JPS6018926B2 - Optical signal observation device - Google Patents

Description

[Detailed description of the invention] The present invention relates to a device for observing optical signals.

Optical signals used in optical communications are generally intensity-modulated, but it has been difficult to accurately observe the level and degree of modulation of this light.

Furthermore, to convert optical signals into electricity, PIN is generally used.
A diode, an avalanche photodiode (APD), or the like is used.

However, in these light-receiving elements for detecting light, the current when no light is incident, that is, the dark current, changes depending on various conditions such as temperature, aging, and power supply voltage, and this deteriorates measurement accuracy the most. Generally, the above-mentioned measurement of the light level and modulation degree refers to the measurement on the tube surface of the observation device, and the measurement of the light level is the measurement of the level of the optical signal waveform relative to the level when no light is incident, the so-called 0 level. On the other hand, measuring the degree of modulation of light means measuring the level ratio of the peaks and troughs of the optical signal waveform with respect to the above-mentioned 0 level.

By the way, this 0 level fluctuates due to the drift of the current and the intensifier as described above, and also changes over time.

Along with this, the optical signal waveform naturally changes by the amount of the 0 level fluctuation. The present invention provides an optical signal observation device that eliminates these problems and can accurately measure the level and degree of modulation of light.

Hereinafter, the present invention will be explained in detail with reference to Examples.

FIG. 1 shows an embodiment for explaining the principle of the present invention. 1 is a fiber with a diameter of about 100 mm for guiding optical signals.

2 is the light emitted from fiber 1.

3 is a lens, 4 is a rotating disk, and this disk has a hole 5 for blocking light 2 or allowing it to pass through.

Reference numeral 6 denotes a motor for rotating the rotary disk 4.

Reference numeral 11 denotes a light receiving element consisting of a PIN diode, APD, etc.

10' is an amplification device for amplifying the output of the light receiving element 11.

This is a cathode ray tube for displaying four waveforms, and 41 and 42 are deflection circuits for deflecting the Y axis and x axis of the cathode ray tube 40, respectively.

43 is a Z mouse circuit for applying a signal to the Z axis of the cathode ray tube 40 to perform brightness modulation.

This is a 44-time axis circuit.

45 is an input terminal for applying a synchronization signal to the time axis circuit 44.

7 is a light receiving diode, and 8 is a light receiving diode for receiving the light emitted by the light emitting diode 7. These two face each other with a rotating disk 4 inserted therebetween, and the light 2 emitted from the fiber 1 is connected to a rotating circle with a hole. In synchronization with the blocking and passing of the light by the plate 4, the light emitted by the light receiving diode 7 is also blocked and passed by the rotating disk.

Reference numeral 9 denotes a control circuit that controls the amplifier device 10 and the time base circuit 44.

The output of the light receiving diode 8 is applied to a control circuit 9, and when the light 2 of the fiber 1 is blocked or passed by the rotating disk 4, the control circuit 9 operates and transmits the output to the amplifier 10 and the time axis circuit 44. to be applied. Light receiving element 1
FIG. 2 shows an example of a circuit configuration up to outputting the output from amplifier 1 through amplifier 10, and details of the operation will be described.

Components that are the same as those shown in FIG. 1 are designated by the same numbers in FIG. 2, so their explanation will be omitted.

12 is a bias power supply for the light receiving element.

13 and 31 are resistors, 14 and 20 are differential amplifiers, and input terminals 15 and 16 and 21 and 2 are respectively connected.
2, output terminals 17 and 23 are provided.

30 is a switch, and 32 is a capacitor, which together with the resistor 31 forms a low-pass filter.

24 is an output terminal of the amplifier.

Now, when there is no light 2 incident on the light receiving element 11, the switch 30 is turned on by a control signal from the control circuit 9.

