CN100349334C - Apparatus and method for controlling ring laser optical cavity length - Google Patents

Abstract

The present invention discloses a device and a method for controlling the length of ring laser optical cavities. The device is mainly composed of a heat-insulated container, a heat-insulated elastic membrane and piezoelectric ceramics, wherein the heat-insulated elastic membrane is tightly fixed on the heat-insulated container (1), and both ends of the piezoelectric ceramics (3) are respectively connected with the heat-insulated elastic membrane and the heat-insulated container. The method has the procedures: the device is connected with a ring laser; dry air is filled in a capillary pipe of the ring laser; the refractive index of the dry air is changed by changing applied voltage on the piezoelectric ceramics; the compensation (delta L compensation) of the length of an optical cavity of the ring laser is changed by changing the refractive index of the dry air; the magnitude of the compensation is approached to the variation quantity (delta L outside) of the length of the optical cavity of the ring laser caused by the external environment; the length of the optical cavity if the ring laser is controlled. The device of the present invention has the advantages of high response speed, high sensitivity, low power consumption, etc., and can be used for mirror type ring lasers, total reflection prism type ring lasers and frequency stabilized systems in straight cavity lasers.

Description

Control the long device and method of annular laser optical cavity

Technical field

The present invention relates to laser technology field, specifically a kind of refractive index of utilizing piezoelectric ceramic electric control ring laser capillary inner drying air, realize the long method of the annular laser optical cavity of control, be mainly used in the frequency stabilization system of reflection mirror ring laser, total reflection type prism ring laser, also can be applied in the straight cavity laser frequency stabilization system.

Background technology

Inertial technology is the general designation of technology such as inertial sensor, stable inertia, inertial navigation, inertial guidance and inertia measurement, is one and relates to multi-disciplinary new and high technology.Gyroscope is the Primary Component of inertial technology, the angular movement that it can responsive single shaft object relative inertness space.The kind of gyro is a lot, mainly contains liquid floated gyroscope, flexible gyroscope, electrostatic gyroscope, laser gyro, optic fiber gyroscope etc.At present, the flexible gyroscopes that use in the inertial navigation system with high speed rotor more.Yet, because high speed rotor is easy to generate the mass unbalance problem, be subjected to the influence of acceleration easily, and need one period warm-up time, therefore, flexible gyroscope itself exists the defective that is difficult to overcome, and can not satisfy the higher requirement of inertia measurement.In contrast to this,, become and onlyly in the inertial technology field obtained practical application because laser gyro is the solid-state gyro that does not need high speed rotor, and fruitful non-electromechanical high-precision inertia sensing instrument.

The quantum optices instrument that laser gyro is is core with two-way travelling-wave annular laser, the oscillation frequency rate variance in the dependence ring laser between two-way capable ripple is measured the angular speed of carrier.The structure of laser gyro comprises: parts such as ring laser, offset frequency assembly, optical cavity length control assembly, signal processing system.The resonant cavity of ring laser usually by three or the four sides high-quality high reflectivity mirror constitute.Gain media gas under the excitation of power supply, along resonant cavity produce the direction of propagation opposite, be clockwise and anticlockwise two-beam.Light frequency is by the optical cavity length decision of resonant cavity in the ring laser.When the resonant cavity transfixion, the frequency of the two-beam that both forward and reverse directions is propagated equates; When resonant cavity has rotational angular velocity, the frequency difference of the two-beam that both forward and reverse directions is propagated, its difference on the frequency is directly proportional with the angular speed of carrier, satisfies following relational expression:

$\mathrm{\&Delta;v}=\frac{4A}{\mathrm{\&lambda;}<L>}\mathrm{\&Omega;}---\left(1\right)$

Wherein, A is an area that annular light path is enclosed,＜L〉be the optical cavity length of resonant cavity, λ is the operation wavelength of ring laser, and Ω is a rotating speed to be measured, and Δ v is the frequency difference of forward and reverse capable ripple.Therefore,, can determine the rotating speed Ω of carrier, the operation principle of Here it is laser gyro if known the frequency difference Δ v of forward and reverse capable ripple.

