JPH056122B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical waveform observation device for observing the waveform of an optical pulse having a constant repetition frequency.

[Conventional technology]

Conventionally, in order to observe the waveform of a light pulse with a constant repetition frequency, a method has been used that uses a streak tube to convert the temporal changes in the light pulse into a brightness distribution, that is, a streak image, on a fluorescent surface, and then performs sampling. Optical waveform observation devices are known.

FIG. 10 is a block diagram of a conventional optical waveform observation device as disclosed in US Pat. No. 4,645,918. The hematoporphyrin derivative 104 is repeatedly excited by a pulsed light beam repeatedly output from the dye laser oscillator 101, and the waveform of fluorescence emission from the repeatedly excited hematoporphyrin derivative 104 is observed using the streak tube 130. I'm starting to do that. In FIG. 10, a streak tube 130 includes a photocathode 131 on which fluorescent light is incident, an accelerating electrode 135 that accelerates an electron beam emitted from the photocathode, and a focusing tube that focuses the electron beam accelerated by the accelerating electrode 135. electrode 136, perforated electrode 137, focusing electrode 136 and perforated electrode 137
a deflection electrode 133 for sweeping the electron beam focused and passed by the deflection electrode 133; a microchannel plate 132 for multiplying the electron beam swept by the deflection electrode 133; and the electron beam from the microchannel plate 132 is incident. A fluorescent surface 134 is provided.

A pulsed light beam repeatedly output from the dye laser oscillator 101 is split by a beam splitter 102, and one of the pulsed light beams repeatedly excites the hematoporphyrin derivative 104 to keep the fluorescence emission from the hematoporphyrin derivative 104 constant. The light is made incident on the photocathode 131 of the streak tube 130 via the optical system 116 at a repetition frequency of . The other light beam split by the beam splitter 102 is sent to a photodiode 10 in order to generate an electric signal TR for a predetermined deflection voltage to be applied to the deflection electrode 133 of the streak tube 130.
It is starting to join the number 5. The photodiode 105 photoelectrically converts the pulsed light beam into an electric trigger signal TR. The electric trigger signal TR from the photodiode 105 is transmitted to the control circuit 1.
The deflection trigger signal is delayed by the time sweep circuit 107 under control from the deflection circuit 10.
It is starting to join the number 8. The deflection circuit 108 generates a deflection voltage synchronized with the deflection trigger signal.

In addition, the streak tube 130 sweeps the electron beam emitted from the photocathode 131 with a deflection voltage applied to the deflection electrode 133, thereby measuring temporal changes in the fluorescence emitted incident on the photocathode 131 spatially on the fluorescent surface 134. It is now possible to convert this into a brightness distribution and observe it as a streak image. In the optical waveform observation device shown in FIG.
is input to the sampling plate 111 through the slit 109 of the sampling plate 111 and extracted as a sampling waveform.
The sampling waveform is photoelectrically converted and multiplied by a photomultiplier tube 112, and then outputted to a display device 114 via a multiplier 113.

The operation of the optical waveform observation device with such a configuration is described in the first section.
This will be explained using the time charts shown in Figures 1a to 1e.

Due to the pulsed light beam repeatedly output from the dye laser oscillator 101, the hematoporphyrin derivative 104 outputs fluorescent light emission with a repetitive period as shown in FIG. 11a, that is, incident light IN.
The light is incident on the photocathode 131 of the streak tube 130.
On the other hand, the photodiode 105 outputs an electric trigger signal TR as shown in FIG. 11b by the pulsed light beam from the dye laser oscillator 101. As can be seen from FIGS. 11a and 11b, the electric trigger signal TR is completely synchronized with the incident light IN. The electrical trigger signal TR is further converted into a gradually delayed deflection trigger signal as shown in FIG. 11c by a time sweep circuit 107. 11th
In Figure c, the deflection trigger signal TR1 at the n-th sampling timing is the electrical trigger signal TR
delayed by time n·t, the (n+1)th time,
The deflection trigger signals TR2 and TR3 at the (n+2)th sampling timing are (n+1)·t and (n+2)·t with respect to the electric trigger signal TR.
Each is delayed by t. Note that t is a unit delay time of the deflection trigger signal. When these deflection trigger signals are applied to deflection circuit 108, deflection circuit 108 generates a deflection voltage V as shown in FIG. 11d. As can be seen from FIG. 11d, the deflection voltage V
is held at the potential V _n when the electron beam emitted from the photocathode 131 is not swept, and changes from the potential V _n to the potential −V _n when the deflection trigger signal is applied.
It is designed to descend at a nearly constant inclination up to the point where it sweeps the electron beam. Due to such a drop in the deflection voltage V, the electron beam is swept from above to below, and streak images FG1 and FG are formed on the fluorescent surface 134 at each sampling timing as shown in FIG. 11e.
2, observed as FG3. That is, the incident light IN
The temporal change in intensity can be observed as a luminance distribution. As is clear from the comparison between Figures 11a and 11e, each streak image FG1, FG
2. FG3 reflects the waveform of the incident light IN, but the streak images FG1, FG2, and FG3 are out of phase with each other because the phase of the deflection transformer V shifts at each sampling timing. It's summery. While sweeping the electron beam, when the deflection voltage V is near "0" V, the electron beam is not deflected and reaches the center of the fluorescent surface 134;
A light beam emitted from the center of the sampling electrode 111 mainly passes through the slit 109 of the sampling electrode 111, and is detected by the photomultiplier tube 112 as a sampling signal. That is, as shown in FIG. 11e, at the n-th, (n+1)-th, and (n+2)-th sampling timings, the sampling signals P1, P2, and P3 are extracted by the slit 109 of the sampling plate 111 and photoelectron multiplied. Detected in tube 112.

