JPH0511763B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" This invention relates to an optical interference gyrometer that detects various angular velocities.

``Prior Art'' As shown in FIG. 6, in a conventional optical interference gyrometer of this type, light 12 from a light source 11 such as a laser is split into a clockwise light 14 and a counterclockwise light 15 by an optical splitting coupler 13.
These lights 14 and 15 are incident on both ends of an optical path 16 that goes around at least once, and the optical path 1
6 clockwise and counterclockwise, respectively, to the optical path 16.
The output lights 17 and 18 are combined by the distribution coupler 13 and interfered with each other, and are sent to the receiver 21 as interference light 19.
The light is received by the The optical path 16 is composed of, for example, an optical fiber wound in a loop shape a plurality of times. When no angular velocity is applied to the optical path 16 in its circumferential direction, the phase difference between the emitted light beams 17 and 18 is almost zero, but the angular velocity along the circumferential direction of the optical path 16, that is, around the axis of the optical path 16 When the angular velocity Ω is applied, this angular velocity causes a so-called sagnac effect, and the output light 1 propagating through the optical path 16
A phase difference Δφ occurs between 7 and 18. This phase difference △φ is expressed as △φ=4πRL/λCΩ (1). Here, R is the radius of the loop-shaped optical path 16, L is the length of the loop-shaped optical path 16, λ is the wavelength of the light from the light source 11, and C is the speed of the light. Therefore, the light intensity I ₀ of the interference light 19 is I ₀ ∝1+cos△φ (2). By measuring the intensity I ₀ of the interference light 19, the angular velocity Ω can be detected. When the input angular velocity Ω is small, the phase difference Δφ is small, the change in cos Δφ is slight, and the sensitivity becomes extremely low.

In order to optimize the input sensitivity from this point of view, conventionally, as shown in FIG. A method is used in which both the lights 14 and 15, which propagate in opposite directions, are phase-modulated by a drive signal from a drive signal. In this case, interference light 19
The intensity I ₀ is I ₀ =C{1+cos△φ(J ₀ (x)+2J ₂ (x)cos2ωt′+...
+2J ₂ m(x)cos2mωt′+……)+sin△φ(2J ₁ (x)sinω
t′+2J ₃ (x)
sin3ωt′＋……＋2J _2n-1 (x)sin(2m _-1 )ωt′＋……)
}...(3) becomes.

Here, C: constant J _o : n-th Betzel function (n=0, 1, 2, 3
...) x: 2Asinπf ₀ τ A: Modulation index τ: Propagation time of light through optical path 16 ₀ : Driving frequency of phase modulator 22 t': t-τ/2 "Problem to be solved by the invention" As is clear from equation (3), the intensity I ₀ of the interference light 19 includes a term proportional to cosΔφ and a term proportional to sinΔφ. Conventionally, in order to increase the sensitivity in the low input angular velocity range, the output of the photoreceiver 21 is synchronously detected by the modulation signal of the drive signal source 23 in the synchronous detector 24, and the component proportional to sin△φ is detected by the synchronous detector 24.
Only the same component as the drive frequency ₀ of the phase modulator 22 was extracted. For this reason, the input angular velocity Ω increases and the phase difference between the clockwise light 14 and the counterclockwise light 15 is △
When φ approaches π/2, the sensitivity becomes extremely poor,
Dynamite Cleanse was restricted.

On the other hand, the output of the synchronous detection circuit 24 is obtained by multiplying the signal input to the synchronous detection circuit 24 by the reference signal.

The reference signal is used for a switching command of the synchronous detection circuit 24, and its signal form is a rectangular wave. By the way, the Freeier expansion formula for the square wave as a reference signal is ≡ V _R = 4/π (sinωt+1/3sin3ωt+1/5sin
ωt+...) Here, ω=2πf ₀ ...(4).

Here, as shown in FIG. 7, the output of the photodetector 21, that is,
When the photoelectric conversion signal of the interference light expressed by equation (3) is synchronously detected by the modulation signal of the drive signal source 23 in the synchronous detection circuit 24, a DC component and an AC component appear in the output.