By (1) formula as seen, the precision that laser gyro is measured rotating speed depends on its certainty of measurement to output frequency difference Δ v, and the stability of ring laser frequency of oscillation v directly influences the certainty of measurement of Δ v.Therefore, high-precision laser gyro all requires the output of ring laser single-frequency, and frequency stabilization.In the ring laser of single-frequency operation, laser frequency v is mainly by the optical cavity length＜L of resonant cavity〉decision, satisfy relational expression

$v=q\frac{C}{<L>}---\left(2\right)$

In the formula, q is a constant, and C is the light velocity in the vacuum.In the real work of laser gyro, external environment causes the optical cavity length changes delta L of ring laser through regular meeting _OutwardThereby, reduced the stability of ring laser frequency of oscillation v.Therefore, for making the ring laser steady operation, must take the frequency stabilization measure.Usually, utilize the optical cavity length changes delta L of frequency stabilization system control ring laser _Mend, and this variation is satisfied

Δ L _Mend≈-Δ L _Outward

Can compensate the variation that causes the ring laser optical cavity length because of external environment, improve the frequency stability of ring laser.

Definition＜L according to optical length 〉=nL, have

$\frac{d<L>}{<L>}=\frac{\mathrm{dL}}{L}+\frac{\mathrm{dn}}{n}---\left(3\right)$

Wherein, n is the refractive index of light path medium, and L is the geometrical length of light path.As seen, control optical cavity length method can have two classes, promptly controls the method for resonant cavity geometrical length L and the method for control light path medium refractive index n.

The frequency stabilization system of ring laser is made up of control optical cavity length device and frequency stabilization servo circuit usually.In the present ring laser frequency stabilization system, mainly contain the device of two kinds of control optical cavity lengths, a kind of is by adopting the speculum of piezoelectric element driving resonant cavity, controlling the geometrical length of resonant cavity, as shown in Figure 1.Piezoelectric ceramic PZT in this device ₁Order about cavity mirror sheet M and produce translation, thereby change the light path of laser, realize the long purpose of the annular laser optical cavity of control, piezoelectric ceramic PZT ₂Make eyeglass M produce small shake, ring laser chamber progress row is modulated.Another kind is by the medium refraction index n in the heater strip temperature control light path, as shown in Figure 2.This device mainly is made up of air chamber and electrical heating wire, is filled with control gaseous in the capillary B of air chamber and ring laser, changes the temperature of control gaseous by heater strip, thereby changes the refractive index of control gaseous, realizes the long purpose of the annular laser optical cavity of control.

China's inertial technology journal, 1994,2 (4): the Ma Younian that 50-57 delivers, the article of Yuan Xiaodong " frequency stabilization system of laser gyro LG " and interrelated data are pointed out, described first kind of long device of the annular laser optical cavity of control is mainly used in reflecting in the frequency stabilization system of mirror ring laser, it has simple in structure, highly sensitive and advantage such as response speed is very fast, but, can have a strong impact on the performance and the measuring precision of laser gyro of ring laser because there is the flexural deformation phenomenon in piezoelectric element in its telescopic process; Described second kind of long device of the annular laser optical cavity of control is mainly used in the frequency stabilization system of total reflection type prism ring laser, it is in the optical cavity length control procedure, do not change the light path of ring laser, control method is simple, can solve the problem that the total reflection type prism ring laser is difficult to realize controlling the resonant cavity geometrical length, but there is following shortcoming, influences its application in high-precision laser gyroscope:

(1) device and the laser of control optical cavity length exist temperature gradient, seriously influence the performance and the measuring precision of laser gyro of ring laser;

(2) adjustment time length, toggle speed and the response speed of control optical cavity length device are low;

(3) power consumption is big.

The content of invention

The objective of the invention is to overcome the deficiency of above-mentioned prior art, proposed a kind of long device of annular laser optical cavity of controlling, utilize the refractive index of piezoelectric ceramic electric control resonant cavity inner drying air, realize control the ring laser optical cavity length.