In this way, the sampling signals P1,
By sequentially detecting P2 and P3 and combining these sampling signals, one pulse waveform of the incident light IN having a repetition frequency can be observed with a predetermined time resolution.

Note that FIG. 10 shows a sampling electrode 1 having a slit 109 on the outside of the streak tube 130.
11, but the streak tube 1 shown in FIG.
50, a sampling electrode 151 may be provided inside this streak tube 150, that is, between the microchannel plate 132 and the fluorescent surface 134. In FIG. 12, sampling electrode 151 is held at the same potential as fluorescent surface 134. In FIG. A streak tube having a sampling electrode therein is generally referred to as a sampling streak tube. Sampling streak tube 1
50, the electron beam is directed to the fluorescent surface 13.
4, the sampling waveform can be extracted before reaching the center of the fluorescent surface 134, compared to the case of the optical waveform observation device shown in FIG. It is possible to input the necessary electron beam only to a portion of the photoelectron beam, and send only a portion of the luminance distribution to the photomultiplier tube 112.
A sampling waveform with less background noise from the fluorescent surface can be detected.

[Problem that the invention seeks to solve]

By the way, in the streak tube 130 shown in FIG. 10 or the sampling streak tube 150 shown in FIG. Contains noise. That is, the aperture ratio of the mesh of the accelerating electrode 135 is normally 60%, and as shown in FIG. The light is scattered by the non-opening portion of the mesh and becomes scattered light DF, which enters the photocathode 131 from behind again and emits photoelectrons BG, becoming background noise. Figure 13b
represents the electron density distribution ρ that has reached the sampling electrode 151 in the streak tube 150. As can be seen from FIG. 13b, when the mesh-shaped accelerating electrode 135 is used, the electron density distribution ρ includes a density distribution P _e due to photoelectrons of scattered light, in addition to a density distribution ρ _O due to signal electrons. However, this density distribution ρ _e becomes background noise and reduces the observation accuracy of the sampling waveform.
As can be seen from the density distribution P _e , the photoelectron BG due to scattered light peaks at the position of the incident light and gradually decreases toward the periphery, but the amount becomes considerable in areas close to the incident light, deteriorating measurement accuracy. As a result, for example, when measuring an optical pulse that is sufficiently shorter than the time resolution of the system, background noise due to scattered light DF occurs before and after the measured optical pulse, making it impossible to accurately measure the optical pulse waveform.

Furthermore, since such background noise, that is, the density distribution ρ _e , has a large spread, the probability of being sampled is low even when incident light is incident on the photocathode 131 during the period when the electron beam is not swept, that is, during the standby time. It is desirable to remove this because it reduces the observation accuracy of the sampled waveform. For this reason, in the conventional optical waveform observation device, the deflection voltage V output from the deflection circuit 108 is set to have a large amplitude and a high slew rate (voltage/time). That is, by setting the deflection voltage V to have a large amplitude and a high slew rate, it is possible to reduce the probability that photoelectrons due to scattered light will be sampled during sweeping of the electron beam. In addition, by increasing the amplitude of the deflection electrode V, the voltage V _n of the deflection voltage V during the time when the electron beam is not swept is
For example, even if incident light is incident on the photocathode 131 during this period, the signal electrons due to this incident light will be largely deflected by the deflection electrode 133 and will be reflected on the fluorescent surface 134 of the streak tube 130 shown in FIG. Since most of the photoelectrons of the scattered light are also incident at a position far from the center of the fluorescent surface 134, the density distribution of photoelectrons due to the scattered light ρ _e Even if the light becomes large and spread out, the probability of the light entering the center of the fluorescent surface 134 decreases, and it is possible to prevent the influence on the sampling waveform. Also the 12th
Also in the sampling streak tube 150 shown in the figure, by increasing the deflection potential V _n , the electron beam during the non-sweeping period is
1, since the light is incident at a position quite far away from the slit, it is possible to similarly prevent the influence of scattered light photoelectrons on the sampling waveform.
Specifically, the potentials V _n and −V _n of the deflection voltage V are +
It is about 1KV, -1KV.

