JPS6019443B2 - 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.

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

However, in these light-receiving elements for detecting light, the current when no light is incident, that is, the floor current, changes depending on various conditions such as temperature, aging, and power supply voltage, and this has been the main cause of deterioration in measurement accuracy. 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 floor current and the amplifier 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 this problem and can accurately measure the level and degree of modulation of light.

The present invention will be explained in detail below with reference to Examples.

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

2 is light emitted from fiber 1.

3 is a lens, 4 is a rotating disk, and this disk has holes 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.

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

44 is a time axis circuit.

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

7 is a light-emitting 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 interposed therebetween, and the light 2 emitted from the fiber 1 is rotated with a hole 5. At the same time as the light emitted by the light emitting diode 7 is blocked or passed by the rotating disk 4, the light emitted by the light emitting diode 7 is also blocked or passed by the rotating disk.

9 is a control circuit that controls the amplifier 10 and the time base circuit 44.

The output of the photodiode 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 base circuit 44. The impression force is 0. 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 11.

I3, 31, 33, 36, 37, and 38 are resistors, 14 is a sampling head, and 15 and 16 are input terminals and output terminals of sampling head 14, respectively. 20
is an AC amplifier including a differential amplifier, 21 and 22 are input terminals of the AC amplifier 20, 23 is a shaping circuit, 24 is an output terminal of the amplifier 10, and 34 is a potentiometer, both ends of which are connected to the positive and negative power supplies. There is.

3 is a switch, 32 is a capacitor, 35 is a buffer amplifier, and 39 is an attenuator.

Here, the sampling head 14, AC amplifier 20, shaping circuit 23, attenuator 39, etc. constitute a sampling circuit 10a of the sampling oscilloscope, and these are known circuits (for example, Japanese Patent Publication No. 51-24866) for observation of high-frequency signals. This is a wideband circuit suitable for

A detailed explanation of this sampling circuit will be omitted. 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, the circuit from the output terminal 24 to the input terminal 15 of the sampling head 14 through the resistor 31, switch 30, buffer amplifier 35, and resistor 36 is connected to form negative feedback. The waveform obtained at the output terminal 24 is a low-frequency similar waveform which is a stepped approximation of the waveform applied to the input terminal 15 of the sampling head 14, and its polarity is in the same phase. The voltage generated in the resistor 13 by the current of the light receiving element 11 (if the value of the resistor 36 is sufficiently larger than the value of the resistor 13, the current flowing through the resistor 36 can be ignored), the sampling circuit, that is, the sampling head 14, and the AC amplifier. 20, the offset voltage of the shaping circuit 23 and the like is amplified and appears at the output terminal 24. Here, to simplify the explanation, consider the case where there is no resistor 33. The voltage appearing at this output terminal 24 is applied to the resistor 31 and the switch 30.
, are applied to the buffer amplifier 35. buffer amplifier 3
5 is a differential amplifier, and the applied voltage is inverted and amplified and fed back to the input terminal 15 of the sampling head 14 through a resistor 36. This feedback causes output terminal 2
4, almost no output appears. That is, it is possible to eliminate drifts caused by fluctuations in the current of the light receiving element and the offset voltage of the sampling circuit. Furthermore, if a differential amplifier with a large gain and a small amount of drift is used as the amplifier 3, the effect of removing the drift will be even greater due to its comparative action. Further, one end of the input terminal of the amplifier 35 in FIG. 2 is grounded, but if a variable voltage is applied to this terminal, DC offset can be achieved. Further, while the switch 30 is off, a voltage that cancels out this drift is stored in the capacitor 32, so that a signal without drift can be obtained at the output terminal 24. Next, resistor 33 and potentiometer 34
I will explain about it.

Current flowing from potentiometer 34 through resistor 33 flows through resistor 31 creating an offset fin pressure at output terminal 24. 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 is obtained at both ends of the resistor 13 in FIG.