Technical scheme of the present invention is achieved in that

Know-why of the present invention be according to " optical technology handbook " (the king Zhijiang River, Chen Xingpu etc., China Machine Press, the relation that provides in 1987:683) at 0.339 μ m～1.695 μ m spectral region inner drying air refraction n and state parameter:

$n=1+C\left(\mathrm{\&lambda;}\right)\left(\frac{P}{T}\right)---\left(4\right)$

Wherein, C (λ)=7.748 * (1+6.6063 * 10 ^-3λ ^-2) * 10 ^-3, P is the pressure (Pa) of air, and T is the absolute temperature (K) of air, and λ is light wavelength (μ m), draws as drawing a conclusion: by changing the pressure P or the temperature T of dry air, can control the refractive index n of dry air.

According to above-mentioned principle, the present invention has designed a kind of device that can control annular laser optical cavity length, and this device comprises thermally insulated container, adiabatic elasticity diaphragm, piezoelectric ceramic, and wherein thermally insulated container constitutes described device main body, on the thermally insulated container, be provided with connecing of being connected with ring laser and chew; The adiabatic elasticity diaphragm closely is fixed on the thermally insulated container, and thermally insulated container is divided into two space G and Q, charges into dry air in the capillary of the G space of thermally insulated container and the ring laser that is connected with this space; One end of piezoelectric ceramic is connected with the adiabatic elasticity diaphragm, and the other end is fixed on the thermally insulated container, utilizes the frequency stabilization servo system, and the voltage U on the piezoelectric ceramic is followed the tracks of change.

Piezoelectric ceramic in the above-mentioned control annular laser optical cavity growth device is a cylindrical shape, and the positive and negative electrode that can add the control supply voltage is arranged on this cylinder.During real work, in space G and the laser capillary that is attached thereto, charge into dry air, and the Q space is vacuumized.

Control the structure of annular laser optical cavity growth device by this, can get following relation:

(1) variation relation of air refraction and pressure

Is research object with space G with the ring laser capillary inner drying air that is attached thereto.If the pressure of air, temperature, volume are respectively P, T, V.Because therefore the pressure very low (1 standard atmospheric pressure) of air can be similar to and see ideal gas as, its state parameter satisfies The Ideal-Gas Equation:

$P=\frac{\mathrm{mRT}}{M}\frac{1}{V}---\left(5\right)$

Wherein, m is the quality of air, and M is the molal weight of air, and R is a universal gas constant.

If during the change in volume Δ V of air, corresponding pressure change Δ P, refractive index change delta n.Suppose that the gaseous state change procedure is adiabatic process, therefore following relation is arranged

$\mathrm{\&Delta;V}=-\frac{\mathrm{V\&Delta;P}}{\mathrm{\&kappa;P}}---\left(6\right)$

Wherein, κ is the adiabatic index of air.According to (4)～(6) formula, the variation relation that can get refractive index and pressure is

$\mathrm{\&Delta;n}=\frac{C\left(\mathrm{\&lambda;}\right)\mathrm{mR}}{\mathrm{\&kappa;MVP}}\mathrm{\&Delta;P}---\left(7\right)$

(2) variation relation of applied voltage on air refraction and the piezoelectric ceramic

If the shape of piezoelectric ceramic is a cylindrical shape,, can get the displacement l of piezoelectric ceramic then according to first kind piezoelectric equations _tWith the pass of the making alive Δ U of institute be

$\mathrm{\&Delta;}{l}_t=\frac{d_{31}{l}_t}{d_r}\mathrm{\&Delta;U}---\left(8\right)$

Wherein, l _tFor tube is high, d _rBe wall thickness, d ₃₁Piezoelectric modulus.