On the other hand, in an optical waveform observation device that attempts to observe the waveform of incident light by sampling, the electron beam emitted from the photocathode 131 by the incident light crosses the slit of the sampling electrode 151 due to deflection at a speed v _t , the thickness of the electron beam u, and the slit width of the sampling electrode 151 w
determines the aperture time, that is, the time Δt at which the sampling waveform is extracted, and this aperture time Δt corresponds to the time resolution. Aperture time Δt
is expressed as Δt=√( ² + ² )/ _vt ...(1), and the sweep speed _vt is the deflection sensitivity of the sampling streak tube 150 as S (cm/V),
If the slew rate of the deflection voltage is T (V/sec), it is expressed as v _t =S×T (2).

Therefore, from equations (1) and (2), the aperture time Δt is
It can be seen that by increasing the deflection sensitivity S and the slew rate T of the deflection voltage, the time can be shortened and the time resolution can be improved.

However, in the conventional optical waveform observation device, when trying to improve the deflection sensitivity S by reducing the distance between the pair of deflection electrodes 133, the deflection voltage V is made to have a large amplitude, resulting in a period during which no sweeping is performed. A situation occurs in which the largely deflected electron beam collides with the deflection electrode 133, is reflected, and enters the center of the fluorescent surface 134. Therefore, in the conventional optical waveform observation device, it is not possible to make the interval between the deflection electrodes 133 significantly smaller, and there is a limit to the ability to significantly improve the deflection sensitivity S. For example, it is not possible to obtain a time resolution of several picoseconds. Furthermore, there was a problem in that it was not possible to increase the repetition frequency of deflection.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical waveform observation device that can prevent the influence of background noise on a sampling waveform, significantly improve deflection sensitivity, and realize high-speed repetitive deflection.

[Means for solving problems]

The present invention improves a type of optical waveform observation device that uses a sampling streak tube to observe the waveform of incident light having a constant repetition frequency.

The first invention is that the sampling streak tube is
A photocathode on which incident light enters, an accelerating electrode that accelerates the electron beam emitted from the photocathode, a deflection electrode that sweeps the electron beam that has passed through the accelerating electrode in a predetermined direction, and electrons deflected by the deflection electrode. a sampling means for sampling the beam;
and electron detection means for detecting the electron beam sampled by the sampling means, and the accelerating electrode is plate-shaped with an opening.

The second invention is further patented in that a blanking deflection electrode is provided for deflecting the electron beam passing through the deflection electrode in a direction perpendicular to the sweeping direction of the deflection electrode.

[Operation] In the present invention, incident light with a constant repetition frequency is made incident on the photocathode of the sampling streak tube to emit an electron beam, the electron beam from the photocathode is accelerated by an accelerating electrode, and then the electron beam is accelerated at a predetermined rate by a deflection electrode. The waveform of the incident light is observed by sweeping the electron beam in the direction, sampling the swept electron beam with a sampling means, and detecting it with an electron detection means. By the way, when a mesh-like electrode is used as the accelerating electrode, photoelectrons due to scattered light from the accelerating electrode become background noise with a predetermined spread and mix with the signal electrons. For this reason, conventionally, the deflection voltage applied to the deflection electrode has a large amplitude to prevent the sampling means from sampling background noise caused by incident light during a period when no sweeping is performed. However, by increasing the amplitude of the deflection voltage, the distance between the deflection electrodes cannot be narrowed, and there is a limit to improving the deflection sensitivity, and the repetition frequency of deflection cannot be increased. On the other hand, in the present invention, since the accelerating electrode is formed into a plate shape with an opening, the photoelectrons due to scattered light from the accelerating electrode are blocked by the non-opening part of the accelerating electrode, and become background noise and signal. The probability of contamination with electrons is significantly reduced. As a result, even if the deflection voltage applied to the deflection electrode is made to have a small amplitude, the background noise due to the incident light that enters during the period when no sweeping is performed is extremely small, so the probability of sampling background noise by the sampling means is reduced. . Therefore, the deflection voltage applied to the deflection electrodes can be made to have a small amplitude, and accordingly, the spacing between the deflection electrodes can be made small, thereby improving the deflection sensitivity and at the same time increasing the repetition frequency of deflection. .