During the periods TA and Tc during which the light passes through the rotating disk 4, waveforms of the periods indicated by T^ and Tc in FIG. 3A are obtained. During the period TB in which the light is blocked by the rotating disk 4, the waveform of the period TB in FIG. 3A, that is, the 0 level is output. On the other hand, the time base circuit 44 receives from its synchronization signal input terminal 45 a synchronization signal shown in FIG. 3C that is synchronized with the optical signal.

The output waveform of the light receiving diode 8 is as shown in FIG. 3G, and the output waveform of the control circuit 9 is as shown in FIGS. 3E and 2. The waveform shown in E is applied from the control circuit 9 to the switch 30 of the amplifier 10 and the time axis circuit 44, and the waveform shown in E is applied from the control circuit 9 to the time axis circuit 44.
is applied to The waveform shown in FIG. 3 has its H level (high voltage level) set for a period shorter than the period TB, and the switch 30 is on while the waveform is at the H level. The H level of the waveform diagram is set to a period shorter than the period T^. The time axis circuit 44 is applied with the waveforms shown in C, H, and H in Fig. 3, and when the waveform H in the waveform diagram becomes H level, the time axis circuit 44 becomes able to operate in response to the synchronization signal C, and the waveform shown in C is applied. It operates in synchronization with the same signal as shown, and generates a slanted waveform as shown by the solid line at the mouth.

The time axis circuit 44 includes a circuit that generates a staircase wave as shown by the dotted line at the mouth, and compares the levels of this staircase wave and the slope waveform, and generates a pulse at the point where they match. That is, the sampling command pulse shown here is generated at the intersection of the steep wave and the staircase wave shown at the mouth. This command pulse is
The signal is applied to the 0 shaping circuit 23, and at the same time, it is made into a very narrow pulse and is applied to the sampling head 14 as a sampling pulse to perform sampling. The sampled point is shown as point 50 in FIG. 3A. When this sampling is performed, the staircase wave advances one step as shown by the dotted line at the mouth, and the mirror oblique waveform also ends. After a certain hold-off period has elapsed, the circuit again responds to the synchronization signal shown in C to generate the oblique waveform shown in C, and repeats the above-described operation. In this way, a low frequency waveform similar to the stepwise changing signal waveform having the amplitude of many points 50 shown in FIG. 3A is obtained at the output terminal 24.

When the waveform shown in the tree of FIG. 3 reaches the L level (low voltage level), the post-slant waveform is not generated regardless of the application of the synchronization signal shown in C, and the staircase wave is reset. In period TB,
When the waveform shown in Fig. 3 becomes H level, the sampling command pulse shown in 2 is generated in the same manner as in the self-excited scan mode in a sampling oscilloscope, and the 0 level is sampled as shown at point 61 in Fig. 3. .

As a result, a 0 level is output to the output terminal 24 of the amplifier 10. Then, the staircase wave shown at the mouth advances. When the waveform shown in 2 becomes L level, the staircase wave is reset. During the period from this reset to the generation of the next staircase wave, the time axis circuit 44 sends out a luminance signal (not shown), and the Z axis circuit 4
3 to the Z-wave of the cathode ray tube 40 so that no twill lines are generated. When the waveform of the tree in FIG. 3 shifts to H level again, the above-mentioned operation is repeated.

A staircase wave indicated by a dotted line at the top of FIG. 3 is outputted from the time axis circuit 44 and applied to the X axis of the cathode ray tube 40 via the x rut deflection circuit 42.

The step-like waveform having the levels of a large number of points 50 and 51 shown in FIG.
1 to the Y axis of the cathode ray tube 40. During periods other than the period when the staircase wave is set as shown in FIG. applied to the axis to apply brightness modulation. As a result, a waveform is obtained on the screen of the cathode ray tube 40, as shown in FIG. 4, represented by a thin dot 52 and a bright dot 53 corresponding to the dots 50 and 51 in FIG. 3A. In the example shown in FIG. 3, no disturbing signal is generated while the waveform shown at H level is at H level during period T8. Even while the indicated waveform is at H level, a sloped waveform may be generated and compared with a staircase wave to generate a sampling command pulse. In Fig. 3, we have explained the case where an external synchronization signal synchronized with the optical signal is used, but it is also possible to obtain the waveform of the optical signal shown in Fig. 3A from both ends of the resistor 13 in Fig. 2 and amplify it with a wideband amplifier. may be obtained by