Suppose that the adiabatic elasticity diaphragm is that radius is the round and elastic thin plate of r, and establish and be shaped as spherical crown after its distortion, when piezoelectric ceramic 3 along l _tDirection changes delta l _tThe time, cause that the dry air change in volume is

$\mathrm{\&Delta;V}\&ap;-\frac{\mathrm{\&pi;}}{2}{\mathrm{<figure-callout\; id="2"\; label="r"\; filenames="C20051004197500131.png,C20051004197500141.png"\; state="\{\{state\}\}">r</figure-callout>}}^2\mathrm{\&Delta;}{l}_t---\left(9\right)$

Ignore the stress of adiabatic elasticity diaphragm, and by (7)～(9) formula, can get change of refractive and be piezoelectric ceramic

$\mathrm{\&Delta;n}=\frac{\mathrm{\&pi;}{r}^2{l}_t\mathrm{PC}\left(\mathrm{\&lambda;}\right)d_{31}}{2\mathrm{VT}{d}_r}\mathrm{\&Delta;U}---\left(10\right)$

If propagating the geometrical length of light path in dry air in the ring laser is l ₀, then frequency stabilization system is to the compensation rate Δ L of ring laser optical cavity length _MendWith the pass of the making alive Δ U of piezoelectric ceramic institute be

Δ L _Mend=l ₀Δ n=K Δ U (11)

Wherein, K is the sensitivity of the annular laser optical cavity growth device of control, and its expression formula is

$K=\frac{\mathrm{\&pi;}{r}^2{l}_t{l}_0\mathrm{PC}\left(\mathrm{\&lambda;}\right)d_{31}}{2\mathrm{VT}{d}_r}---\left(12\right)$

In the formula, C (λ) is the constant relevant with laser wavelength lambda, l _tFor the tube of cylindrical shape piezoelectric ceramic is high, d _rBe wall thickness, d ₃₁Be piezoelectric modulus, r is the radius of adiabatic elasticity diaphragm, l ₀Be the geometrical length of light path in dry air, that is to say ring laser length capillaceous, P, V, T are respectively pressure, volume and the temperature of dry air.

If control in the long device of annular laser optical cavity, the high l of tube of cylindrical shape piezoelectric ceramic _t=10mm, wall thickness d _r=0.1mm, piezoelectric coefficient d ₃₁=5 * 10 ^-11C/N, r ²/ V=0.05mm ^-1, the pressure P=1.01 of dry air * 10 ⁵Pa, the temperature T of dry air=25 ℃, the length of capillary B is 0.1m, then can calculate K=1.3 * 10 according to (12) formula ^-6MV ^-1

By above relational expression as seen, as long as change the dry air refractive index, just can change the compensation rate Δ L of ring laser optical cavity length _Mend, changed the compensation rate Δ L of ring laser optical cavity length _Mend, just can realize control, and the change of dry air refractive index being to be undertaken by the applied voltage that changes on the piezoelectric ceramic to the ring laser optical cavity length, detailed process is as follows:

(1) will control annular laser optical cavity growth device is connected with ring laser;

(2) in the capillary of the G space of thermally insulated container and the ring laser that is connected with this space, charge into dry air, and the Q space vacuumized, this G space and Q space are by being fixed on the adiabatic elasticity diaphragm on the thermally insulated container, with two spaces that thermally insulated container was separated into;

(3) make ring laser optical cavity length changes delta L when external environment _OutwardThe time, utilize the frequency stabilization servo system, the voltage U on the piezoelectric ceramic is followed the tracks of change, up to the size delta L that makes the optical cavity length compensation rate that is drawn by change amount Δ U _Mend=l ₀Δ n=K Δ U makes the variation delta L of ring laser optical cavity length with the external world _OutwardWhen basic identical, i.e. Δ L _Mend≈-Δ L _OutwardTill, wherein: l ₀For propagating the geometrical length of light path in dry air in the ring laser, Δ n is that air refraction changes, and K is the sensitivity of the annular laser optical cavity growth device of control;

(4) ring laser frequency of oscillation v is locked in the pairing frequency v of laser output power peak value ₀, promptly on the stabilized frequency of ring laser, to realize control to the ring laser optical cavity length.

Above-mentionedly voltage U on the piezoelectric ceramic is followed the tracks of the change process be: at first select the pairing frequency v of ring laser power output peak value ₀As the frequency stabilization point, again by the oscillator in the frequency stabilization servo circuit to applying modulation voltage on the piezoelectric ceramics power supply, obtain ring laser frequency of oscillation v and depart from v ₀Error feedback signal, make piezoelectric ceramics power supply voltage change Δ U according to this error feedback signal then, make ring laser optical cavity length changes delta L _Mend, finally make Δ L _Mend≈-Δ L _Outward, the optical cavity length of ring laser is stablized.

