JPH04335140A - Weak-light measuring apparatus - Google Patents

Abstract

PURPOSE:To obtain isochrony of time change in space distribution and light intensity in measurement of resonance radiation light from ions, atoms and neutral particles by emitting cleaning light on the particles to be measured which are trapped in the space, cooling the particles, and emitting exciting light on the particles. CONSTITUTION:The ions supplied from an ion gun 14 are sent into the center of a pole trap through a pinhole 13a formed in a cap electrode 12a and held with an electric field. Then, cooling light is emitted. The energy of the cooling light is slightly lower than the intrinsic exciting energy of the ions which are held in the electric field. The ions are cooled to the extremely low temperature. Probe light having the same energy as the intrinsic energy is emitted on the cooled ions. The resonance radiation light generated from the ions are expanded with a lens 15 through a pinhole 13b and received with an imaging device. A slit plate 21 is provided at the input surface side of the imaging device. The radiation light from the particles to be measured through the slit is resolved in time-space and measured.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a weak light measuring device.
In particular, it relates to the measurement of resonant radiation from neutral particles such as extremely low temperature ions and atoms trapped in space.

0002

2. Description of the Related Art A photon counting image measurement system (PIAS) is known as a device for measuring the distribution of ions and atoms.
Technology”, Vol. 11, No. 5, P
．． 215-220 (1985). Furthermore, measurement techniques using ultra-high sensitivity imaging devices (VIM) are also known, such as those described in "Biophysics" Vol. 24, No. 4, P.
173-178 (1984).

On the other hand, as a measurement technique for measuring the light intensity of resonance synchrotron radiation and photon counting, a technique using a photomultiplier tube (PMT) is known.
View Letter"Vol.58, No.3,
P. 203-206 (1987).

0004

[Problems to be Solved by the Invention] However, the above-mentioned prior art has the following problems, and a solution to these problems has been desired.

First, with the former measurement techniques using PIAS and VIM, it is possible to image the measurement results, but it is difficult to time-resolve the emitted light. Furthermore, if the time range is less than a few ns, it will be limited by the response of the detector and measurement will become impossible.

[0006] Furthermore, in the latter measurement technique using PMT,
Although it is possible to measure with the temporal resolution raised to the sub-ns level, imaging is impossible because it is a zero-dimensional detection (point detection) method.

[0007] As described above, conventional measurement devices can only perform either imaging measurement or time-resolved measurement, so if you want to perform both measurements, you will need to use two sets of devices or It was necessary to make a change. However, in order to trap the particles to be measured in space and measure the synchrotron radiation, multiple laser beams for cooling the particles to be measured and a window for inputting one probe beam into the vacuum container are required. Therefore, it is difficult to install two sets of devices together. Furthermore, if the device is replaced, the simultaneity of the measurement data will be lost, making it impossible to obtain valid data. Therefore, the present invention focuses on ions, atoms,
When measuring resonance synchrotron radiation from neutral particles, we aim to provide a weak light measurement device that enables simultaneous measurement of their spatial distribution and temporal changes in light intensity, as well as photon statistics. purpose.

[0008]

[Means for Solving the Problems] A weak light measurement device according to the present invention includes a trap means for trapping a plurality of particles to be measured at a predetermined spatial position, and a trap means for trapping a plurality of particles to be measured at a predetermined spatial position, and a trap device having an excitation energy slightly lower than the original excitation energy of the particles to be measured. A cooling means for cooling the measured particles by irradiating them with cooling light, an excitation means for irradiating the measured particles with excitation light having the same energy as the original excitation energy, and a slit corresponding to at least a part of the excitation range by the excitation means. A measurement means for measuring the emitted light from the particles to be measured that has passed through the slit by time-spatial resolution.

[0009]

According to the structure of the present invention, the particles to be measured trapped in the space by the trap means are cooled by being irradiated with cooling light, and are irradiated with excitation light. Therefore, resonance radiation light is emitted from the particle to be measured and enters the measuring means through the slit. Therefore, it becomes possible to measure the spatial distribution within the range of the slit, and since the measuring means has a time-spatial resolution function, it becomes possible to measure changes over time. Moreover, if a spectrometer is further provided, spectroscopic analysis can be performed at the same time.

0010

EXAMPLES Prior to describing specific examples, the principle of the present invention will be briefly explained. By integrating a device for trapping particles to be measured and a device for measuring weak light, the device of the present invention enables simultaneous measurement of the spatial distribution and temporal change of weak light phenomena, which was previously impossible. It is unique in that it makes it possible.