The AC component can be removed by subsequently providing a low-pass filter and there is no problem, but the DC component is the result of synchronous detection using odd harmonics of the reference signal, especially the third harmonic, that is, the result of multiplication as shown in equation (3). A DC component of third or higher harmonics among the frequency components appears. The synchronous detection DC output V ₁ of the fundamental frequency component is V ₁ = 4/πK ₁ J ₁ (x)sin△φ ...(5) K ₁ : Constant On the other hand, the synchronous detection DC output V 1 of the 3rd harmonic component ₂ is V ₂ = 4/3πK ₃ J ₃ (x)sin△φ ……(6) K ₃ : Constant Here, in equation (5), the value of x is set so that the value of J ₁ (x) is maximized. For example, if it is set to (1.84), then J ₁ (x)≈0.582 and J ₃ (x)≈0.105, and if K ₁ =K ₂ , V ₂ becomes 6% of V ₁ , which is a size that cannot be ignored.

Furthermore, since J ₁ (x) is at the apex of the Betzel curve, it does not change much even if x changes, but J ₃ (x) is in the middle of the slope of the Betzel curve and responds sensitively to changes in x. Therefore, there is a disadvantage that the output fluctuation becomes large due to the third harmonic component _V2 .

"Means for solving the problem" An optical path that goes around at least once, a means for transmitting clockwise light and counterclockwise light to the optical path, and a means for transmitting clockwise light and counterclockwise light that have propagated through the optical path. An interference means for causing interference, a phase modulator that is arranged in series between the interference means and one end of the optical path to change the phase of the clockwise light and the counterclockwise light, and a phase modulator that changes the optical intensity of the interference light electrically. a photoreceiver for detecting a signal; a means for synchronously detecting an arbitrary odd-numbered wave component synchronized with the optical modulation frequency of the phase modulator in the output from the photoreceiver; means for synchronously detecting an arbitrary even number wave component of a signal synchronized with the signal; a detection output of the odd number wave component synchronous detection means;
a first switching means for switching and outputting the detected output of the even-numbered wave component synchronous detection means; a second switching means for switching and outputting the output of the first switching means and its inverted output; A first detecting means detects when the output of the means becomes larger than a first predetermined value, and a second detecting means detects this when the output of the second switching means becomes smaller than a second predetermined value smaller than the first predetermined value. 2 detecting means and the number of detections for each detection by the first detecting means is cumulatively added, and the second detecting means
A cumulative addition/subtraction means for cumulatively subtracting the number of detections from the cumulative addition value each time the detection means detects the detection means, and the cumulative addition/subtraction value of the cumulative addition/subtraction means is an even number (including 0).
Take out the output of the odd-numbered wave component synchronous detection means at
means for controlling the first switching means to extract the output of the even-numbered wave component synchronous detection means;
If the above cumulative addition/subtraction value is positive, 4n and 4n+1(n
=0, 1, 2...), and if negative, the output of the first switching means is taken out at -(4n+3) and -(4n+4), and the inverted output of the first switching means is taken out at the other points. means for controlling the second switching means;
An optical interference angular velocity meter is constructed by the output of the second switching means and means for outputting the cumulative addition/subtraction value as a detected angular velocity.

According to the configuration of the present invention, the optical interference angular velocity has a wide dynamic range, can be measured with high accuracy and good linearity over the entire range, and can maintain input sensitivity constant over the entire operating temperature range. We can provide a meter.

Further, according to the present invention, it is possible to eliminate the influence of the synchronous detection component of the third harmonic, and to provide an optical interference gyrometer with little output fluctuation.

"Embodiment" FIG. 1 shows an embodiment of the present invention. Components corresponding to those in FIG. 7 are given the same reference numerals. Light receiver 21
The output of is supplied to AC amplifiers 27 and 28. A.C.
The output of the amplifier 27 is converted into a frequency by a mixer 29.
It is mixed with the signal of _L1 , and its output is passed through and amplified by the same component as the frequency R of the reference signal of the synchronous detector 41 by the AC amplifier 33 having the following bandpass characteristics, and then supplied to the synchronous detector 41.

Mixer 30, low pass filter 39, phase detector 37, oscillator 45 and voltage controlled oscillator (hereinafter referred to as
The signal of frequency _L1 obtained by the phase lock loop PLL ₁ composed of VCO) 35 is the sum or difference of the modulation frequency ₀ supplied to the phase modulator 22 and the frequency _R of the oscillator 45. .

In this embodiment, the frequency ₀ + _L1 is removed by the low-pass filter 39 and only the difference frequency ₀ - _L1 is taken out, so the frequency _L1 becomes ₀ - _R .
Therefore, among the photoelectric conversion signals having the frequency components shown in equation (3) that are input to the mixer 29, only the modulation frequency ₀ component is converted by the mixer 29 to the same frequency as the frequency _R , and the band of the frequency _R is The signal is supplied to an AC amplifier 33 having a next frequency bandpass characteristic.