Further, in the present invention, the blanking deflection electrode provided after the deflection electrode deflects the electron beam that has passed through the deflection electrode in a direction perpendicular to the sweep direction of the deflection electrode. For example, a blanking deflection voltage synchronized with the deflection voltage applied to the deflection electrode is applied to the blanking deflection electrode during the retrace period of the deflection electrode. As a result, during the sweep period of the electron beam by the deflection electrode, the electron beam is sampled by the sampling means, but during the retrace period, the electron beam is moved in a direction perpendicular to the sweep direction of the deflection electrode by the blanking deflection voltage. Since it is deflected to the side, it can be prevented from being sampled by the sampling means.

〔Example〕

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a block diagram of a first embodiment of an optical waveform observation device according to the present invention. In FIG. 1, parts similar to those in FIG. 10 are designated by the same reference numerals, and explanations thereof will be omitted. In the optical waveform observation device of the first embodiment, unlike the conventional streak tube 130 or sampling streak tube 150, the accelerating electrode 2 is not mesh-shaped but is a plate with an opening 3 of a predetermined size approximately in the center. A sampling streak tube 1 having a shape of a shape is used. The opening 3 of the accelerating electrode 2 has a size of about 30 μm×3 mm. Note that the opening 3 may be provided with a mesh, or may not be provided with a mesh. Further, the sampling electrode 4 is a sampling electrode 15 of a conventional sampling streak tube 150 shown in FIG.
Although it has a slit 5 like 1, the sampling electrode 4 is not necessarily connected to the fluorescent surface 134 so as to have the same potential. That is, if desired, a high voltage is applied between the sampling electrode 4 and the fluorescent surface 134 so that the electrons passing through the slit 5 can be accelerated at a later stage and made to enter the fluorescent surface 134.

The light incident on the photocathode 131 of the sampling streak tube 1 is a light pulse having a repetition frequency whose waveform is to be observed.
The beam is outputted by a beam splitter 102, an optical delay means 11, and an input optical system 12.

The beam splitter 102 splits a part of the incident light output from the pulsed light source 10 and makes it enter the photodiode 105 in the same manner as described above. A part of the incident light is photoelectrically converted by the photodiode 105 and becomes an electric trigger signal TR.As mentioned above, this electric trigger signal TR is
The signal is gradually delayed by the time sweep circuit 107, converted into a deflection trigger signal, and applied to the deflection circuit 13.

Note that instead of generating the electric trigger signal TR by photoelectric conversion using the photodiode 105, the switch 14 may be switched to use the drive signal of the pulsed light source 10 as the electric trigger signal TR.

The optical waveform observation device having such a configuration operates in accordance with the time charts shown in FIGS. 11a to 11e, like the conventional optical waveform observation device. However, the first
In the optical waveform observation device of the embodiment, the accelerating electrode 2 of the sampling streak tube is plate-shaped and has an aperture 3 only at approximately the center thereof, so that the scattered light is The photoelectron BG due to DF is blocked by the non-opening part of the accelerating electrode 2,
The deflection electrode 133 and the sampling electrode 4 can be prevented from being directed to each other. As a result, the electron density ρ' of the electron beam reaching the sampling electrode 4 becomes as shown in FIG. 2b. As is clear from comparing FIG. _2b with FIG. By using this, it is possible to effectively block the influence of photoelectrons due to scattered light on the accelerating electrode 2 and reduce background noise.