First, there are two types of trap devices: an electromagnetic wave trap type and a laser trap type, and in these devices, a laser cooling method is generally used in combination. Trap devices using electric fields include Paul
Trap devices are known, for example, "Journal of the Physical Society of Japan" Vo.
l. 44, No. 3, P. 195-200 (1989)
and “Laser Research” Vol. 15, No. 10, P. 7
64-771 (1987). This pole trap device is applied to the weak light measurement device of the example, but the Pole Trap device is
) trap device (a trap device using a magnetic field) may be used, for example, as described in “Physics To
day” Vol. 40, No. 6, P. 34-40 (1
987).

On the other hand, a photon-counting streak tube can be used as the imaging device, that is, the weak light measuring device.
This is the case, for example, in US Pat. No. 4,611,920, British Patent No. 2,131,165, and also in
roceedings"Vol.693, P.98~1
04 (1986) and “Journal of Electrostatics Society” Vol. 14,N
o. 3, P. 202-211 (1990). Furthermore, as will be described in detail later, a masked CCD image sensor may be used.

[0013] By integrating the trap device and the measurement device in this way, it is possible to provide the function of imaging the resonant radiation light from ions, atoms, and neutral particles, which are weak lights, and also By performing a sweep, a space-time resolution function is provided. This allows us to measure the spatial distribution of ions, atoms, and various particles, observe their dynamics, and measure temporal changes in the resonant emitted light. moreover,
Photon statistical measurements of emitted light from a single ion, atom, or particle, and cross-correlation measurements of emitted light from multiple ions, atoms, or particles can be performed. Furthermore, by incorporating a device that can resolve wavelengths, such as a spectrometer, spectroscopic measurements become possible.

Hereinafter, specific embodiments will be explained with reference to the accompanying drawings.

FIG. 1 is a perspective view showing the overall configuration of a weak light measuring device according to an embodiment. As shown, the vacuum container 10
There are a ring electrode 11 and cap electrodes 12a, 12 inside.
b and a cap body 12c are provided, and the cap electrode 12a
A pinhole 13a is made in the center, and an ion gun 14 is attached to the pinhole 13a. A pinhole 13b is also formed in the center of the cap electrode 12b, and a magnifying lens 15 provided on the cap body 12c faces this pinhole 13b. Further, a voltage from a power supply device 16 is applied to the ring electrode 11 and the cap electrodes 12a and 12b via a connector 17, and an electric field for ion trapping is formed at the center. The vacuum container 10 is provided with a plurality of openings 18 through which a cooling laser beam (cooling light) and a flow probe laser beam (probe light) are incident. In this case, the probe light may be replaced by cooling light.

A slit plate 21 having slits is provided outside the vacuum container 10 at a position facing the magnifying lens 15, and a streak tube 30 is further provided with the lens 22 in between. A CCD camera 42 is provided on the output side of the streak tube 30 with a lens 41 in between.
The output of the CCD camera 42 is given to a television monitor 43.

The streak tube 30 includes an imaging lens 22.
a photocathode 31 formed on the input surface facing the photoelectrons, a mesh electrode 32 for extracting photoelectrons, a focusing electrode 33 for focusing photoelectrons, an anode 34 for accelerating photoelectrons, and a sweep voltage from a sweep circuit 44. a deflection electrode 35 to which is applied, a microchannel plate (MCP) 36 that multiplies the deflected photoelectrons, and a fluorescent surface 37 formed on the output surface.
and has. A predetermined voltage from a drive power source 45 is applied to each part such as the focusing electrode 33 and the anode 34.

Next, the functions and effects of each part of the weak light measuring device according to the above embodiment will be explained.

First, regarding the pole trap housed in the vacuum container 10, as shown in FIG. 12). Then, by applying a DC voltage Vo from the power supply device 16, a potential for confining ions is formed. The inner diameter of the ring electrode 11 is indicated by 2ro, and the distance between the cap electrodes 12 is indicated by 2zo.

For this pole trap, pinholes 13a and 13b are provided in the cap electrodes 12a and 12b, and
Ions are supplied from here, and cooling light is incident from an oblique direction. FIG. 3 shows this in cross-section. Ions supplied from the ion gun 14 are transferred to the cap electrode 1
It is sent to the center of the pole trap through a pinhole 13a formed in 2a, and is held (trapped) by an electric field. Cooling light is then irradiated, but the energy of this cooling light is slightly lower than the original excitation energy of the retained ions, and the ions are therefore cooled to an extremely low temperature. The cooled ions are irradiated with probe light having the same energy as the above-mentioned original energy, and the resonant radiation generated from the ions passes through the pinhole 13b and is magnified by the lens 15. , captured by the imaging device.

