JP7034485B2 - Electromagnetic wave measuring device - Google Patents

Description

The present invention relates to, for example, an electromagnetic wave measuring device for measuring an operating state of an electronic circuit, and in particular, by irradiating an atom enclosed in an arbitrary cell with a specific laser beam or an invisible wave, the quantum state is relayed between the quantum states. The present invention relates to an electromagnetic wave measuring device that realizes multiple resonances to be connected and measures electromagnetic waves by utilizing the intensity of fluorescence and the spatial distribution according to the excitation energy received from laser light or the like.

In Patent Document 1, the electromagnetic field strength is calculated based on the electromagnetic field information acquired by the electromagnetic field sensor, and the electromagnetic field vector is calculated using the calculated electromagnetic field strength to display the electromagnetic field vector in three dimensions. It describes what to do.
Patent Document 2 describes measuring the radio field intensity for each measurement region by using measuring members arranged in a plurality of measurement regions.

Japanese Unexamined Patent Publication No. 2012-042401 Japanese Patent No. 5737672

Conventionally, the electromagnetic wave intensity has been measured by using a wattmeter, an antenna, etc. arranged in the circuit, but there are limits in terms of cost and accuracy. Further, as a technique for visualizing electromagnetic waves, a technique using a scanning sensor or a two-dimensional array sensor has been developed, but these require a reasonable sweep time and have a limit in pixel size.
That is, in order to measure the intensity distribution of electromagnetic waves, it is common to sweep minute sensors spatially, or to arrange a large number of minute electromagnetic wave sensors in space, but a finite sweep. High speed is lost due to time, and resolution and sensitivity are limited due to limited sensor dimensions.

Therefore, the inventors focused on the fact that when an atom is irradiated with an electromagnetic wave, the internal state of the atom repeatedly changes to generate Rabi vibration, and its frequency (rabbi frequency) depends on the intensity of the electromagnetic wave irradiated to the atom. However, we have developed an electromagnetic wave measurement technology that utilizes this.
(https://www.nmij.jp/public/ResearchTopics/pdf/2016_12_No1.pdf)
In this electromagnetic wave measurement technology, as an example, a glass cell containing a gaseous cesium atom is inserted into this waveguide for an electromagnetic wave of 9.2 GHz transmitted in the waveguide, and its behavior is observed with laser light. The rabbi frequency was measured in Japan, and it was verified that the measurement result by a specific standard in Japan was in agreement with the measurement result within the range of uncertainty.

This electromagnetic wave measurement technology, which mainly uses glass cells and laser light detection, makes it possible to measure the intensity distribution in a narrower range than the wavelength of electromagnetic waves, which was difficult with ordinary antenna measurement, and with high accuracy. Since it is wireless, it also has the advantage of not being subject to the reflection of electromagnetic waves by cables and physical constraints.

Therefore, an object of the present invention is to further deepen this electromagnetic wave measurement technique, for example, it can be directly incorporated into a circuit board manufacturing line, and moreover, an actually measured value of an electromagnetic wave intensity distribution in a two-dimensional plane or a three-dimensional space to be measured. Is to be able to measure at low cost, speed, and with high accuracy.

In the electromagnetic wave measuring device of the present invention for solving the above-mentioned problems, a glass cell is a glass cell arranged at a predetermined position with respect to a measurement target, and a rabbi that repeatedly changes the state inside the atom by irradiation with electromagnetic waves generated from the measurement target. A glass cell having a sealed space in which atoms that generate vibration are enclosed, and a laser beam having a light pumpable wavelength for the atoms inside the sealed space to absorb microwaves of a specific frequency are measured from the side surface of the glass cell. A first laser irradiation device and a second laser irradiation device that irradiate the inside of a sealed space along the surface of an object, an image pickup device that photographs the surface of a glass cell, a first laser irradiation device, a second laser irradiation device, and an image pickup. The processing device is provided with a processing device connected to the device, and the processing device is an electromagnetic wave having a specific frequency irradiated to an atom in a state where the image pickup device performs optical pumping with the first laser beam emitted from the first laser irradiation device. The first laser beam is described in a state where the two-dimensional intensity distribution of near-infrared fluorescence generated by the absorption and reabsorption of the first laser is imaged and the light pumping is performed by the first laser irradiation device and the second laser irradiation device. Based on the image pickup result by the image pickup device at the intersection of the second laser beam emitted from the second laser irradiation device, the processing device measures the measured value of the electromagnetic wave intensity at a specific point on the two-dimensional plane of the glass cell, and near. Based on the two-dimensional intensity distribution of infrared fluorescence and the measured value of the electromagnetic wave intensity at a specific point, the measured value of the electromagnetic wave intensity distribution on the two-dimensional plane of the glass cell is calculated.