In the signal supplied to the AC amplifier 33 having bandpass characteristics, the frequency _R component mainly passes through, and most of the other frequency components are removed. Therefore, the third harmonic component is removed. Has bandpass characteristics
The output from the AC amplifier 33 is synchronously detected using a reference signal _R in a synchronous detector 41. The component that is synchronously detected at this time is the component with fundamental frequency ₀ among the frequency components shown in equation (3), and as a result, the signal V ₁ from which the alternating current component has been removed by the low-pass filter 43 is
It becomes a signal proportional to sin△φ.

When synchronously detecting a signal having the frequency component expressed by equation (3), using the synchronous detection means described above can remove the DC conversion of the odd-order signal of the reference frequency of the synchronous detector.

In other words, for example, if ₀ = 50KHz and _L1 = 42KHz, ₀ - _L1 = 8KHz. Therefore, the bandpass filter 33 only needs to have a bandpass characteristic with a center frequency of 8KHz. In contrast, the third of ₀
The next harmonic is 150KHz, and the output of the mixer 29 is 118KHz. Therefore, this 118 KHz cannot pass through the bandpass filter 33 and is removed, and is not synchronously detected.

On the other hand, the output of the AC amplifier 28 is based on the same principle as above, and among the frequency components shown in equation (3), the component twice the fundamental frequency ₀ is periodically detected, and the output V ₂ proportional to cos△φ is sent to the terminal 51. appears in The signal V ₁ proportional to sin Δφ and the signal proportional to cos Δφ are switched by the D output from the reversible counter 57 in the switch 46 .

The polarity of the output of the switch 46 is inverted by the output of the 2° weighted terminal of the reversible counter 57 in the switch 48, and then the linearity correction circuit 4
9 and is output to the gyro output terminal 52.

The output of the switch 48 is supplied to the non-inverting input side and the inverting input side of the comparators 53 and 54, and is compared with the reference voltage +V _r -V _r of the reference power supplies 55 and 56, respectively. The outputs of the comparators 53 and 54 are respectively supplied to an up-count terminal UP and a down-count terminal DO of a reversible counter 57, and are up-counted and down-counted, respectively. The output of the output terminal of the reversible counter 57 having a weight of 2° is supplied to the switch 46 as a switching control signal, and the output of the output terminal having a weight of ²¹ is supplied to the switch 48 as a switching control signal. The switches 46 and 48 are each switched to the terminal NC side in an initial state (the switching control signal is logic "0"), and are switched to the terminal NO side when the switching control signal is logic "1". The count value of the reversible counter can be taken out from the terminal 58.
As mentioned above, the output of the terminal 50 is proportional to sin△φ, and changes sin△φ with respect to the phase difference △φ between the clockwise light and the counterclockwise light, as shown by the curve 66 in FIG. 2A. . The output of the terminal 51 is proportional to cos Δφ with respect to the phase difference Δφ, as shown by a curve 67 in FIG. 2A.

If the phase difference △φ is within the range of 0±π/4, the switch 46 is in the state shown in FIG.
The output proportional to sin△φ from 9 is output to the gyro output terminal 52 after linearity correction.

In the comparator 53, when its input, that is, the output of the switch 46 exceeds the reference voltage _Vr , the voltage shown in FIG.
Generates a pulse as shown in . This pulse is added and counted by a reversible counter 57.

On the other hand, when the output of the switch 46 becomes larger than -V _r in the negative direction, the comparator 54 generates a pulse as shown in FIG.
is subtracted and counted. The output of the reversible counter 57 with a weight of 2° changes as shown in FIG. 2D, and the output with a weight of ²¹ changes as shown in FIG. 2E. When the output of the reversible counter 57 with a weight of 2° is at a high level (logic "1"), the switch 46 is switched, and the signal at the terminal 51, that is, the output proportional to cos△φ, is output to the gyro output terminal after linearity correction. 52. Conversely, when the output of the switch 46 becomes larger than the reference voltage -V _r in the negative direction, a pulse is obtained from the comparator 54, and the reversible counter 57 counts down, thereby causing the output with a weight of 2° to become a high level. The switch 46 is activated and the signal at the terminal 51, ie, the output proportional to cos Δφ, is output to the gyro output terminal 52 after linearity correction, as in the previous case.