The present invention has following beneficial effect:

(1) because the annular laser optical cavity growth device of control of the present invention does not change the temperature of dry air, so do not have temperature gradient between it and the ring laser.

(2) because the response speed of the annular laser optical cavity growth device of control of the present invention depends primarily on the response speed of piezoelectric ceramic, adiabatic elasticity diaphragm and the response time that atmospheric pressure changes, therefore, it is fast to control short, toggle speed of adjustment time of annular laser optical cavity growth device and response speed.

(3) because the change amount of the annular laser optical cavity growth device of control of the present invention inner drying atmospheric pressure, the deformation quantity that depends on the adiabatic elasticity diaphragm, and it is irrelevant with the concrete shape of adiabatic elasticity diaphragm, therefore, when piezoelectric ceramic occurs bending and deformation, but control still steady operation of annular laser optical cavity growth device, and the performance of ring laser is not influenced.

(4) as can be known, the present invention controls annular laser optical cavity growth device and has very high sensitivity by sensitivity relation (12) formula.

(5) because the power consumption of the annular laser optical cavity growth device of control of the present invention comes from the flexible of piezoelectric ceramic, the deformation of adiabatic elasticity diaphragm, and the compression of dry air, expansion, and their variable quantity is all very little, therefore, it is very low to control the power consumption of annular laser optical cavity growth device.

(6) because the annular laser optical cavity growth device of control of the present invention is mainly controlled the optical cavity length of laser by piezoelectric ceramic, adiabatic elasticity diaphragm, it is simple in structure.

Description of drawings

The structure diagram of the existing automatically controlled chamber of piezoelectric element of Fig. 1 growth device

Fig. 2 adopts the structural representation of the total reflection type prism ring laser of existing temperature control chamber growth device

Fig. 3 the present invention controls the structure diagram of annular laser optical cavity growth device

Fig. 4 adopts the total reflection type prism ring laser schematic diagram of apparatus of the present invention

Fig. 5 adopts the reflection mirror ring laser schematic diagram of apparatus of the present invention

Fig. 6 the present invention controls the frequency stabilization theory diagram of annular laser optical cavity growth device

Embodiment

Below in conjunction with accompanying drawing the present invention is described in further detail:

With reference to Fig. 3, control of the present invention annular laser optical cavity growth device is mainly by cylindrical thermally insulated container 1, circular adiabatic elasticity diaphragm 2, and cylindrical shape piezoelectric ceramic 3 is formed.The main body of controlling annular laser optical cavity growth device is a thermally insulated container 1, and adiabatic elasticity diaphragm 2 closely is fixed on the thermally insulated container 1, and thermally insulated container 1 is divided into G, Q two parts.One end of piezoelectric ceramic 3 is connected with adiabatic elasticity diaphragm 2, and the other end is fixed on the thermally insulated container 1, and the positive and negative electrode that can add the control supply voltage is arranged on the piezoelectric ceramic 3, and thermally insulated container 1 is provided with to connect chews 4, and this connects chews 4 and can be connected with ring laser.

Embodiment 1

The control annular laser optical cavity growth device that the present invention proposes can be used in the frequency stabilization system of total reflection type prism ring laser, as shown in Figure 4.Controlling connecing in the annular laser optical cavity growth device chews 4 and is connected with capillary B in the total reflection type prism ring laser by heat-insulated pipe 5; 6 is the cavity of ring laser; 7～10 is total reflection prism, and 11～14 is protective cover, and A, B, C, D are four capillaries of ring laser.The capillary A of ring laser is by total reflection prism 9,10 sealings; and in pipe, charge into gain gas; the capillary B of ring laser is by protective cover 11,12 sealings; and in the capillary B of ring laser and space G, charge into the dry air of 1 standard atmospheric pressure, be vacuum in capillary C, the D of ring laser and the space Q.