Therefore, since the sampling streak tube 1 uses the plate-shaped acceleration electrode 2, the deflection electrode 1
There is no need to increase the amplitude of the deflection voltage applied to the optical waveform observation device 33, and the potential V _n 1−V _n of the deflection voltage V in the time chart of FIG. is completed,
For example, they can be set to about +32.5V and -32.5V, respectively. In other words, even if the deflection voltage V is reduced in this way and the electron beam is set to be incident at a position not far from the slit 5 of the sampling electrode 4 during the period when no sweeping is performed, compared to the conventional device, the scattering will occur. Almost no photoelectrons due to light reach the sampling electrode 14, and even if they do, the spread of the density distribution ρ _e ' of photoelectrons of scattered light is small (when the accelerating electrode is shaped like a mesh, the arrival rate of photoelectrons of scattered light is While the arrival rate of regular signal electrons is about 10 ^-3 , in the accelerating electrode 2 of this embodiment, the arrival rate of photoelectrons of scattered light is about 10 ^-6 compared to the arrival rate of regular signal electrons. The probability that the photoelectrons of the scattered light pass through the slit 5 is reduced by the order of 10 ^{-3 from about 10 -3} to about ^{10 -6} , compared to the probability that the signal electrons pass, and the sampling waveform Accurate observation is possible without being affected by background noise.
Furthermore, the amplitude of the deflection voltage V can be made small. Furthermore, even if the linearity of the slope of the deflection voltage waveform during sweeping of the electron beam is no longer ensured, the deflection voltage waveform when passing the electron beam through the slit 5 of the sampling electrode 4, that is, when sampling, will change at each repetition period. If they are the same, the observation accuracy of the sampled waveform to be extracted will not be affected in any way.

In this way, in the optical waveform observation device of the first embodiment, the deflection electrode 1 of the sampling streak tube 1
Since the amplitude of the deflection voltage applied to the deflection electrodes 133 can be made small, even if the distance between the pair of deflection electrodes 133 is considerably reduced, a situation in which the deflected electron beam collides with the deflection electrodes 133 during the non-sweep period can be prevented. However, the deflection sensitivity can be improved by about twice that of the conventional one. This improves the time resolution and reduces the potential V _n to 65V.
It is possible to obtain a time resolution of several picoseconds with a certain amplitude. Note that conventional devices require a voltage of several 100V to several 1000V or more to obtain this level of time resolution. Furthermore, since the amplitude of the deflection voltage can be made small, the deflection circuit 13 can generate a deflection voltage with a high repetition frequency of about _4MHz . That is, in the deflection circuit 108 of the conventional optical waveform observation device, an element such as an avalanche transistor or a triode was used because it was necessary to generate a large amplitude deflection voltage. However, the deflection circuit 108 using such an element was only able to generate a deflection voltage with a slow repetition frequency of about 1 KH _Z at most, so it was difficult to generate a deflection voltage of about 100 _MHz , which is generated by a mode-locked dye laser or a semiconductor laser. It is not possible to efficiently capture high-speed repetitive optical phenomena. In order to compensate for this drawback of slow repetition frequency, if a high-speed, high-voltage, positive and strong wave deflection voltage of about 100 _MHZ is generated by an LC resonant circuit in the deflection circuit 108, it is possible to achieve high-speed repetition synchronized with the high-speed repetition optical phenomenon. Deflection enables efficient measurement, but
Since the LC resonant circuit is used, the repetition frequency of the optical phenomenon is fixed, which limits measurement. Also,
A drawback is that measurement accuracy deteriorates significantly if the repetition frequency or phase of the optical phenomenon to be observed changes during measurement. In this way, with conventional optical waveform observation devices, the deflection voltage had to have a large amplitude, so it was not possible to conveniently generate a deflection voltage with a high repetition frequency. This deflection voltage is especially necessary to perform high-speed sampling to compensate for the reduction in signal utilization efficiency due to the sampling method.

In the first embodiment, since the amplitude of the deflection voltage may be small, the switching element or driving element of the deflection circuit 13 may have a relatively low withstand voltage. By configuring it with a diode or the like, high-speed repetitive deflection of, for example, about 4MH _Z can be easily achieved. Furthermore, 4MH _Z
Although this repetition frequency is lower than the repetition frequency of about _100MHz achieved by an LC resonant circuit, it has many advantages as a general-purpose measuring instrument in that the frequency to be measured is not fixed.

To give a specific example, if the slit width w of the slit 5 of the sampling electrode 4 is 60 μm, and the thickness u of the electron beam is 80 μm, the sweep speed v _t is calculated by equation (1) in order to give an aperture time Δt of 10 picoseconds. According to 10
It must be on the order of mm/nanosecond. In addition, the deflection sensitivity S of sampling streak tube 1 was set to 0.1 mm/V.
Then, the deflection voltage slew rate T required to obtain an aperture time Δt of 10 picoseconds is
is 100 V/nanosecond according to equation (2), and such a slew rate T is a value that can be sufficiently achieved by a deflection circuit composed of high-frequency transistors, step recovery diodes, and the like.