At this time, a loop from the output terminal 23 of the amplifier 20 to the resistor 31, the switch 30, and the input terminal 22 of the amplifier 20 is connected to form a negative loop. Then, the voltage generated in the resistor 13 by the current of the light receiving element 11 and the offset voltage of the amplifier 14 itself are amplified by the amplifier 14 and appear at the output terminal 17 of the amplifier 14.
It is applied to the input terminal 21 of the amplifier 20. Input terminal 21
The voltage applied to the amplifier 20 is amplified by the amplifier 201 along with the offset voltage of the amplifier 20, but the voltage appearing at the output terminal 23 of the amplifier 20 is negatively fed back to the input terminal 22 of the amplifier 20 via the resistor 31 and the switch 30. Ru. The voltage that is negatively fed back to the input terminal 22 of the amplifier 20 is equal to the sum of the voltage applied to the other input terminal 21 of the amplifier 20 and the offset voltage of the amplifier 20, so that the gain of the amplifier 20 is sufficiently large. Then output terminal 2 of amplifier 20
3, almost no output appears. That is, drifts caused by fluctuations in the current of the light receiving element and the offset voltages of the amplifiers 14 and 20 can be eliminated. on the other hand,
While the switch 30 is off, a voltage that cancels out this drift is stored in the capacitor 32, so that the output terminal 24 can obtain a signal without drift.

FIG. 3 shows waveform diagrams of various parts for explaining the operation of the apparatus of the present invention.

For example, a waveform as shown in FIG. 3A can be obtained at the output terminal 24 in FIG.

During the periods TA and TC during which the light passes through the rotating disk 4, waveforms for the periods TA and TC in FIG. 3A are obtained. Then, the period TB during which the light is blocked by the rotating disk 4
During this period, the waveform of the period indicated by TB in FIG. 3, that is, the 0 level is output. On the other hand, the time axis circuit 44 includes an amplifier 10
A part of the output of the control circuit 9 and a part of the output of the control circuit 9 are applied.

The output waveform of the light receiving diode 8 is as shown in FIG. 3, and the output waveform of the control circuit 9 is as shown in FIG. The wooden waveform is the control circuit 9
from the switch 30 of the amplifier 10 and the time axis circuit 44
The second waveform is applied to the time axis circuit 44 from the control circuit 9.
is applied to The waveform shown in FIG. 3E has its H level (high voltage level) set for a period shorter than the period TB, and while the waveform E is at the H level, the switch 30 is in the normal state. The H level in waveform diagram 2 is set to a period shorter than period TA. The waveforms shown in A, 2 and T in FIG. 3 are applied to the time axis circuit 44, and waveform 2 is H
When the level is reached, the time base circuit 44 becomes able to operate on the signal, and when the positive slope of the signal waveform reaches a predetermined level point 5, the time axis circuit 44 operates and reaches the third level.
As shown in Figure C, the level shifts from L level (low level) to H level, and during the H level period, a slanted waveform as shown in Figure 3 is generated, and when this slope waveform reaches a - constant level, it is shown in Figure C. The waveform is inverted to L level and the forehead diagonal signal shown at the mouth also ends. After a predetermined hold-off period, the circuit operates at a predetermined level point 50 on the positive slope of the signal waveform, and is inverted from the L level to the H level as shown in FIG. Repeat the above operation. When the waveform shown in D goes to the L level, the waveform shown in C cannot shift to the H level regardless of the level of the signal waveform, and the mirror oblique waveform shown in the mouth cannot be generated. However, when the waveform shown in the tree goes to H level, for example, the waveform shown in C goes back to H level in the same way as in the normal oscilloscope mode.
level and generates the disturbing waveform shown at the mouth. When the slope waveform shown at the mouth reaches a certain level, the waveform shown at C is inverted to the L level, and the slope signal shown at the mouth also ends. Then, after a predetermined hold-off period, the above-described operation is repeated to generate a diagonal waveform. When the waveform shown in E shifts to the L level, the waveform shown in C cannot be inverted to the H level, and the slope waveform shown in the left does not occur. Then, when the waveform shown in 2 becomes H level, the above operation is repeated again. The output waveform of the amplifier 10 shown in FIG. 3A is applied to the Y-axis of the cathode ray tube 40 through the Y-axis deflection circuit 41.

The output waveform of the time axis circuit 44 shown at the top is applied to the x-axis of the cathode ray tube 40 through the x-axis deflection circuit 42. The waveform shown in C also becomes the output of the time axis circuit 44 and is applied to the Z axis through the Z axis circuit 43 to produce a crane line at H level.
There is no twill line at L level. Therefore, a waveform as shown in FIG. 4 is obtained on the cathode ray tube surface. 51 is a twill line indicating a 0 level, and 52 is a key line indicating a signal waveform.

The mirror slope of the cervical oblique waveform during the period TB shown in Figure 3 is period m.
It is also possible to reverse the slope of the slope waveform between A and A.