From the above state, the phase difference △φ further increases as an absolute amount, and the output proportional to cos △φ becomes the reference voltage + V _r
Or, if the absolute value is larger than −V _r , comparator 5
A pulse is obtained from 3 or 54 and the reversible counter 5
7 is added or subtracted, the switch 46 returns to its original state, and an output proportional to the signal at the terminal 50, ie, sin Δφ, is obtained at the gyro output terminal 52 after linearity correction. At the same time, a signal polarity inversion command (switching control signal) is output by the output of the reversible counter 57 with a weight of 2 ^{to 1} so that the output proportional to sin△φ and cos△φ has a positive characteristic with respect to the phase △φ. The switch 48 is turned on. As a result, switch 46
The polarity of the output is inverted. In the above, if the output voltage of the switch 46, which is proportional to sin △φ and cos △φ when the phase difference △φ is π/4, is set to be slightly smaller in absolute value than the reference voltage V _r , the voltage shown in FIG.
A signal 66 proportional to sin△φ and cos△φ shown in
67 can be obtained as a sawtooth output as shown in FIG. 2G. In addition, hysteresis can be provided in the switching of signals proportional to sin △φ and cos △φ, and stable operation can be achieved. In this way, when the phase difference △φ is within the range of approximately ±π/4 with respect to ±mπ, the sin △φ component is extracted as the gyro output, and the phase difference is within the range of approximately ±π/4 with respect to ±(2m+1)π/2. In the range of , the cosΔφ component is extracted as the gyro output, and the output is obtained with the most preferable linearity over the entire range.

From this output, the angular velocity can be determined using the following formula.

Ω=Cλ/4πRL (mπ/2+KV ₀ ), m=0, ±1,
±2...(7) C is the speed of light, λ is the wavelength of the light from the light source 11, R is the radius of the optical path 16, L is the length of the optical path 16, K is the proportionality constant (rad/V), and V ₀ is The voltage m at the gyro output terminal 52 is the difference between the total number of angle addition pulses and the total number of angle subtraction pulses, that is, the count value of the reversible counter 57, which is taken out from the terminal 58.
The polarity of this angular velocity Ω is determined using the output of the most significant bit of the reversible counter 57.

The dynamic range in this embodiment is a range corresponding to approximately ±64π in phase difference Δφ, that is, approximately ±32 wavelengths. This dynamic range can be further expanded by increasing the number of bits of the reversible counter 57.

In the above, each time the output of the switch 48 becomes larger than +V _r , it is cumulatively added to the counter 57, and each time the output of the switch 48 becomes smaller than -V _r , it is cumulatively subtracted from the counter 57. If the cumulative addition/subtraction value, that is, the count value m of the counter 5, is an even number (including 0), the switch 46 takes out the output of the synchronous detector 41, and if it is an odd number, the switch 46 takes out the output of the synchronous detector 42, If the cumulative addition/subtraction value m is positive, the switch 4 is set to 4n and 4n+1 (n=0, 1, 2,...), and when it is negative, it is set to -(4n+3) and -(4n+4).
8 takes out the output of the switch 46, and other than that, the output of the inverting circuit 47 is taken out.

"Modified Embodiment of the Invention, Part 1" Not only the switching of the outputs of the terminals 50 and 51 and the polarity inversion using the logic circuit shown in FIG.
The output proportional to cos△φ is input into the computer, and the second
The positions corresponding to the intersections of curves 66 and 67 in Figure A and +V _r and -V _r are judged as positive or negative, and the output proportional to sin△φ and the output proportional to cos△φ are switched, and the polarity and linearity are determined. It is also possible to optimize it through calculation processing and output it as a gyro output.

Furthermore, there are many other points for switching between the output proportional to sin△φ and the output proportional to cos△φ and for switching the polarity.

Note that the output proportional to sin Δφ can be obtained not only by synchronous detection of the fundamental wave component but also by synchronous detection of any odd-numbered wave component, as is clear from equation (3). Also cos
An output proportional to Δφ can also be similarly obtained by synchronously detecting any even number wave component.

“Modified embodiment of the invention, part 2” The signal received by the light receiver 21 and photoelectrically converted is
Output light varying optical element of light source 11 (light splitting coupler,
Fluctuations in optical loss due to optical paths, phase modulators, etc. (other optical fibers, polarizers, etc. are also used in gyro optical systems)) Fluctuations in insertion loss of light into optical fibers used as optical paths, etc. fluctuate.
As a result, the inner scale factor of the gyro input/output characteristics fluctuates.