Alternatively, an optical signal input section as shown in FIG. 5 may be used. Here, 60 and 62 are fibers, 61 is a T-branch circuit that divides light into two, and 63 is a synchronization signal extraction circuit, which is comprised of a light receiving element and a broadband amplifier. Reference numeral 64 denotes an output terminal for a synchronization signal, which is connected to the input terminal 46 of the time base circuit 44.

In addition, 1, 2, 3, 4, 5, and 6 are the same as those 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 to 50). Even if the optical signal is delayed by this long fiber, the light 2 obtained from the end of the fiber 1 has almost no loss of information due to the fiber's broadband properties and low loss properties. In this way, fiber 1 of an appropriate length
By using , it is possible to observe from the rising edge of the optical signal 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. 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 long shape in the circumferential direction. 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 emitting diode 7 and the light receiving diode 8 are no longer necessary, and the control circuit 9 and the time axis circuit 44 can be constructed with simpler circuits. The part shown in Figure 2 is the 6th
It is also possible to connect as shown in FIG. 7 and FIG. The same numbers are used for the same parts as in FIG. However, although 12' in FIG. 7 is a bias power supply, one end thereof is not grounded. In FIG. 2, the resistor 38 and potentiometer 34 are replaced with a constant current source whose current value can be varied, and a DC offset (the value of the 0 level of the waveform shown in FIG. 3A) is changed.

) can also be applied to its output terminal 24. Figure 6,
It may be arranged as shown in FIGS. 7 and 8.

37 is an amplifier connected between the output terminal 24 of the amplifier 20 and the switch 30.

If a differential amplifier with a large gain and little drift is used as the amplifier 37, the effect of removing 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. In Fig. 1, if the optical signal is in the form of a pulse and you want to observe from the rising edge of the waveform, connect the light receiving element 11 and the amplifier 10 with a coaxial cable of an appropriate length (10 m to 50 cm). The signal may be delayed by this.

In FIG. 2, the switch 30, capacitor 32, buffer amplifier 35, and resistor 36 may be omitted if the drift of the sampling circuit including the sampling head 14 etc. can be ignored. FIG. 9 is a block diagram showing another embodiment of the optical signal observation device of the present invention. Here the first
Components with the same functions as those in the figure are designated by the same reference numerals. 11 is a PIN photodiode, an avalanche photodiode (APD)
), 13 is a resistor for converting the output current from one end of the light receiving element 11 into voltage, 53 is a switch (light receiving switch), and the other end of the light receiving element 11 is biased through the switch 53. Connected to power supply +B.

15 is an input terminal of the amplifier circuit 10.

10 is a circuit configuration diagram showing another embodiment of the light receiving element 11 and the amplifying device 10 that constitute the device of the present invention shown in FIG. 10. FIG.

When the switch 53 is turned off and the switch 30 is turned on by the control signal from the control circuit 9, the circuit from the output terminal 24 to the input terminal 15 of the sampling head 14 through the resistor 31, switch 30, buffer amplifier 35, and resistor 36 is as follows. Connected to form negative feedback.