As shown in FIG. 1, this imaging device is composed of a photon-counting type streak camera, and a slit plate 21 having slits is provided on the input surface side thereof. Therefore, the ring electrode 11 and the cap electrode 1
A linear observation area is set in the trap space surrounded by 2a and 12b. In this configuration, two modes, a focus mode and a streak mode, can be adopted in this embodiment.

First, in the focus mode, the streak sweep in the streak tube 30 is stopped (the voltage applied between the deflection electrodes 35 is made zero), and the width of the slit of the slit plate 21 is widened. This results in a so-called focus mode, in which the image of the radiation source is enlarged and projected onto the fluorescent surface 37. If this is read out by the CCD camera 42, a photon counting image is obtained, which is similar to the VIM image described above. For this reason, the spatial distribution and fluctuation (motion) of trapped ions, atoms, particles, etc.
can be observed.

On the other hand, in the streak mode, a streak sweep voltage is applied to the deflection electrode 35, and the slit plate 2
Narrow the slit 1. Then, the first axis (horizontal axis) corresponds to the spatial axis, and the second axis (vertical axis) corresponds to the time axis. ) and a streak image showing time changes can be obtained. First, consider the case where we focus on photons emitted by one particle. In this case, photon images appearing at the same spatial axis coordinates in the streak image are analyzed. From such an image, the time interval between detected photons is measured and this data is processed. In other words, when a photon is detected at time t=T, the probability that the next photon will be detected at time t=T+τ; PS (τ)
And when a photon is detected at time t=T, time t=T+
The probability that a photon is detected at τ; PC (τ) is determined. From these mathematically equivalent PS (τ) and PC (τ), it is possible to determine the nature of the light source, that is, incoherent light, coherent light, and sub-Poisson light. The statistical distribution of the number of photons observed within a certain period of time may also be measured. moreover,
Since the streak camera stores spatial direction information, the above-mentioned "Journal of Electrostatics Society" Vol. 14, No. 3,P
．． Spatio-temporal resolved measurements as shown in 208 can be performed. This means that time-resolved measurement of photon radiation is performed for each position along a straight line on the object to be measured.

The above-mentioned streak image appears as a fluorescent image on the fluorescent surface 37 and is captured by the CCD camera 42. The video signal is then applied to the television monitor 43 and displayed on the CRT screen. According to the above device, the cross-correlation of photons emitted from individual ions can be measured. From this, it is possible to observe the phase-locked state of resonant radiation from each ion, atom, and particle. Alternatively, the video signal of the CCD camera may be converted into a digital signal, stored in an image memory (not shown), integrated, and subjected to various image processing to display the results.

The present invention is not limited to the above-mentioned embodiments, but can be modified in various ways.

First, as a trap device, a Penning trap as shown in FIG. 5 may be used. This uses a magnetic field to hold particles in space, and like the pole trap, laser beam cooling is also used. As for the imaging device, for example, a photon counting streak camera may be used. Alternatively, a trap as shown in FIG. 6 may be used. This is “Optics Lette
rs” Vol. 15, No. 11, P. 607 (199
0), the atoms from the atomic gun (indicated by dotted lines) are blown into the Dove by a magnetic field and six morass beams.
Trapped above the prism. Although this trap device uses trampoline cooling, it can also measure the vibrations and movements of ions, atoms, and particles, and control the cooling process based on this movement data. This kind of cooling control is possible by feeding back observation data of trampoline movement to optical power, etc., and controlling trampoline movement. Proceedings of the 8th Annual Conference of the Society 18aIV5, p. 15
It is shown in ~.