Further, this mirror oblique waveform may be approximated by a staircase wave, and when a staircase wave is used, the crane line 51 shown in FIG. 4 becomes a dotted line. The number of oblique waveforms included between periods TA and TB can be arbitrarily selected. In Figure 3, periods TA and TB or T
During the transition period between B and TC, one signal in FIG.
If the period is longer than the level period, a ramp signal may be generated during this transition period as well.

In this case, the area between the box lines 51 and 52 in Figure 4 will shine (
It will look crushed. Although the fiber 1 is used to introduce light in FIG. 1, light propagating through the air may also be introduced.

Further, the shape of the hole 5 in the rotating disk can be changed in any manner depending on the time for blocking or allowing light to pass through. It may allow light to pass most of the time and block it only briefly. In this case, the hole 5 will have a circumferentially elongated shape. Instead of the rotating disk 4, an optical modulator using ultrasonic waves or the like may be used to pass or block light. At that time, the timing of the cutoff can be synchronized with the optical signal, so the light receiving diode and the light receiving diode 8 are not required, and the control circuit 9 can be configured with a simpler circuit than the time axis rotation 44'. In FIG. 2, an amplifier 20
It is also possible to insert an attenuator or an amplifier in the middle of the negative feedback circuit from the output terminal 23 of the amplifier 20 to the input terminal 22 of the amplifier 20 via the resistor 31 and the switch 30.

The parts shown in FIG. 2 can also be connected as shown in FIG. The same numbers are used for the same parts as in FIG. The difference between Fig. 2 and Fig. 5 is that the negative feedback circuit is connected to the amplifier 201.
Rather, it is fed back to the input terminal 16 of the amplifier 14. In addition, the amplifier 14 in FIG. 2 is stable with respect to input/output switching and gain changes, whereas in the case of FIG. 5, the input/output characteristics of the amplifier 14 are changed significantly. It is not possible to switch only the polarity. At that time, unless the input and output polarities of the amplifier 20 are also switched at the same time, positive feedback may occur and oscillation may occur. Another point is that oscillation is likely to occur if the gain of the amplifier 14 is changed significantly. It is also possible to replace the light receiving element 11, resistor 13, and amplifier 14 shown in FIGS. 2 and 5 with the circuit shown in FIG. 6.

The anode side of the light receiving element 11 shown in FIG. 6 may be connected to a bias power source instead of being grounded. Further, the negative feedback circuit portion in FIGS. 2 and 5 may be changed as shown in FIG. 7.

Here, 33 is a resistor, and 34 is a power source that can change the voltage. By changing the voltage of this power supply 34, the value of the 0 level of the waveform shown in FIG. 3A can be changed. That is, DC offset can be performed. A variable voltage power source 34 can also be obtained through a potentiometer connected to a fixed voltage source. Further, the resistor 33 and the power source 34 that can change the voltage can be replaced with a constant current circuit that can change the current value.

Alternatively, the light receiving element 11 and the resistor 13 may be replaced in FIG. 2 to apply an appropriate bias to the input terminal 16 of the amplifier 14. Further, it is also possible to do as shown in FIG.

Description of the same parts as in FIG. 2 will be omitted. 35 is a buffer amplifier, and 36 is a resistor.

The buffer amplifier 35 may operate as either a voltage source or a current source. If a differential amplifier with a large gain and a small amount of drift is used as the amplifier 35, the effect of removing the drift will be even greater due to its comparison action.

Also, one end of the input terminal of the amplifier 35 in FIG. 8 is grounded, but if a variable voltage is applied to this terminal, D
C can be offset. In the simplest example, a source follower may be used.

The circuit of FIG. 8 can also be combined with the circuits of FIGS. 6 and 7. The negative feedback in FIG. 8 can be changed by resistor 13 as shown in
You can also hang it on one end. Figures 8 and 9 to 10
It may be configured as shown in the figure.

37 is an amplifier which connects the output terminal 23 of the amplifier 20 and the switch 3.
0.

If a differential amplifier with a large gain and a small amount of drift is used as the amplifier 37, the effect of removing the drift will be even greater due to its comparison action. One end of the input terminal of the amplifier 37 is grounded, but if a variable voltage is applied to this terminal, DC offset can be achieved. Figures 2 and 5
In the figure, if a differential amplifier with a small amount of large gain drift is inserted in the feedback circuit as described in FIGS. 8 and 10, the effect of eliminating drift will be even greater.