When the switch 53 is turned on and the switch 30 is turned off by a control signal from the control circuit 9, the output terminal 24
The waveform obtained is the input terminal 1 of the sampling head 14.
This is a low frequency similar waveform which is a stepped approximation of the waveform applied to 5, and its polarity is in the same phase. Fluctuations (drift) in the offset voltage of the sampling circuit, that is, the sampling head 14, the AC amplifier 20, the shaping circuit 23, etc., are amplified and appear at the output terminal 24. Here, to simplify the explanation, consider a case where the resistor 33 is not provided. The voltage appearing at this output terminal is applied to resistor 31, switch 30, and buffer amplifier 35. The buffer amplifier 35 is a differential amplifier, and the applied voltage is compared with the voltage (zero) at the other grounded input terminal of this differential amplifier, inverted and amplified, and then sent to the input terminal 15 of the sampling head 14 through a resistor 36. will be given negative feedback. (However, when the switch 53 is off and the switch 30 is on) Due to this feedback, almost no output (drift) appears at the output power terminal 24. That is, drift caused by variations in the offset voltage of the sampling circuit can be eliminated. Amplifier 3
If a differential amplifier with a large gain and low drift is used as the filter 5, the effect of removing drift will be even greater due to its comparison action. One end of the input terminal of the amplifier 35 in FIG. 10 is grounded, but if a variable voltage is applied to this terminal, DC offset can be achieved. While the switch 30 is off, a voltage that cancels the drift is stored in the capacitor 32, so that a signal without drift can be obtained at the output terminal 24. Next, the resistor 33 and potentiometer 34 will be explained.

Operation will now be described with reference to FIG. 3, in which current flowing from potentiometer 34 through resistor 33 flows through resistor 31 and produces an offset voltage at output terminal 24.

For example, a waveform as shown in FIG. 3A is obtained at both ends of the resistor 13.

When the switch 53 is on, waveforms for periods indicated by T^ and Tc are obtained. When the switch 53 is off, a waveform of a period indicated by TB, that is, a 0 level is output. On the other hand, the time base circuit 44 receives from its synchronization signal input terminal 45 a synchronization signal shown in FIG. 3C that is synchronized with the optical signal. The waveforms applied from the control circuit 9 to the switch 53 and the time axis circuit 44 are as shown in the figure.

The time axis circuit 44 to which the waveforms shown in (a) and (b) are applied internally generates waveforms shown in (a) and (b). The waveform shown in 2 has its H level (high voltage level) set in a period shorter than period TB. The H level of the waveform diagram is set to a period shorter than the period T^. When the waveform shown in FIG. 1 shifts from the L level (low voltage level) to the H level and becomes sufficiently stable, the tree shifts from the L level to the H level. When the tree reaches the H level, the time axis circuit 44 becomes operable in response to the synchronization signal C, operates in synchronization with the synchronization signal shown in C, and generates a diagonal waveform shown by the solid line. Time axis circuit 4
4 includes a circuit that generates a staircase wave as shown by the dotted line at the mouth, compares the levels of this staircase wave and the slope waveform, and generates a pulse at the point where they match. That is, the sampling command pulse shown in 2 is generated at the intersection of the slope waveform shown at the mouth and the staircase waveform. This command pulse is applied to the shaping circuit 23 of the amplifier 10, and at the same time, it is made into a very wide pulse and is applied to the sampling head 14 as a sampling pulse to perform sampling. The sampled points are represented by points 50 shown in FIG. When this sampling is performed, the staircase waveform progresses one step as shown by the dotted line at the mouth, and the slope waveform also ends. After a certain hold-off period has elapsed, the slope waveform shown in Figure 3 is generated again in response to the synchronization signal shown in Figure 3A, and the above operation is repeated. A low-frequency waveform similar to a signal waveform that changes in a stepwise manner with The staircase wave will be reset.

During period TB, when the waveform shown in FIG. 3 becomes H level, the sampling command pulse shown in 2 is generated in the same manner as in the self-excited scan mode in a sampling oscilloscope, and the waveform shown in FIG. to sample.

As a result, a 0 level is output to the output terminal 24 of the amplifier 10. Then, proceed in a step-like manner as shown by the dotted springs in the mouth. When the waveform shown in 2 becomes L level, the staircase wave is reset. During the period from this reset to the generation of the next staircase wave, the time axis circuit 44 sends out a brightness modulation signal (not shown),
The voltage is applied to the Z-axis of the cathode ray tube 40 via the Z-axis circuit 43, so that no rope line is generated. When the waveform shown in FIG. 3E changes to H level again, the above-described operation is repeated.

The staircase waveform shown by the dotted line at the top of FIG.
applied to the axis.