As for the imaging device, in addition to the streak camera device, for example, a CCD image sensor may be used as a solid-state imaging device. The photoelectric conversion unit of a CCD image sensor is a photodiode, which stores charges obtained through photoelectric conversion in a potential well created in a semiconductor, and reads out signal charges by sequentially moving the position of this potential from the outside. Such a CCD has both signal storage and scanning functions. The CCD image sensor has
frame transfer (FT)
)・Interline transfer (interline tra
nsfer, IT)/frame interline transfer (fr
ame interline transfer,
FIT) method, and their structure is shown in FIG. In the frame transfer method, a light receiving section and a transfer section are provided separately, and signal charges converted and accumulated in the light receiving section are transferred at high speed to the transfer section within the vertical retrace period, and are sequentially read out. In the interline transfer method, a transfer section is provided next to the light receiving section, and although the closing rate of the light receiving section is about 50%, the charge transfer efficiency is good. Further, the frame interline transfer method has recently been developed, and some allow shutter operation of 1/60 to 1/2000 seconds.

In the present invention, when performing normal imaging, the CCD image sensor shown in FIG. 7 may be used as is. When performing spatial and temporal resolved imaging,
Leaving only the top of the photosensitive area, the lower side from the position indicated by the dotted line in FIG. 7 is optically masked. Then, it is sufficient to image the emitted light in the form of a slit only on the photosensitive section at the top. However, the vertical shift is driven by a clock determined based on the required time resolution. In this case, the two types of imaging modes described above can be obtained by mechanically introducing the optical mask. However, if time resolution at the single photon level is required, it is necessary to use an element with gain, such as an avalanche photodiode, as the photosensitive section.

[0029]

As described above in detail, according to the configuration of the present invention, the particles to be measured trapped in the space by the trap means are cooled by being irradiated with cooling light, and are irradiated with excitation light. be done. Therefore, resonance radiation light is emitted from the particle to be measured and enters the measuring means through the slit. Therefore, in the so-called focus mode, it is possible to measure the spatial distribution within the slit range.
Furthermore, since the measuring means in the streak mode has a temporal and spatial resolution function, it is possible to measure temporal changes. Moreover, if a spectrometer is further provided, spectroscopic analysis can be performed at the same time.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the overall configuration of a weak light measurement device according to an embodiment.

FIG. 2 is a diagram showing the structure of a pole trap.

FIG. 3 is a diagram showing the relationship between a trap device, an ion gun, and an imaging device in the weak light measurement device of the example.

FIG. 4 is a diagram showing the relationship between a slit and a streak camera.

FIG. 5 shows a Penning trap.

FIG. 6 is a diagram showing another example of a trap device.

FIG. 7 is a diagram showing an example of a CCD image sensor applicable to the weak light measurement device of the present invention.

[Explanation of symbols]

10...Vacuum container 11...Ring electrode 12...Cap electrode 13...Pinhole 14...Ion gun 15...Magnifying lens 16...Power supply device 21...Slit plate 30...Streak tube 31...Photocathode 37...Fluorescent surface 42...CCD camera 43...TV monitor

Claims (7)

[Claims] 1. A trap means for trapping a plurality of particles to be measured at a predetermined spatial position, and irradiating the particles to be measured with light having an energy substantially equivalent to the original excitation energy of the particles to be measured, and cooling the particles to be measured. It has a light irradiation means for exciting the particle to be measured, and a slit corresponding to at least a part of the excitation range by the light irradiation means, and the emitted light from the particle to be measured that has passed through the slit is resolved in time and space. 1. A weak light measuring device comprising: a measuring means for measuring. 2. Trap means for trapping a plurality of particles to be measured at a predetermined spatial position, and cooling light that is slightly lower in energy than the original excitation energy of the particles to be measured and cooled by irradiating the particles to be measured. a cooling means, an excitation means for irradiating the measured particle with excitation light having the same energy as the original excitation energy, and a slit corresponding to at least a part of the excitation range by the excitation means,
A weak light measuring device characterized by comprising a measuring means for measuring the emitted light from the particle to be measured that has passed through the slit by time-spatial resolution. 3. The weak light measuring device according to claim 1, further comprising a spectroscopic means for separating the light emitted from the particle to be measured and incident on the measuring means. 4. The weak light according to claim 1, wherein the measuring means has a streak tube that performs temporal and spatial resolution by sweeping photoelectrons emitted when the synchrotron radiation is incident on a photocathode. Measuring device. 5. The measuring means includes a solid-state imaging device that performs temporal and spatial resolution by transferring charges generated by the radiation light incident on a photoelectric conversion element at a predetermined clock. 3. The weak light measuring device according to 3. 6. Claims 1 and 3, wherein the cooling by the light irradiation means is controlled using the measurement result by the measurement means.
, 4 or 5, the weak light measurement device. 7. Cooling by the cooling means is controlled using the measurement result by the measuring means.
5. The weak light measuring device according to 4 or 5.