Further, in FIG. 1, when the optical signal is in the form of a pulse, it is often desired to observe the rising portion of the waveform. In such a case, the Y-axis deflection circuit 41 may be provided with a signal delay circuit such as a delay cable. In FIG. 2, if the drifts of the amplifiers 14 and 20 can be substantially ignored, the negative feedback circuits 31, 30, and 32 may be omitted.

The same applies to FIGS. 5 to 10. Figure 3 shows an example of creating the mirror oblique waveform shown at the mouth from the waveform shown at A.
An optical signal input section as shown in FIG. 11 may be used.

Here, 60 and 62 are fibers, a T-branch circuit that divides the six beams into two, and 63 is a circuit for extracting a synchronizing signal, which is composed of a light receiving element and a wideband amplifier. Reference numeral 64 denotes an output terminal for a synchronization signal, which is connected to the input terminal 45 of the time axis circuit 44.

In addition, 8, 2, 3, 4, 5, and 6 are the same as in FIG. 1, so their explanation will be omitted. However, although 1 is a fiber, it must have an appropriate length (for example, 1 fiber) to give sufficient delay to the optical signal.
0-50m). Even if the optical signal is delayed by this long fiber 1, there is almost no loss in the signal of the light 2 obtained from the end of the fiber 1 due to the fiber's broadband property and low loss property. By using the fiber 1 of an appropriate length in this manner, it is possible to observe the optical signal from the rising edge of the waveform. In this case, light propagating through the air may be introduced instead of the fiber 60. The light receiving element used in the synchronization signal extraction circuit 63 does not need to have good linearity, but one with high sensitivity and high speed is suitable. FIG. 12 is a block diagram showing another embodiment of the optical signal observation device of the present invention.

Components having the same functions as those in FIG. 1 are designated by the same reference numerals. 11
53 is a resistor consisting of a PIN photodiode, an avalanche photodiode (APD), etc., for converting the output current from one end of the light receiving element I1 into a voltage, and 53 is a switch (
The terminal of the light receiving element 11 is connected to a bias power supply +B through a switch 53.

15 is an input terminal of the amplifier circuit 10. Now switch 5
3 is on, the light receiving element 11 is
(e.g. PIN photodiode) conducts current and resists 1
produces a voltage across 3.

This voltage is applied to the input terminal 15 of the amplifier circuit 10, amplified, and applied to the Y-axis of the cathode ray tube 40 via the Y-axis deflection circuit 41. That is, the optical signal is converted into electricity and applied to the Y axis of the cathode ray tube. When the switch 53 is off, the light receiving element 11 does not conduct current even if it receives the light 2, so no voltage is generated across the resistor 13. Therefore, the input voltage at the input terminal 15 of the amplifier circuit 10 is 0, and the voltage on the Y axis of the cathode ray tube 40 is also at 0 level (at the amplifier circuit 10 or Y
If the axis deflection circuit 41 applies a DC offset voltage,
voltage). This situation will be explained using the waveform diagram shown in FIG. A is the input terminal 15 of the amplifier circuit 10
This is an example of a waveform in . The switch 53 is on during the period TA, and is off during the period TB.
On the other hand, a portion of the output of the amplifier device 10 and a portion of the output of the control circuit 9 are applied to the time axis circuit 44 . The output waveform from the control circuit 9 that is applied to control the switch 53 is as shown in . During the period TA, the waveform shown in . is at H level (high voltage level).
During this period, the waveform shown in A is applied to the input terminal 15.
In addition, during the period TB, the waveform shown in FIG. 2 which is the output of the control circuit 9 and is applied to the switch 53 is at L level (low voltage level), and during this period, the signal is applied to the input terminal 15 as shown in FIG. It is at level 0. The output of the control circuit 9 is applied to the switch 53 and also to the time axis circuit 44 at the same time. The time axis circuit 44 generates the waveforms shown in 2 and E from the waveforms shown in F. When the waveform shown in 2 reaches the H level, the waveform shown in 2 is inverted from the L level to the H level. When the waveform shown in FIG. 2 becomes H level, the time axis circuit 44 to which a part of the output signal is applied from the amplifier circuit 10 becomes able to operate on that signal, and the positive slope of the signal waveform is After setting the point 501 shown in the figure, the operation moves from the L level to the H level as shown in C, and the forehead diagonal waveform shown at the beginning of the H level period is generated, and around this time the diagonal waveform When the signal reaches a certain level, the waveform shown in C is inverted to L level, and the disturbing signal shown in C also ends. Then, after a predetermined hold-off period, the signal waveform operates at five predetermined level points of the Shoen slope, and as shown in C, it inverts from the L level to the H level, and the slope waveform shown at the top is activated. occurs. The above-mentioned operations are then repeated for a predetermined period of time. Then, the waveform shown in 2 shifts from the H level to the L level. When the waveform shown in FIG. 2 goes to L level, a signal not shown in FIG. , resulting in the waveform shown in . When the output waveform of the control circuit 9 shown in B goes to L level, the switch 53 to which this is applied turns off, and the waveform of the input terminal 15 shown in A goes to 0 level, while the output of the control circuit 9 goes to the time axis circuit. 441 is also applied, and the time axis circuit 44
Now, the waveform shown in the tree is generated by the transition from the H level to the L level of the waveform shown here (transition from the L level to the H level). When the waveform shown in the tree goes to H level, the waveform shown in C also goes to the H level, similar to the self-excited sweep mode in a normal oscilloscope, for example, and generates the oblique waveform shown in the top.

