting device capable of outputting light modulated in amplitude at a frequency f _LO ;
The birefringence characteristic is locally changed by the electric field or magnetic field of the frequency f _RF emitted from the specimen to be measured, thereby causing a local polarization state in the light irradiated from the illumination device, and the frequency f _RF The illumination light from the illuminating device is further modulated by the near electromagnetic field and frequency-mixed, and the difference frequency component Δf between the modulation frequency f _{LO of the} light emitted from the illuminating device and the frequency f _RF of the electric field or magnetic field radiated from the specimen. A probe including an electro-optical element or a magneto-optical element capable of generating detection light including (| f _LO −f _RF |);
An imaging device that converts a local polarization state in the detection light from the probe into a local intensity of light and photoelectrically converts it to an imaging surface of an image sensor having a plurality of pixels; and
An image processing device that analyzes the distribution information of the near electromagnetic field radiated from the specimen using the difference frequency component Δf included in the pixel signal extracted for each pixel from the image sensor of the imaging device, and generates a two-dimensional image;
An electromagnetic field high-speed imaging device comprising:   The electromagnetic field high-speed imaging device according to claim 1, wherein a laser light source is used as a light source of the illumination device. Field fast according to claim 1 or claim 2 the reference frequency ΔfR frequency f _LO and the processing unit of the operating frequency f _RF and illumination device of the specimen is characterized in that so as to supply from the same oscillator signal Imaging device. The image processing apparatus includes:
Filtering means for passing a band including the difference frequency component Δf from the pixel signal output for each pixel from the image sensor of the imaging device;
A measuring device for analyzing the filtered output signal output from the filtering means;
With
The measuring device generates a reference sine wave and a reference cosine wave based on a reference signal supplied from a modulation signal source of the lighting device, and integrates the filtered output signal and the reference sine wave, Each of the filtered output signal and the cosine component integrated signal obtained by integrating the reference cosine wave is calculated, and amplitude information is calculated by calculating a sum of squares of the sine component integrated signal and the cosine component integrated signal. The electromagnetic field high-speed imaging device according to any one of claims 1 to 3, wherein the phase information is obtained by calculating a ratio with a cosine component integration signal.   5. The electromagnetic field high-speed imaging device according to claim 4, wherein the reference sine wave and the reference cosine wave generated by the measurement device are a pseudo reference sine wave and a pseudo reference cosine wave substituted by a rectangular wave.   The imaging apparatus includes an imaging optical system that forms a real image of the probe on an imaging surface of an image sensor, and a fine light absorber at the center of the aperture at the infinity focal position on the image sensor side of the imaging optical system The electromagnetic field high-speed imaging device according to claim 1, wherein the electromagnetic field high-speed imaging device is provided. Polarized light just before entering the analyzer by adjusting the polarization state control element with an illumination light source capable of high light output, analyzer and polarization state control element for the saturation light intensity of the image sensor The state is controlled, and the intensity ratio between the modulated light component generated in the probe of the detection light and the other components among the components included in the detection light transmitted through the analyzer can be adjusted. The electromagnetic field high-speed imaging device according to any one of claims 1 to 6.

Images