The present invention controls the frequency stabilization system that annular laser optical cavity growth device and frequency stabilization servo circuit have been formed the total reflection type prism ring laser, and its frequency stabilization theory diagram as shown in Figure 6.Among Fig. 6, photodetector converts the light signal of ring laser output to the signal of telecommunication, frequency selective amplifier carries out filtering to the signal of telecommunication of output, phase-sensitive detector is that the signal of telecommunication of f and the reference signal on the oscillator compare with filtered frequency, draw error voltage signal, this error voltage signal is amplified by direct current amplifier.It is the modulated voltage signal of f that oscillator provides frequency.

After ring laser started, the frequency stabilization servo system was at first selected the pairing frequency v of ring laser power output peak value ₀As the frequency stabilization point, applying frequency by the oscillator in the frequency stabilization servo circuit on the power supply of piezoelectric ceramic again is the f modulation voltage, this voltage makes the length of piezoelectric ceramic 3 change with frequency f, cause that adiabatic elasticity diaphragm 2 vibrates by a small margin, cause the refractive index of ring laser capillary B inner drying gas also to change with frequency f, even the optical cavity length of ring laser changes with same frequency f, then ring laser frequency of oscillation v just produces the modulation that amplitude is δ v, thereby causes the modulation of ring laser power output.When the optical cavity length of ring laser just for being v corresponding to frequency of oscillation ₀Optical cavity length the time, the power output of ring laser changes with frequency 2f, this light signal can not pass through frequency selective amplifier through the signal of telecommunication that photodetector is transformed into, therefore, the frequency stabilization servo circuit does not produce signal and exports.When external environment makes ring laser optical cavity length changes delta L _OutwardThe time, ring laser frequency of oscillation v departs from v ₀, the power output of laser changes with frequency f, and this light signal is transformed into the signal of telecommunication through photodetector, sends into phase-sensitive detector after amplifying by frequency-selecting again, and the reference signal voltage of importing with oscillator compares, and exports a direct voltage V _Dc, this voltage V _DcSize and ring laser frequency of oscillation v depart from v ₀Size be directly proportional voltage V _DcThe positive and negative ring laser frequency of oscillation v that depends on depart from v ₀Direction, be an error voltage signal.Error voltage V _DcBe amplified to enough amplitudes by direct current amplifier, make the voltage that is added on the piezoelectric ceramic change Δ U, can change the length of piezoelectric ceramic 3, cause 2 deformation of adiabatic elasticity diaphragm, adjust the pressure and the refractive index of ring laser capillary B inner drying air, make ring laser optical cavity length changes delta L _MendThereby, make the frequency of oscillation v of ring laser tend to v ₀V is the closer to v for the ring laser frequency of oscillation ₀, error signal is more little, up to the error signal vanishing.At this moment, controlling annular laser optical cavity growth device makes the ring laser optical cavity length change Δ L _Mend, and Δ L is arranged _Mend≈-Δ L _OutwardSo ring laser frequency of oscillation v just is locked in v ₀The place has realized the stable of ring laser frequency of oscillation.

The sensitivity of the annular laser optical cavity growth device of control of the present invention in present embodiment 1 is used, can pass through following analysis verification:

If in the device of control total reflection type prism ring laser optical cavity length, the high l of tube of cylindrical shape piezoelectric ceramic _t=10mm, wall thickness d _r=0.1mm, piezoelectric coefficient d ₃₁=5 * 10 ^-11C/N, r ²/ V=0.05mm ^-1, pressure P=1.01 * 10 of dry air ⁵Pa, the temperature T of dry air=25 ℃, the length of capillary B is 0.1m, then can calculate K=1.3 * 10 according to (12) formula ^-6MV ^-1If the optical cavity length of ring laser is 0.28m, the total reflection prism material is a quartz glass, and the thermal coefficient of expansion of cavity is 5 * 10 ^-8℃ ^-1, it is 4.7 * 10 that the optical cavity length that can calculate ring laser varies with temperature ^-7M ℃ ^-1As seen, it is very high that the present invention controls the sensitivity of total reflection type prism ring laser optical cavity length device.