In this manner, according to the first embodiment, by making the accelerating electrode 2 plate-shaped with the opening 3, the amplitude of the deflection voltage can be made small. By narrowing the angle, the deflection sensitivity S can be improved by about twice as much, and at the same time, high-speed repetitive deflection of about 4MH _Z can be realized.

Further, in the first embodiment, various aperture times Δt can be obtained by changing the slope of the deflection voltage waveform being swept in the deflection circuit 13. In the sampling method of this embodiment, high temporal resolution can be obtained by shortening the aperture time Δt, but the time for extracting the sampling waveform becomes correspondingly shorter, and the efficiency of acquiring the sampling waveform decreases. Therefore, when measuring slow light phenomena, a significantly higher time resolution is not required, so the slope of the deflection voltage waveform during sweeping is made gentler, thereby increasing the aperture time Δt and increasing the sampling waveform acquisition efficiency. , with good S/
It can be observed by N ratio. Such means for changing the slope of the deflection voltage waveform can be realized by a Miller integration circuit.

FIG. 3 is a partial configuration diagram of a second embodiment of the optical waveform observation device according to the present invention.

The sampling streak tube 20 of the optical waveform observation device shown in FIG.
A blanking electrode 21 is provided between the sampling electrode 4 and the sampling electrode 4 . This blanking electrode 2
1 is a deflection electrode 13 as shown in detail in FIG.
After the electron beam is swept from R1 to R2 on the sampling electrode 4 during the sweep period according to 3, the electron beam is swept over the deflection electrode 133 so that the electron beam does not pass through the slit 5 of the sampling electrode 4 during the retrace period of the deflection electrode 133. This is for deflecting in a direction perpendicular to the sweep direction. That is, by the blanking deflection voltage applied to the blanking deflection electrode 21, the electron beam can be prevented from passing through the slit 5 by following the trajectory from R3 to R4 on the sampling electrode 4 during the retrace period by the deflection electrode 133. can.

A blanking deflection voltage applied to the blanking deflection electrode 21 is generated by a blanking deflection circuit 22 . The same deflection trigger signal applied to the deflection circuit 13 is applied to the blanking deflection circuit 22 from the time sweep circuit 107.

5a and 5b are time charts of the deflection voltage generated in the deflection circuit 13 and the blanking deflection voltage generated in the blanking deflection circuit 22, respectively. Referring to FIGS. 5a and 5b, it can be seen that the deflection voltage V is
During the sweep period _ts during which the voltage drops from V _n to -V _n , the blanking deflection voltage V _b is maintained at "0" V, and the electron beam swept by the deflection electrode 133 is not subjected to blanking deflection. , as shown in FIG. 4, it forms a trajectory from R1 to R2 on the sampling electrode 4, passes through the slit 5, and is sampled. When the deflection voltage V is -V _n , the electron beam becomes R2 on the sampling electrode 4, but at this time the blanking deflection voltage V _b becomes "0".
When increasing from to +V _k , the electron beam moves from R2 to R3 on the sampling electrode 4. The blanking deflection voltage V _b is defined as the deflection voltage V from −V _n to V _n
It is held at +V _k during the retrace period t _r . As a result, during the retrace period _tr , the electron beam takes a trajectory from R3 to R4 on the sampling electrode 4, does not pass through the slit 5 of the sampling electrode 4, and is not sampled. After the retrace period t _r ends,
The electron beam becomes R4 on the sampling electrode 4, but returns to R1 when the blanking deflection voltage V _b becomes "0" again.

By applying the blanking deflection voltage V _b to the blanking deflection electrode 21 in this manner, it is possible to reduce noise due to incident light during the retrace period t _r and to perform waveform observation with a good S/N ratio.

Note that in this embodiment, the blanking deflection voltage
A trapezoidal waveform synchronized with the deflection voltage V was used as the waveform of V _b so that the electron beam was swept rectangularly on the sampling electrode 4, but the blanking deflection voltage
The waveform of V _b is not limited to the above-mentioned waveform, and may be swept in any manner as long as the electron beam bypasses the slit 5 of the sampling electrode 4 during the retrace period _tr , for example, it may be swept in an elliptical shape. .

Furthermore, as described above, in the sampling streak tubes 1 and 20 of the first and second embodiments, a high voltage of about +5 KV can be applied between the sampling electrode 4 and the fluorescent surface 134, so that the fluorescent surface It is possible to improve the luminous efficiency of the sampling streak tube 134 by about three times compared to the sampling streak tube 150 shown in FIG.