A staircase wave having the levels of a large number of points 50 and 51 shown in FIG. During the reset period of the staircase waveform shown by the dotted line and the period other than the base period where the staircase wave is not generated, a pulse waveform (not shown) is generated by the time axis circuit 44 and transmitted to the Z axis of the cathode ray tube 40 via the Z axis circuit 43. applied to the axis to apply brightness modulation. As a result, a waveform is obtained on the screen of the cathode ray tube 40, as shown in FIG. 4, represented by bright spots 52 and 53 corresponding to points 50 and 51 in FIG. 3A. The fact that a gentle slope waveform or the like can be used instead of the staircase wave shown by the dotted line at the beginning of FIG. 3 is the same as in a general sampling oscilloscope. Furthermore, in the opening of FIG. 3, the staircase waveform between the periods TB is upward to the right, but it may be a staircase waveform that is downward to the right from the peak value of the last staircase wave in the period T^. In the example shown at the beginning of Figure 3, the waveform shown in 2 does not generate an H level dark slope signal during the period TB, but the waveform shown in 2 does not generate an H level dark slope signal.
A ramp waveform may also be generated between levels and compared with the staircase waveform to generate a sampling command pulse. Third
In the figure, we have explained the case where an external synchronization signal synchronized with the optical signal is used, but it can be obtained by obtaining the waveform of the optical signal shown in Figure 3A from both ends of the resistor 13 in Figure 10 and amplifying it with a wideband amplifier. It's okay.

Alternatively, an optical signal input section as shown in FIG. 11 may be used.
The parts shown in FIG. 10 can also be connected as shown in FIGS. 12 and 13.

The same numbers are used for the same parts as in FIG. Here, 12 in FIG. 13 is a bias power source. FIGS. 12 and 13 may be replaced with those shown in FIG. 8.

In Fig. 9, when the optical signal is in the form of a pulse, if you want to observe from the rising part of the waveform, connect the light receiving element 11 and the amplifier 10 with a coaxial cable of an appropriate length (10 to 50). You may. 10, 12, and 13, if the drift of the sampling circuit including the sampling head 14 etc. can be ignored, the switch 30, capacitor 32, buffer amplifier 35, amplifier 3
7. The negative feedback path provided by the resistor 36 may be omitted. The part shown in FIG. 10 may be further made as shown in FIG. 14. Here, 54 is a switch, and the other numbers are the same as in FIG. When the switch 53 is turned on and off, the switch 54 is turned on.
is off and on. In addition, in the series connection of the switch 53 and the light receiving element 11 in FIG. 9, the switch 53 and the light receiving element 1
1 may be replaced.

As is clear from the above description, according to the present invention, it is possible to sample an optical signal by removing drift caused by the floor current of the photodetector, and at the same time, it is possible to observe an accurate 0 level. The effect is large when the level of the optical signal is low.

Also, if it is assumed that the drift caused by the current on the light receiving element is constant between the time when light is cut off to the light receiving element and the next time it is cut off, then
This drift can be removed, and it is not possible to significantly lengthen the interval at which the light is interrupted, and if the interval is made narrower, drift within a short period of time can also be eliminated.

[Brief explanation of 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 that constitute the device of the present invention, and FIGS. 3 and 4 are Waveform diagrams of various parts of the device of the present invention, FIG. 5 is a configuration diagram showing another embodiment of the optical signal input section, and FIGS. 6 to 8 are other embodiments of the light receiving element and amplifier that constitute the device of the present invention. Circuit diagram showing the 9th
FIG. 10 is a block diagram showing another embodiment of the optical signal observation device of the present invention, FIG. A configuration diagram showing another embodiment of the optical signal input section of FIG. 9, 12th
1 to 14 are circuit configuration diagrams showing other embodiments of the light receiving element and amplifier shown in FIG. 9. 1,60,62...Fiber, 2...Light, 3... ... Lens, 4 ... Rotating disc, 5 ... Hole, 6
...Motor, 7...Light emitting diode, 8.
...... Light receiving diode, 9... Control circuit, 10...
...Amplification device, 10a ... Sampling circuit, 11 ... Light receiving element, 12 ... Power supply, 1
3, 31, 33, 36, 37, 38... Resistance,
14... Sampling head, 15, 21, 2
2... Input terminal, 16, 24... Output terminal, 20... AC amplifier, 23... Shaping circuit, 30... Switch, 32... Capacitor, 34・
...Potentiometer, 35...Buffer amplifier, 39...Attenuator, 40...
Braun tube, 41... Y-axis deflection circuit, 42...
...X-axis deflection circuit, 43...Z-axis deflection circuit, 44...time axis circuit, 45...synchronous signal input terminal, 61...T Branch circuit, 63...
...Synchronization signal extraction circuit. 1 figure is 4 boxes,