For example, you can solve this problem as follows. In other words, the output after synchronous detection proportional to sin△φ is V ₁ , and the output after synchronous detection proportional to cos △φ is V 1 .
When V ₂ is assumed, it can be expressed as V ₁ =K ₁ sin△φ, V ₂ =K ₂ cos△φ (8). Here, K ₁ and K ₂ are proportionality constants. (However, the gain of the amplifier is adjusted so that K ₁ =K ₂ =K.) When V ₁ and V ₂ are squared and added together, the value takes a constant value as shown in the following formula.

V _f =V ² ₁ +V ² ₂ =K ² (sin ² △φ＋cos ² △φ) = K ²
(Constant) ...(9) Therefore, if the output light of the light source, the gain of the receiver, or the output voltage from the receiver 21 is controlled so that the value of V _f is always constant, the scale factor can be kept constant. can be kept.

An example thereof is shown in FIG.

The output of terminal 50 proportional to sin△φ is the output of terminal 6
The output of terminal 51, which is supplied to terminal 8 and is proportional to cosΔφ, is supplied to terminal 69.

The signals supplied to terminals 68 and 69 are connected to the squaring circuit 7.
The two squared signals are added by an adder circuit 72, and the added output is sent to the reference power supply 7 by a differential amplifier 73.
4 and its error signal is amplified.

The amplified error signal is transmitted to the automatic gain adjustment circuit 7.
7 and input to the terminal 75
The amplitude of the output voltage from the AC amplifier 27, which is outputted from the terminal 76 and shown in FIG.
28.

In this series of closed loops, the closed loop operates so that the error signal output from the differential amplifier 73 is always zero, and therefore the input sensitivity is always kept constant.

Furthermore, in addition to the above method, a signal proportional to sin△φ and a signal proportional to cos△φ are input into the computer, and the absolute quantity of the composite vector of V ₁ and V ₂ , that is, K
It is also possible to calculate the amount by which the output voltage V ₁ and V 2 fluctuate from a preset reference value K _r and numerically correct the output fluctuations of the outputs V 1 and V ₂ .

For example, the numerical correction rate r is shall be.

Here, f(p) is a function of p, f(q) is a function of q, and usually
Use f(p)=1 and f(q)=0. By multiplying the gyro output by this numerical correction factor r, the scale factor of the gyro output can always be kept constant.

"Modified embodiment of the invention, Part 3" In the circuit shown in FIG. 1, the synchronous detection circuit 41,
Ideally, the phase difference between the signal input to 42 and the reference signal f _R is zero.

However, the phase difference between the modulation signal applied to the phase modulator 22 and the fundamental frequency of the interference light varies depending on the environmental conditions to which the phase modulator 22 is exposed, particularly the ambient temperature.

Since the phase modulator 22 is manufactured by winding an optical fiber around a cylindrical electrostrictive vibrator, for example, the input/output phase characteristics are inherently likely to change depending on environmental conditions. Furthermore, if the operating point (modulation frequency) is set at the resonance point of the phase modulator 22, it will vary significantly depending on the environmental conditions.

The phase difference also varies due to variations in the phase characteristics of the optical receiver 21 and the constant-variable amplifiers of the electric circuits subsequent thereto. To solve this problem, for example, you can do the following.

That is, the signal input to the synchronous detectors 59 and 60 shown in FIG. 4 (this corresponds to the synchronous detector 41 or 42 shown in _FIG . The reference signal of the detector 60
V _r2 (V _r2 is out of phase with V _r1 by 90°), low pass filters 61 and 62 of the synchronously detected output (this is the low pass filter 43 or 44 shown in Figure 1).
Assuming that _the outputs V _{01 and V 02} after passing _through (corresponding to ωt + θ _f +90°).

V ₀₁ = V _io・V _r1 = K ₀ sin△φcos (θ−θ _f )
……(11) V ₀₂ =V _io /V _r2 =K ₀ sin△φsin(θ−θ _f ) ……(12) Here, ω=2πf _R θ, θ _f : Phase difference K ₀ = 2A/π becomes. Output of low pass filters 61 and 62
The AC component is removed from V ₀₁ and V ₀₂ so that only the DC component appears, and the output thereof is input to the multiplier 65.
As a result, the output V _n =V ₀₁ ×V ₀₂ of the multiplier 65 is (13)
It becomes like the expression.