Embodiment 2

The frequency stabilization system that the annular laser optical cavity growth device of control of the present invention is used for reflecting the mirror ring laser, as shown in Figure 5.Control connecing in the annular laser optical cavity growth device and chew 4, be connected with capillary B in the reflection mirror ring laser by heat-insulated pipe 5.6 cavitys for reflection mirror ring laser, 15,16 is the Brewster window, 17～20 is speculum.These Brewster window 15,16 capillaries with ring laser are divided into A, B two parts, and simultaneously, Brewster window 15,16 is with the capillary B sealing of ring laser.Charging into gain media gas in the capillary A of ring laser, charge into the dry air of 1 standard atmospheric pressure in the capillary B of ring laser and the space G, is vacuum in the Q of space.Frequency stabilization system schematic diagram in the present embodiment, also as shown in Figure 6.

After ring laser started, the frequency stabilization servo system was at first selected the pairing frequency v of ring laser power output peak value ₀As the frequency stabilization point, on the power supply of piezoelectric ceramic, apply the modulation voltage that frequency is f by the oscillator in the frequency stabilization servo circuit again, this voltage makes the length of piezoelectric ceramic 3 change with frequency f, cause that adiabatic elasticity diaphragm 2 vibrates by a small margin, cause the refractive index of ring laser capillary B inner drying gas also to change with frequency f, even the optical cavity length of ring laser changes with same frequency f, then the frequency of oscillation v of ring laser generation amplitude is the modulation of δ v, thereby causes the modulation of ring laser power output.When the optical cavity length of ring laser just for being v corresponding to frequency of oscillation ₀Optical cavity length the time, the power output of ring laser changes with frequency 2f, but this light signal can not pass through frequency selective amplifier through the signal of telecommunication that photodetector is transformed into, therefore, the frequency stabilization servo circuit does not produce signal and exports.When external environment makes ring laser optical cavity length changes delta L _OutwardThe time, the frequency of oscillation v of ring laser departs from v ₀, the power output of laser changes with frequency f, and this light signal is transformed into the signal of telecommunication through photodetector, sends into phase-sensitive detector after amplifying by frequency-selecting again, and the reference signal voltage of importing with oscillator compares, and obtains a direct voltage V _Dc, this voltage V _DcSize and ring laser frequency of oscillation v depart from v ₀The error signal size be directly proportional voltage V _DcThe positive and negative ring laser frequency of oscillation v that depends on depart from v ₀Direction, be an error voltage signal.Error voltage V _DcBe amplified to enough amplitudes by direct current amplifier, make the voltage that is added on the piezoelectric ceramic change Δ U, can change the length of piezoelectric ceramic 3, cause 2 deformation of adiabatic elasticity diaphragm, adjust the pressure and the refractive index of ring laser capillary B inner drying air, make ring laser optical cavity length changes delta L _MendThereby, make the frequency of oscillation v of ring laser tend to v ₀V is the closer to v for the ring laser frequency of oscillation ₀, error signal is more little, up to the error signal vanishing.At this moment, controlling annular laser optical cavity growth device makes the ring laser optical cavity length change Δ L _Mend, and Δ L is arranged _Mend≈-Δ L _OutwardSo ring laser frequency of oscillation v just is locked in v ₀The place has realized the stable of ring laser frequency of oscillation.

The sensitivity of the annular laser optical cavity growth device of control of the present invention in present embodiment 2 is used, can pass through following analysis verification:

If control in the annular laser optical cavity growth device, the high l of tube of cylindrical shape piezoelectric ceramic _t=10mm, wall thickness d _r=0.1mm, piezoelectric coefficient d ₃₁=5 * 10 ^-11C/N, r ²/ V=0.05mm ^-1, pressure P=1.01 * 10 of dry air ⁵Pa, the temperature T of dry air=25 ℃, the length of capillary B is 0.1m, then can calculate K=1.3 * 10 according to (12) formula ^-6MV ^-1If the optical cavity length of reflection mirror ring laser is 0.3m, the thermal coefficient of expansion of cavity is 5 * 10 ^-8℃ ^-1, it is 1.4 * 10 that the optical cavity length that can calculate reflection mirror ring laser varies with temperature ^-8M ℃ ^-1As seen, it is very high that the present invention controls the sensitivity of annular laser optical cavity growth device.