When the diagonal waveform shown at the mouth reaches a certain level, the waveform shown in C is inverted to the L level, and the diagonal waveform shown at the mouth also ends. After a predetermined hold-off period, the waveform shown in C shifts from the L level to the H level, and the above-described operation is repeated to generate a diagonal forehead shape. When the generation of the slope waveform is repeated for a predetermined period, the waveform shown in the tree shifts from the H level to the L level. Then, the waveform shown in C cannot be inverted to the H level, and the nascent waveform shown in C is not generated. When the waveform shown in this tree is inverted from the H level to the L level, the time base circuit 44 generates a signal (not shown) and applies it to the control circuit 9. After a certain period of time after this application,
The control circuit 9 operates, and the waveform shown in (b) changes from the L level to the H level.
Move to level. After that, repeat the above operation. 13th
Figures a and b show other embodiments of the light-receiving element 11, switch 53, and underground vessel 10 in FIG.
is an intensifier, and 54 is a switch.

In the case of FIG. 13a, the switch 53 may be placed on the cathode side of the light receiving element 11. In case b, when the switch 53 is turned on and off, the switch 54 is turned off and on. Furthermore, in the series connection of the switch 53 and the light receiving element 11 in FIG. 12, the switch 53 and the light receiving element 11 may be replaced. Furthermore, as in the case of FIG. 11, the optical signal input section of the embodiment of FIG. 12 may be as shown in FIG. 14. As is clear from the above description, according to the present invention, it is possible to amplify the optical signal by removing the drift caused by the floor current of the light receiving element, and at the same time, it is possible to observe the accurate 0 level, so it is particularly The effect is large when the level of the optical signal is low.

Furthermore, if we assume that the drift caused by the floor current of the light-receiving element is constant from one interruption of light to the light-receiving element to the next interruption, this drift can be removed, so the interval between interruptions of light can be considerably extended. It is possible to do this, and if the interval is narrowed, it has the effect of eliminating drift within a short period of time.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIG. 1 is a block configuration diagram showing an optical signal observation device of the present invention, FIG. 2 is a circuit configuration diagram showing an embodiment of a light receiving element and an amplifying device constituting the Fukurotaka of the present invention, 3 and 4 are waveform diagrams of various parts of the device of the present invention, and FIGS. 5 to 10 are circuit configuration diagrams showing other embodiments of the light-receiving element and amplifier device constituting the device of the present invention,
FIG. 11 is a block diagram showing another embodiment of the optical signal input section, FIG. 12 is a block diagram showing another embodiment of the device of the present invention, and FIGS. FIG. 14 is a circuit diagram showing another embodiment of the light receiving means constituting the device. FIG. 14 is a diagram showing another embodiment of the optical signal input section of the device of the present invention shown in FIG. 1, 60, 62...Fiber, 2...Light, 3...Lens, 4...Rotating disk, 5...Hole, 6
...Motor, 7...Light emitting diode,
8... Light receiving diode, 9... Control circuit, 10... Amplifying device, 11... Light receiving element, 1
2, 34... Power supply, 13, 31, 33, 36...
・Resistance, 14, 20, 35, 37...Amplifier,
15, 16, 21, 22... Input terminal, 17,
23, 24, 64... Output terminal, 30... Switch, 32... Capacitor, 40... Braun tube, 41
...Y-axis deflection circuit, 42...×Mari deflection circuit, 43...Z-axis deflection circuit, 44...
・Time axis circuit, 45... Synchronization signal input terminal, 6
1...T branch circuit, 63... Synchronous signal extraction circuit. Figure 1 Figure 2 Figure 3 Figure 5 Figure 6 Figure 7 Figure 9 Figure 4 Figure 8 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14