According to the present invention, it is possible to measure the measured value of the electromagnetic wave intensity distribution in the two-dimensional plane of the glass cell by photographing the fluorescence emitted by the atoms enclosed inside the glass cell by the action with the electromagnetic wave with a camera. Therefore, it is possible to realize high-resolution electromagnetic wave intensity measurement in real time over a wide range.

FIG. 1 is a bird's-eye view of an electromagnetic wave measuring device based on the present invention. FIG. 2 is a plan view of an electromagnetic wave measuring device based on the present invention. FIG. 3 is a diagram schematically showing fluorescence generated on the surface of a glass cell when optical pumping by laser light irradiation is performed. FIG. 4 shows a photographed image of the generated fluorescence. FIG. 5 is a schematic diagram when the present invention is applied to the measurement of the intensity distribution of electromagnetic waves radiated from a horn antenna into space.

1 and 2 show an outline of an embodiment based on the present invention, FIG. 1 is a bird's-eye view, and FIG. 2 is a plan view.
The electromagnetic wave measuring device of this embodiment has a glass cell 2, a first laser irradiation device 3, a concave lens 4, and a second mounted on the surface of a measurement target 1 such as a circuit board in a state of being positioned by a jig or the like. It is composed of a laser irradiation device 5, a laser receiver 6, a shift device 7 for moving the concave lens 4 back and forth, an image pickup device 8 for photographing the surface of the measurement target 1, a processing device 9 provided with a display, and the like.

A sealed space is formed inside the glass cell 2, and cesium in a state where the saturated vapor pressure is maintained is sealed in this sealed space. The glass cell 2 is preferably formed of synthetic quartz or commercially available heat-resistant glass, and in this embodiment, a sealed space of 100 mm in length × 100 mm in width × 10 mm in height is formed.

The first laser irradiation device 3 is installed toward the side surface 2a of the glass cell 2, and the irradiated laser light is diffused toward the side surface 2a of the glass cell 2 via the concave lens 4 and inside the glass cell 2. The diffused laser beam is irradiated over the entire sealed space of the.
On the other hand, the second laser irradiation device 5 is installed toward the side surface 2b of the glass cell 2 orthogonal to the side surface 2a, and the irradiated laser light is emitted from the first laser irradiation device 3 in the sealed space of the glass cell 2. The laser beam emitted from the glass cell 2 intersects with the side surface 2a of the glass cell 2.

In this embodiment, the glass cell 2 is placed so as to be in close contact with the microwave circuit (microstrip line) substrate as the measurement target 1.
Next, a laser beam having a wavelength of 852 nm is irradiated from the first laser irradiation device 3 so that the cesium atom absorbs an electromagnetic wave of 9.2 GHz (hereinafter, also referred to as “microwave”). This laser beam spreads over the entire width of the side surface 2a while maintaining parallelism to the surface of the glass cell 2 by the concave lens 4, and diffuses over the entire sealed space in the glass cell 2 with respect to the cesium atom in the sealed space. Perform optical pumping.

In this state, when the cesium atom absorbs the microwave, it absorbs the laser beam having a wavelength of 852 nm again and instantly emits fluorescence having a wavelength of 852 nm as shown in the schematic diagram of FIG. This fluorescence is photographed by an image pickup device 8 such as a CCD camera having high sensitivity to near infrared light. Thereby, the relative two-dimensional intensity distribution of the microwave in the microwave circuit 1 can be obtained as the intensity distribution of near-infrared fluorescence.
FIG. 4 shows an actual photographed image, and it can be confirmed that the relative electromagnetic wave intensity distribution on the microwave circuit 1 is visualized and that the near-infrared fluorescence intensity distribution of the cesium atom reflects the electromagnetic wave intensity distribution. ..
The intensity distribution of the electromagnetic wave obtained from this image clearly shows the standing wave caused by the reflection in the microwave circuit and matches the theoretical wavelength and phase, and the infrared light image is micro. It was found that the wave intensity distribution was reflected in real time and the resolution was below the wavelength. Further, if the sealed space inside the glass cell 2 is heated by using a heater or the like, the density of cesium atoms can be increased and a clearer infrared light image can be obtained.