V _n =V ₀₁ ×V ₀₂ = (K ₀ sin△φ) ² /2sin2 (θ−θ _f
)...(13) That is, the output polarity of the multiplier 65 is independent of the polarity of the input angular velocity, that is, the phase difference Δφ between the left and right lights of the optical path 16, and is equal to the polarity of the phase difference (θ−θ _f ) and 1: 1
It will now be supported.

Therefore, the output of the multiplier 65 is used as the automatic phase adjuster 64.
By controlling θ f and changing θ _f in accordance with the phase difference θ, the phase difference (θ − θ _f ) can always be kept at zero, and as a result,
It is possible to suppress fluctuations in the scale factor of the gyro input and output due to fluctuations in the phase difference θ. Furthermore, the frequency _L1 given to the mixers 29 and 31 shown in FIG.
Similar effects can be obtained by providing a phase adjuster in _{the L2} signal path and applying the output V _n of the multiplier 65 shown in FIG. 4 to the phase adjuster to control the phases of the signals at frequencies _L1 and _L2 . It will be done.

"Modified embodiment of the invention, Part 4" As shown in FIG.
0 → low-pass filters 61, 62 → phase calculation means 67 → VCO 68 → mixer 29 to form a feedback loop, and the output frequency _L1 of the VCO 68 is controlled so that the phase output of the phase calculation means 67 becomes zero. It can also be configured as

In this case, the phase difference θ is also the same as above.
It is possible to suppress fluctuations in the scale factor of dialo input and output due to fluctuations in .

Furthermore, in addition to the methods shown in Figs. 4 and 5, it is also possible to input the above-mentioned V ₀₁ and V ₀₂ into a computer and calculate the absolute amount of the composite vector of V ₀₁ and V ₀₂ . Fluctuations in the output scale factor can be suppressed.

The absolute amount of the composite vector can generally be determined by squaring V ₀₁ and V ₀₂ and then adding the square root of the resulting values.

Although the phase variation treatment for the signal proportional to sin Δ has been described above, the phase variation treatment for the signal proportional to cos Δ can be dealt with in the same way.

"Operations and Effects of the Invention" In the conventional system shown in Fig. 7, as mentioned above, when the phase difference between the clockwise light and the counterclockwise light approaches π/2, the sensitivity becomes extremely poor and the dynamic range is limited. However, according to the present invention, even if the value of m changes in equation (4) shown above, the linearity is the same as when m is 0, as shown in Figure 2 G, The deviation value does not increase in the high range. By providing the linearity correction circuit 49, high linearity can be obtained over the entire measurement range. Further, in this invention, the dynamic range can theoretically be expanded to an unlimited extent. Furthermore, the output light of the light source, the gain of the light receiver, or the output of the light receiver 21 is combined with a signal proportional to cos△φ and sin△
By controlling by a signal proportional to φ,
Input sensitivity can be kept constant over the operating temperature range.

By controlling the phase difference between the signals input to the synchronous detection means 41 and 42 and the reference signal f _R to always be zero, gyro due to fluctuations in the phase characteristics of the input and output of the phase modulator 22 and the electric circuit can be eliminated. Output fluctuations can be suppressed over the operating temperature range.

Further, by adopting a configuration in which the frequency is converted by a mixer, the frequency becomes such that harmonic components do not pass through the subsequent band pass filter. Therefore, harmonic components are not input to the synchronous detector, and the influence of harmonics can be removed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of the optical interference gyrometer according to the present invention, FIG. 2 is a waveform diagram for explaining its operation, and FIGS. FIGS. 6 and 7 are block diagrams showing some modified embodiments, respectively, for explaining a conventional optical interference angular velocity meter. 11...Light source, 13...Optical distribution coupler, 16...
...Optical path, 21... Light receiver, 22... Phase modulator, 23... Modulation signal source, 24, 41, 42, 5
9, 60... Synchronous detector, 25... Frequency divider, 2
6,45,66...oscillator, 27,28...AC
Amplifier, 29, 30, 31, 32...mixer,
33, 34... AC amplifier with bandpass characteristics,
35, 36, 68...VCO, 37, 38...Phase detector, 39, 40, 43, 44, 61, 62
...Low pass filter, 46, 48 ... Switch, 47 ... Inverter, 49 ... Linearity correction circuit, 50, 51, 58, 75, 76, 68, 69
...Terminal, 52...Gyro output terminal, 53,5
4... Comparator, 55, 56, 74... Reference power supply,
57... Reversible counter, 63... Two-phase generator, 6
4... Automatic phase adjuster, 65... Multiplier, 67...
...Phase calculation means, 70, 71... Square circuit, 72
... Addition circuit, 73 ... Differential amplifier, 77 ... Automatic gain adjustment circuit.