Claims (1)

[Scope of Claims] 1. A light receiving means for detecting an optical signal, an optical intermittent means for blocking or passing an optical signal incident on the light receiving means, an amplifying means for amplifying the output of the light receiving means, and a light receiving means for detecting an optical signal. time axis signal generating means for generating a slope signal in synchronization with the optical signal and generating a brightness signal during the period when the optical signal is being generated; 0 by the output signal and the slope signal and luminance signal from the time axis signal generating means.
1. An optical signal observation device comprising: display means for displaying an optical signal waveform including a level. 2. The time-domain signal generating means includes an amplifying means for amplifying the output of the light receiving means by including a negative feedback path via a switch means that opens and closes in response to the operation of the light intermittent means, and the negative feedback path is formed. a storage means for storing the feedback voltage when the negative feedback path is disconnected, and generates a ramp signal in synchronization with the optical signal when the negative feedback path is disconnected, and the negative feedback path is formed. 2. The optical signal observation device according to claim 1, wherein the optical signal observation device generates the tilt signal even when the tilt signal is present, and generates the luminance signal during the period when the tilt signal is generated. 3. The amplifying means includes a first amplifier that inputs, amplifies and outputs the output of the light receiving means, and a negative feedback path via a switch that is turned on and off in response to the operation of the light intermittent means. 3. The optical signal observation apparatus according to claim 2, further comprising a second amplifier which inputs and amplifies the output of the amplifier. 4. The amplification means includes a first amplifier that inputs, amplifies and outputs the output of the light receiving means, a second amplifier that inputs and amplifies the output of the first amplifier, and a second amplifier that inputs and amplifies the output of the first amplifier. Claim 2, characterized in that a negative feedback path is provided between the input terminal and the output terminal of the second amplifier via a switch that is turned on and off in response to the operation of the optical intermittent means. Optical signal observation device as described in section. 5. Claim 3, characterized in that the first amplifier is configured to form a feedback path via a resistance element, input the output from the light receiving means, and output the amplified output.
The optical signal observation device according to items 1 to 4. 6. The optical signal observation device according to claim 3, wherein the output end of the second amplifier is connected to a power source via a resistance element. 7. The amplification means includes a first amplifier that inputs, amplifies and outputs the output of the light receiving means, a second amplifier that inputs and amplifies the output of the first amplifier, and a second amplifier that inputs and amplifies the output of the first amplifier. Between the input terminal and the output terminal of the second amplifier, there is provided a switch that is turned on and off in response to the operation of the optical intermittent means, and a negative feedback path that passes through a third amplifier and a resistive element. An optical signal observation device according to claim 2 characterized by: 8. The negative feedback path includes a third amplifier whose output end is connected to the input end of the first amplifier via a resistance element;
a fourth amplifier whose input terminal is connected to the output terminal of the second amplifier; and the optical intermittent means which is inserted and connected between the output terminal of the fourth amplifier and the input terminal of the third amplifier. 8. The optical signal observation device according to claim 7, further comprising a switch that is turned on and off in accordance with the operation. 9. Claims characterized in that the light intermittent means is constituted by a rotary disk that rotates and is formed of a hole that allows an optical signal to pass through and a base that blocks the optical signal. The optical signal observation device according to items 1 to 8. 10. The optical signal observation device according to claims 1 to 8, wherein the optical intermittent means is constituted by an optical modulator using ultrasonic waves. 11. The optical signal is configured such that one of the optical signals split through a T-branching means that splits the optical signal into two is delayed by an optical delaying means and input to the optical intermittent means, 11. The optical signal observation device according to claim 1, wherein the other optical signal is input to a synchronization signal extraction means and outputted as a synchronization signal.