Furthermore, as shown in FIGS. 6a and 6b, microchannel plates 28 and 29 may be provided downstream of the sampling electrode 4 of the sampling streak tubes 1 and 20 of the above-mentioned first and second embodiments, or The sampling electrode can have a structure as shown in FIG.

The sampling electrode 30 shown in FIG. 7 has a structure in which a microchannel plate 31 is shielded from the electron beam except for its central portion 33. 1 and 3, in which the electron beam simply passes through the slit 5, the center portion 33 of the microchannel plate 31
can be further multiplied and passed through the electron beam.

Further, in the above embodiment, the fluorescent surface 134 is used as an electron detector, but instead of the detection surface 134, an electron multiplier, a channeltron, etc. (not shown) are provided, and the sample is sampled by the sampling electrode. The obtained electrons may be directly multiplied. Further, an electron-implanted semiconductor element (not shown) such as a silicon cell may be provided in place of the fluorescent surface 134, and the sampled electrons may be multiplied and detected using an electron multiplication effect. In the above case, the photomultiplier tube 112 becomes unnecessary. Alternatively, a scintillator (not shown) may be used in place of the fluorescent surface 134, and scintillation light emission caused by collisions of sampled electrons may be detected by the photomultiplier tube 112.

Furthermore, in the above embodiment, only one sampling streak tube is used, but by arranging multiple sampling streak tubes as described above and simultaneously deflecting them using the same or independent deflection circuits, multi-channel optical waveforms can be observed simultaneously. It is also possible to do so.

Further, as shown in FIG. 8, the accelerating electrode 41 is provided with a plurality of slits 42 and 43, the sampling electrode 44 is provided with the same number of slits 45 and 46, and each slit 45 and
A multi-channel sampling streak tube 40 provided with the same number of electron multipliers 47 and 48 for multiplying the electrons passing through 46 may be used to simultaneously observe the waveforms of multi-channel incident light. In other words, in the multi-channel optical waveform observation device shown in FIG. An electron beam is emitted. Incident light CHA,
Each electron beam corresponding to CHB passes through the slits 42 and 43 of the accelerating electrode 41, and then passes through the common perforated electrode 137, the deflection electrode 133, and
The signals pass through the blanking deflection electrode 21 and through the respective slits 45 and 46 of the sampling electrode 44, are multiplied by the electron multipliers 47 and 48, and are output, and are subjected to signal processing by the multi-channel signal processing circuit 50.

Further, as shown in FIG. 9, the sampling electrode is a microchannel plate 61 in which a plurality of channels are arranged in a long slit shape in a direction perpendicular to the direction in which the deflection electrode 133 sweeps, and a fluorescent surface 134 is provided immediately after the microchannel plate 61. The light emitted from the fluorescent surface 134 may be guided to the linear image sensor 63 by the fiber plate 62. The linear image sensor 63 can scan and read information on spatially incident light on the photocathode 131 distributed in a direction perpendicular to the sweeping direction of the deflection electrode 133.

Such a configuration is suitable for, for example, making one-dimensional optical information such as a multispectrum separated by the spectroscope 64 incident on the photocathode 131 and observing this one-dimensional optical information with high accuracy.

〔Effect of the invention〕

As explained above, according to the present invention, since the accelerating electrode of the sampling streak tube is made into a plate-shaped one with an opening, it is possible to reduce the amplitude of the deflection voltage applied to the deflection electrode. ,
By narrowing the spacing between the deflection electrodes, it is possible to improve the deflection sensitivity and at the same time increase the deflection repetition frequency, making it possible to accurately observe the waveform of an optical phenomenon with a high-speed repetition period with high temporal resolution.