Claims (1)

[Scope of Claims] 1. An optical path that goes around at least once; B. Means for passing clockwise light and counterclockwise light to the optical path; and C. Interference between clockwise light and counterclockwise light that have propagated through the optical path. (D) a phase modulator that is arranged in series between the interference means and one end of the optical path to change the phase of the clockwise light and the counterclockwise light; and (E) the interference light. a photoreceiver that detects the intensity as an electrical signal; a second synchronous detection means for synchronously detecting any even number wave component of the signal synchronized with the optical modulation frequency among the outputs of the optical receiver; H a detection output of the odd number wave component synchronous detection means;
a first switching means for switching and outputting the detection output of the even-numbered wave component synchronous detection means; I a second switching means for switching and outputting the output of the first switching means and its inverted output; K, a first detection means for detecting this when the output of the second switching means becomes larger than a first predetermined value; a second detection means for detecting; L; cumulative addition/subtraction means for cumulatively adding up the number of detections each time the first detection means detects; and cumulatively subtracting the number of detections from the cumulative addition value each time the second detection means detects; and M, the first switching so that the output of the odd-numbered wave component synchronous detection means is taken out when the cumulative addition/subtraction value of the cumulative addition/subtraction means is an even number (including 0), and the output of the even-numbered wave component synchronous detection means is taken out at other times. A means for controlling the means, and N If the above cumulative addition/subtraction value is positive, 4n and 4n+
1 (n=0, 1, 2,...), and if negative -
means for controlling the second switching means such that the output of the first switching means is taken out at (4n+3) and -(4n+4), and the inverted output of the first switching means is taken out at the other points; O the second switching means; An optical interference angular velocity meter comprising: means for outputting the output of the means and the cumulative addition/subtraction value as a detected angular velocity. 2. The output of any electrical circuit preceding the first and second synchronous detection means such that the sum of the squares of the output of the first synchronous detection means and the output of the second synchronous detection means is constant. or a means for controlling the amount of light. 3 The output from the first synchronous detection means and the second
2. The optical interference gyrometer according to claim 1, further comprising means for numerically correcting the angular velocity output signal by determining the amount by which the absolute amount of the composite vector with the output from the synchronous detection means fluctuates from a reference value. 4 Approximately relative to the reference signal of the first synchronous detection means
A third synchronous detection means operates with a reference signal having a phase difference of 90°, and an output that has passed through the first synchronous detection means and an output that has passed through the third synchronous detection means are applied to the first synchronous detection means. a reference signal to be
a first control means for controlling the phase difference between the fundamental frequency component of the reference signal among the signals applied as an input to always be zero; a fourth synchronous detection means that operates with a reference signal having a phase difference, and a reference signal that is applied to the second synchronous detection means from an output that has passed through the second synchronous detection means and an output that has passed through the fourth synchronous detection means. and second control means for controlling the phase difference between the fundamental frequency component of the reference signal and the fundamental frequency component of the reference signal among the signals applied as input to be always zero. . 5 Approximately with respect to the reference signal of the first synchronous detection means
a third synchronous detection means that operates with a reference signal having a phase difference of 90 degrees; and a third synchronous detection means that detects the absolute amount of a composite vector of the output from the first synchronous detection means and the output from the third synchronous detection means. 1 detection means, a fourth synchronous detection means that operates with a reference signal having a phase difference of about 90° with respect to the reference signal of the second synchronous detection means, and an output from the second synchronous detection means and the fourth synchronous detection means.
a second detection means for detecting the absolute amount of the composite vector with the output from the synchronous detection means; and a gyro output of the output of the first detection means by outputting the cumulative addition/subtraction value of the cumulative addition/subtraction means as an even number (including 0). 2. The optical interference angular velocity meter according to claim 1, further comprising means for making the cumulative addition/subtraction value of the cumulative addition/subtraction means an odd number and making the output of the second detection means a gyro output.