Claims (1)

[Scope of Claims] 1. A light receiving means for detecting an optical signal, a light intermittent means for blocking or passing an optical signal incident on the light receiving means, and an output of the light receiving means when the optical signal is incident. 0 when the low frequency signal and optical signal similar to are blocked.
a sampling circuit and time axis signal generation means for obtaining the level signal by sampling, and a display means for displaying the low frequency signal and the 0 level signal;
An optical signal observation device characterized by displaying an optical signal waveform including a level. 2. An amplifying means provided with a negative feedback path via a switch means that opens and closes in response to the operation of the optical intermittent means, and the negative feedback path is formed between the output end and the input end of the sampling circuit. 2. The optical signal observation device according to claim 1, further comprising a storage means for storing the feedback voltage of the optical signal. 3. The negative feedback path includes a first amplifier whose output end is connected to the input end of the sampling circuit via a resistive element, and a second amplifier whose input end is connected to the output end of the sampling circuit. and a first switch that is inserted and connected between the output terminal of the second amplifier and the input terminal of the first amplifier and turns on and off with respect to the operation of the optical disconnection means. An optical signal observation device according to claim 2 characterized by: 4. The time axis signal generating means generates sampling command pulses at slightly different phases of the optical signals that arrive sequentially, generates the sampling command pulses even when the optical signals are cut off, and generates the sampling command pulses when the optical signals are incident. generating a staircase wave in response to a sampling command pulse to reset the optical signal; and generating a staircase wave in response to a sampling command pulse to reset the optical signal even when the optical signal is cut off;
Furthermore, the sampling circuit is configured to generate a brightness modulation signal for a period from reset to generation of the next staircase wave, and the sampling circuit samples the output of the light receiving means using a sampling command pulse applied from the time axis signal generating means. and configured to output a low frequency signal similar to the optical signal when the optical signal is incident, and to output a 0 level signal when the optical signal is blocked, A similar low frequency signal and a 0 level signal are applied to the Y axis of the display means, a staircase wave is applied to the X axis, and a brightness modulation signal is applied to the Z axis.
An optical signal observation device according to any one of claims 1 to 3, characterized in that an optical signal waveform including a level is displayed. 5. 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 4. 6. Claim 1, wherein the light intermittent means is constituted by an optical modulator using ultrasonic waves.
The optical signal observation device according to items 1 to 4. 7. Claims 1 to 4, characterized in that the light intermittent means is connected in series with the light receiving means.
Optical signal observation device as described in section. 8. The light intermittent means comprises a second switch provided between the light intermittent means and the input end of the amplification means, and a third switch provided between the input end of the amplification means and the ground air. An optical signal observation device according to any one of claims 1 to 4, characterized in that: 9. The light receiving means is connected in series with the light intermittent means and provided in the negative feedback path of the sampling circuit, and the light receiving means is connected in parallel with bias means in which a resistive element and a bias power source are connected in series. An optical signal observation device according to any one of claims 1 to 8, characterized in that: 10 The optical signal is configured such that one of the optical signals split through a T-branching means that divides the optical signal into two is delayed by an optical delaying means and input to the light receiving means, and the other optical signal is 10. The optical signal observation device according to claim 1, wherein the optical signal is input to a synchronization signal extraction means and outputted as a synchronization signal.