Next, the processing device 9 sends a command signal to the shift device 7, and the laser beam emitted from the first laser irradiation device 3 (hereinafter referred to as “the first”) in a state where the concave lens 4 is moved out of the optical path of the laser beam. (Also referred to as "1 laser beam") is applied to the inside of the sealed space from one point on the side surface 2a of the glass cell 2, and the laser beam emitted from the second laser irradiation device 5 (hereinafter, also referred to as "second laser beam"). Will intersect at one point.
At that time, the processing device 9 sends a control signal to the first laser irradiation device 3, and the second laser beam is modulated by either amplitude modulation (AM), frequency (FM), or phase modulation (PM). The first laser beam transmitted through the glass cell 2 is detected by the laser receiving device 6, and the transmitted light intensity is measured.

Since the transmitted light intensity of the first laser light is also modulated by the modulation of the second laser light, the modulation depth of the first laser light is measured by the laser receiver 6 while changing the modulation frequency of the second laser light. do.
Here, the modulation depth of the first laser beam depends on the difference between the modulation frequency of the second laser beam and the rabbi frequency. Therefore, the rabbi frequency indicating the absolute intensity of the electromagnetic wave at the intersection of the first laser beam and the second laser beam can be measured from the waveform of the graph showing the modulation depth of the first laser with respect to the modulation frequency of the second laser beam. ..

In this way, based on the relative electromagnetic wave intensity distribution on the microwave circuit 1 measured only by the first laser irradiation device 3 described above with reference to the absolute value of the electromagnetic wave intensity, the electromagnetic wave intensity distribution on the microwave circuit 1 is absolutely determined. The intensity can be calculated, and it can be used as a performance tester for the microwave circuit 1.

In the above embodiment, the concave lens 4 is used to measure the relative intensity distribution of the electromagnetic wave using the infrared light image obtained by the irradiation of the first laser beam, but the first laser is not used without the concave lens 4. A first scanning device for scanning the irradiation device 3 along the side surface 2a of the glass cell 2 is provided, relative electromagnetic wave intensity distribution measurement is performed only by the first laser irradiation device 3, and the first laser irradiation device 3 and the second laser are used. The absolute intensity of the electromagnetic wave may be measured by simultaneous irradiation of the irradiation device 5.
At that time, if the second laser irradiation device 5 is also scanned along the side surface 2b of the glass cell 2 by the second scanning device, the absolute value of the electromagnetic wave intensity at any point of the glass cell or the whole is measured. It becomes possible.

When the relative intensity distribution of the electromagnetic wave is measured by using the infrared light image obtained by the irradiation of the first laser beam and the absolute intensity of the electromagnetic wave is measured by the irradiation of the second laser beam using the concave lens 4. 1 It is necessary to correct the intensity of the laser beam and the non-uniformity of the static magnetic field at the measurement point. However, when the first laser irradiation device 3 and the second laser irradiation device 5 are shifted and scanned, such correction is not necessary. However, since the spatial resolution is determined by the size of the intersection and the number of scanning points, the time required for scanning is required to obtain the same resolution as the infrared light image.

In the above embodiment, cesium is sealed in the glass cell 2, but rubidium or the like can also be used. In the case of rubidium, the wavelength of the laser beam is 780 nm, which is more general than 852 nm of cesium, but the wavelength of the electromagnetic wave that can be visualized also differs depending on the atom, so the atom is selected according to the application.

Further, in the above embodiment, the glass cell 2 is placed in close contact with the measurement target and the two-dimensional distribution of the electromagnetic wave is measured. However, in the electromagnetic wave measurement environment, the glass cell 2 is shifted in the height direction and the glass cell 2 is measured. A three-dimensional distribution can be obtained by integrating the two-dimensional intensity distributions obtained each time.
In this case, the processing device 9 cooperates with a positioning device such as a robot hand that controls the three-dimensional position of the glass cell 2, measures the above-mentioned two-dimensional distribution of electromagnetic waves for each height of the glass cell 2, and integrates them. By doing so, the three-dimensional distribution of electromagnetic waves is calculated and displayed on the display. By visualizing the radiation pattern of electromagnetic waves in this way, it can be applied to antenna design / development and EMC.
Although the measurement range in the height direction is limited, the height of the glass cell 2 and the sealed space formed inside the glass cell 2 is expanded, and the first laser irradiation device 3 and the second laser irradiation device 5 are positioned as described above. It is also possible to measure the three-dimensional intensity distribution of electromagnetic waves within the height range of the sealed space by shifting in the height direction using.