Furthermore, in the present invention, by providing a blanking deflection electrode, it is possible to prevent the element beam from being sampled during the retrace period of the deflection electrode, thereby further improving observation accuracy.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a first embodiment of the optical waveform observation device according to the present invention, and Fig. 2a illustrates the shielding of photoelectrons by scattered light when the accelerating electrode is plate-shaped with an aperture. Figure 2b is a diagram showing the electron density distribution on the sampling electrode when the accelerating electrode is a plate-shaped one with an aperture, and Figure 3 is a diagram showing the optical waveform observation device according to the present invention. A configuration diagram of the second embodiment, FIG. 4 is a diagram showing the trajectory of the blanking-deflected electron beam on the sampling electrode, and FIG.
Figures a and b are time charts of the deflection voltage and blanking deflection voltage, respectively. Figures 6 a and b are diagrams showing a sampling means in which a microchannel plate is attached to the rear stage of the sampling electrode, respectively. A diagram showing a sampling means provided with a shielding film, FIG. 8 is a configuration diagram of a multi-channel optical waveform observation device, FIG. 9 is a configuration diagram of an optical waveform observation device using a linear image sensor, and FIG. 10 is a configuration diagram of a conventional optical waveform observation device. Figures 11a to 11e are diagrams of the configuration of the optical waveform observation device shown in Figures 11a to 11e, respectively.
The figure shows the configuration of a conventional sampling streak tube.
Figure 13a is a diagram for explaining the shielding of photoelectrons by scattered light when the accelerating electrode is mesh-shaped, and Figure 13b is a diagram for explaining the shielding of photoelectrons by scattered light when the accelerating electrode is mesh-shaped. It is a figure showing electron density distribution. 1,20...sampling streak tube, 2...
...Accelerating electrode, 3...Aperture, 4...Sampling electrode, 5...Slit, 21...Blanking deflection electrode, 131...Photocathode, 133...Deflection electrode,
134...Fluorescent surface.

Claims (1)

[Scope of Claims] 1. In an optical waveform observation device of the type that observes the waveform of incident light having a constant repetition frequency using a sampling streak tube, the sampling streak tube includes a photocathode on which the incident light enters, and a an accelerating electrode that accelerates the emitted electron beam;
A deflection electrode that sweeps the electron beam that has passed through the accelerating electrode in a predetermined direction, a sampling means that samples the electron beam deflected by the deflection electrode, and an electron that detects the electron beam sampled by the sampling means. 1. An optical waveform observation device comprising: a detection means, wherein the accelerating electrode is plate-shaped with an aperture. 2. Claim 1, wherein the opening of the accelerating electrode is approximately 30 μm x 3 mm.
The optical waveform observation device described in . 3. The optical waveform observation device according to claim 1, wherein the sampling means is a sampling electrode provided with an aperture. 4. The optical waveform observation device according to claim 1, wherein the sampling means comprises a sampling electrode provided with an aperture and a microchannel plate provided after the sampling electrode. 5. The optical waveform observation device according to claim 1, wherein the sampling means comprises a microchannel plate configured so that only a predetermined portion thereof passes the electron beam. 6. The optical waveform observation device according to claim 1, wherein the electron detection means is a fluorescent surface. 7. The optical waveform observation device according to claim 1, wherein the electron detection means is an electron multiplier that multiplies the electrons in the sampled electron beam. 8. The optical waveform observation device according to claim 1, wherein the electron detection means is a channel tron. 9. The optical waveform observation device according to claim 1, wherein the electron detection means is an electron implanted semiconductor element. 10. The optical waveform observation device according to claim 1, wherein the electron detection means is a scintillator. 11 The accelerating electrode includes a plurality of apertures, the sampling means includes the same number of sampling parts as the plurality of apertures of the accelerating electrode, and the electron detection means detects the electron beam that has passed through each sampling part of the sampling means. Claim 1 is characterized in that it is equipped with the same number of independent electron multipliers that multiply the number of electrons, and is adapted to simultaneously observe multi-channel incident light incident on the photocathode. Optical waveform observation device. 12 The sampling means is a microchannel plate in which a plurality of channels are arranged in the form of long slits in a direction perpendicular to the direction in which the deflection electrodes are swept, and the electron detection means is a fluorescent plate provided immediately after the microchannel plate. 2. The optical waveform observation device according to claim 1, wherein the fluorescent surface is emitted by a fiber plate and guided to a linear image sensor. 13 In an optical waveform observation device that uses a sampling streak tube to observe the waveform of incident light having a constant repetition frequency, the sampling streak tube has a photocathode on which the incident light enters and an electron beam emitted from the photocathode. An accelerating electrode that accelerates, a deflection electrode that sweeps the electron beam that has passed through the acceleration electrode in a predetermined direction, a blanking deflection electrode that deflects the electron beam that has passed through the deflection electrode in a direction perpendicular to the sweeping direction of the deflection electrode, and a deflection electrode. and a sampling means for sampling the electron beam that has passed through the blanking deflection electrode, and an electron detection means for detecting the electron beam sampled by the sampling means, and the accelerating electrode is a plate-shaped plate having an aperture. An optical waveform observation device characterized by: 14. Claim 13, characterized in that a blanking deflection voltage synchronized with a deflection voltage applied to the deflection electrode is applied to the blanking deflection electrode during the retrace period of the deflection electrode. The optical waveform observation device described.