To sum up, the control annular laser optical cavity growth device that the present invention proposes, little to the ring laser performance impact, be better than existing now two kinds of long devices of the annular laser optical cavity of control.Have that response speed is fast, highly sensitive, low in energy consumption, advantages of simple structure and simple, in the ring laser frequency stabilization system in high accuracy total reflection type prism laser gyro and reflection mirror laser gyro, be with a wide range of applications.But this embodiment does not constitute any restriction to invention, and obviously, described those skilled in the art can be without any creative work, and utilizes technical conceive of the present invention, makes the structure and the method that are not limited only to the embodiment of the invention.

Claims (4)

1. control the long device of annular laser optical cavity for one kind, it is characterized in that comprising: thermally insulated container (1), adiabatic elasticity diaphragm (2), piezoelectric ceramic (3) on the thermally insulated container (1), are provided with connecing of being connected with ring laser and chew (4); Adiabatic elasticity diaphragm (2) closely is fixed on the thermally insulated container (1), and thermally insulated container is divided into two space G and Q, charges into dry air in the capillary of the G space of thermally insulated container and the ring laser that is connected with this space; The two ends of piezoelectric ceramic (3) are connected with thermally insulated container (1) with adiabatic elasticity diaphragm (2) respectively, utilize the frequency stabilization servo system, and the voltage U on the piezoelectric ceramic (3) is followed the tracks of change.

2. the long device of the annular laser optical cavity of control according to claim 1 is characterized in that piezoelectric ceramic (3) is cylindrical shape, has the positive and negative electrode that adds the control supply voltage on this cylinder.

3. the long method of the annular laser optical cavity of control is installed in a utilization according to claim 1, be to change the dry air refractive index, by the compensation rate Δ L that changes dry air refraction index changing ring laser optical cavity length by the applied voltage that changes on the piezoelectric ceramic _Mend, by the compensation rate Δ L that changes the ring laser optical cavity length _MendRealization is to the control of ring laser optical cavity length, and detailed process is as follows:

(1) will control the long device of annular laser optical cavity is connected with ring laser;

(2) charge into dry air in the capillary of the G space of thermally insulated container and the ring laser that is connected with this space, and the Q space vacuumized, this G space and Q space are by being fixed on the adiabatic elasticity diaphragm on the thermally insulated container, with two spaces that thermally insulated container was separated into;

(3) make ring laser optical cavity length changes delta L when external environment _OutwardThe time, utilize the frequency stabilization servo system, the voltage U on the piezoelectric ceramic is followed the tracks of change, up to the size delta L that makes the ring laser optical cavity length compensation rate that is drawn by change amount Δ U _Mend=l ₀Δ n=K Δ U makes the variation delta L of ring laser optical cavity length with external environment _OutwardWhen basic identical, i.e. Δ L _Mend≈-Δ L _OutwardTill, wherein: l ₀For propagating the geometrical length of light path in dry air in the ring laser, Δ n is that air refraction changes, and K is the sensitivity of the annular laser optical cavity growth device of control;

(4) the frequency of oscillation v with ring laser is locked in the pairing frequency v of ring laser power output peak value ₀On, to realize control to the ring laser optical cavity length.

4. the method that the annular laser optical cavity of control according to claim 3 is long is wherein followed the tracks of the change process to the voltage U on the piezoelectric ceramic and is: at first selects the pairing frequency v of ring laser power output peak value ₀As the frequency stabilization point, again by the oscillator in the frequency stabilization servo circuit to applying modulation voltage on the piezoelectric ceramics power supply, obtain ring laser frequency of oscillation v and depart from v ₀Error feedback signal, make piezoelectric ceramics power supply voltage change Δ U according to this error feedback signal then, make the optical cavity length changes delta L of ring laser _Mend, finally make Δ L _Mend≈-Δ L _Outward, the optical cavity length of ring laser is stablized.

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