In the above embodiment, the glass cell 2 is placed so as to be in close contact with the measurement target, and the two-dimensional distribution of the electromagnetic wave generated from the measurement target is measured. As shown in FIG. 5, the glass cell 2 is mounted on the horn antenna 10. The intensity distribution of microwaves radiated from the antenna into space by arranging the front surface can also be obtained as the intensity distribution of near-infrared fluorescence.
Furthermore, using multiple resonance technology, in the state of optical pumping with a laser beam with a wavelength of 852 nm so that the above-mentioned cesium atom absorbs the microwave of 9.2 GHz, in addition to the microwave of 9.2 GHz from the horn antenna, further cesium By giving a low frequency band microwave corresponding to the energy difference between the Zeeman sublevels with a loop coil antenna, the fluorescence corresponding to the low frequency band microwave can be observed in real time with the same image pickup device 8. Is also possible.
According to the actual observation results, it was confirmed that the microwave intensity distribution in the vicinity of the horn antenna obtained by the electromagnetic field simulator also matches.

1; Measurement target 2; Glass cell 3; First laser irradiation device 4; Concave lens 5; Second laser irradiation device 6; Receiver device 7; Shift device 8; Image pickup device 9; Processing device 10; Horn antenna

Claims (6)

A glass cell that is placed at a predetermined position with respect to the measurement target and has a sealed space in which atoms that generate Rabi vibration that repeatedly changes the state inside the atom due to irradiation of electromagnetic waves generated from the measurement target are enclosed. When,
From the side surface of the glass cell, a laser beam having a wavelength capable of optical pumping for atoms inside the sealed space to absorb microwaves of a specific frequency is irradiated to the inside of the sealed space along the surface of the measurement target. The first laser irradiation device and the second laser irradiation device,
An image pickup device that photographs the surface of the glass cell, and
Equipped with a processing device,
The processing apparatus absorbs electromagnetic waves of a specific frequency irradiated to the atoms and reabsorbs the first laser beam in a state of performing optical pumping by the first laser beam emitted from the first laser irradiation apparatus. The two-dimensional intensity distribution of the electromagnetic wave is measured based on the image pickup result of the near-infrared fluorescence generated by the image pickup device, and the light pumping is performed by the first laser irradiation device and the second laser irradiation device. , The electromagnetic wave at the specific point in the two-dimensional plane of the glass cell based on the intensity of the light transmitted by the first laser light intersecting the second laser light emitted from the second laser irradiation device at a specific point. Measure the absolute value of the intensity and
An electromagnetic wave measuring device characterized in that the absolute value of the electromagnetic wave intensity distribution in the two-dimensional plane of the glass cell is calculated based on the two-dimensional intensity distribution of the electromagnetic wave and the absolute value of the electromagnetic wave intensity at the specific point. When determining the two-dimensional intensity distribution of the near-infrared fluorescence, the first laser irradiation device and the glass cell so as to diffuse and irradiate the first laser beam from the side surface of the glass cell over the entire area of the sealed space. The electromagnetic wave measuring apparatus according to claim 1, wherein a concave lens is interposed between the side surface of the glass and the surface of the device. The electromagnetic wave measuring device according to claim 1, wherein a first scanning device for scanning the first laser irradiating device is provided so as to irradiate the first laser beam along the side surface of the glass cell. The second or third aspect of the present invention, wherein the second scanning device for scanning the second laser irradiating device is provided so as to irradiate the second laser beam along the other side surface of the glass cell. Electromagnetic wave measuring device. Claims 1 to 4 are characterized in that the glass cell is shifted in the height direction in an electromagnetic wave measurement environment to obtain a three-dimensional distribution by integrating the two-dimensional intensity distributions obtained each time. The electromagnetic wave measuring device according to any one of the above items. The measurement target is a horn antenna, and by applying a low-frequency band microwave corresponding to the energy difference between the Zeeman sub-levels of the atom with a loop coil antenna, fluorescence corresponding to the low-frequency band microwave can be obtained. The electromagnetic wave measuring device according to any one of claims 1 to 5, wherein the image is captured by an image pickup device.

Images