CN101008568A - No-blind-area four-mode stable solid state laser gyroscope - Google Patents

Abstract

This invention relates to one fix laser top device to measure rotation speed or relative angle position, which eliminates blind area without adding measurement error of special optical device to improve optical device, wherein, the method gets the total optical fix laser device without blind area; these devices comprise bias separation optical device, inverse light rotation and non-reverse light rotation device to avoid mode lock through different chambers by four linear bias modes.

Description

No-blind-area four-mode stable solid state laser gyroscope

Technical field

The present invention relates to be used to measure the solid-state gyrolaser of rotational speed or angle position.This equipment is in particular for aerospace applications.

Background technology

Developed lasergyro before about 30 years, sold widely now and use.Their operation is based on Sagnac (Sagnac) effect, and it causes coming spinning two-way ring shape laser cavity, the difference on the frequency Ω that asks of two optical emitting patterns that propagate, that be called as reverse propagation in the opposite direction.Typically, difference on the frequency Ω is:

Wherein L and A are respectively cavity length and area; λ is for getting rid of the Laser emission mean wavelength of Sagnac effect; ω is the angular rotational velocity (angular rotation speed) of lasergyro.

Be used for very accurately obtaining by the Ω value that two spectral analyses of launching the beat (beat) of light beams are obtained

Value.(advancing) beat striped (beat fringes) that advances during the position change of angle is carried out electronic counting, the relative value of position, angle also extremely accurately is provided.

Make lasergyro and need overcome several technical barriers.At first promptly be the quality that is related to the beat between two light beams, it determines the correction operation of this laser instrument.For the beat that will revise, the intensity that need launch on two directions is suitably stable and similar relatively.But under the situation of solid-state laser, can not guarantee stability and similarity owing to the competition (mode-mode competition) between the pattern, competition between the pattern makes one of two reverse communication modes monopolize available gain, and has damaged other pattern.Two-way emission problem of unstable for solid state ring laser can solve by implementing backward-acting ring (counter-reaction loop), and this ring is intended to the difference of the intensity of two reverse communication modes is controlled at about fixed value.This ring acts on this laser instrument by following manner, promptly, by its loss and the direction of propagation are connected, for example utilize reversible rotating element, non-reversible rotating element and polarizer (patented claim No.0303645), perhaps, for example utilize reversible rotating element, non-reversible rotating element and polarization transmitting crystal (patented claim No.0314598) by its gain is connected with the direction of propagation.In case controlled, these laser instrument emission two bundles have the light beam of the reverse propagation of strength of stability, and can be used as lasergyro.

Second technical barrier is related to low rotational speed, since lasergyro is only correctly worked when surpassing given rotational speed.Under low rotational speed, because the backscattering of the light of existing different optical element in the chamber, so the Sagnac Beat Signal can be that so-called locking disappears owing to the coupling of two reverse communication modes.The rotational velocity range of observing this phenomenon is commonly referred to as the blind area, and corresponding to tens thousand of hertz minimum beat frequency.This problem is not that solid-state laser is intrinsic: the gas laser gyroscope also meets with this problem.For the most common solution of second kind of lasergyro is exactly that it forces by giving, known motion and mechanically activated this device, and this motion manually is placed on outside the blind area as far as possible frequently.

Summary of the invention

The special optical device that the objective of the invention is to adopt dead zone-eliminating and do not increase measured deviation improves the required optical devices of instability that are used to control solid-state laser.Acquisition does not have moving-member, " optics fully " stable, non-blind area solid-state laser by this way.

Be more accurately, the present invention relates to a kind of lasergyro, it comprises at least:

The optical ring chamber;

Solid-state amplifier (amplifier) medium;

Driven (slaving) device, it comprises first optical module that is made of the first non-reversible optical rotator and optical element, this element or reversible optical rotator, or birefringence element, wherein at least one in this effect or the birefringence is adjustable;

And surveying instrument;

It is characterized in that described chamber also comprises:

Second optical module, it is made of the first spatial filtering device and the first polarization separation optical element;

The 3rd optical module, it is made of the second spatial filtering device and the second polarization separation optical element, and the second and the 3rd optical module is positioned at the first optical module both sides, and symmetrical mutually;

The 4th optical module, it is made of continuously first quarter-wave plate, the second non-reversible optical rotator and second quarter-wave plate, and the main shaft of second quarter-wave plate is perpendicular to the main shaft of first quarter-wave plate;

Thereby make the first linear polarization communication mode and second communication mode of linear polarization can be propagated with first direction perpendicular to the first linear polarization communication mode in the chamber, and be parallel to first communication mode and the 3rd communication mode of linear polarization and be parallel to second pattern and the 4th communication mode of linear polarization can be propagated with opposite direction in the chamber, wherein the main shaft of the main shaft of first quarter-wave plate and second quarter-wave plate is spent with respect to the linear polarization direction inclination 45 of four communication modes, and the optical frequency of four patterns is all different.

Advantageously, measuring system comprises:

Optical devices, it makes first communication mode and the 3rd communication mode interference on the one hand, and on the other hand, makes second pattern and four-mode interference;

Electrooptical device, it is used on the one hand determining that first optical frequency between first communication mode and the 3rd communication mode is poor, and on the other hand, is used for determining that second optical frequency between second communication mode and the four-mode is poor;

Electronic installation, it is used to obtain the difference between above-mentioned first frequency difference and above-mentioned second frequency difference.Common first frequency difference and second frequency difference are greater than about 100 KHz.In order to obtain the position, angle, final frequency difference can be carried out integration in time by electronics fringe count device.

Advantageously, the chamber comprises birefringent retarder elements.

In a preferred embodiment, polarization separation first optical element and second optical element are the birefringent retarder elements that has flat parallel side, and birefringence axis is with respect to plane inclination 45 degree of both sides.

Advantageously, slave unit comprises the 5th optical module at least, and it is made up of the 3rd non-reversible optical rotator and second optical element, this optical element or birefringence element, or reversible optical rotator, and their birefringence and reversible effect are adjustable; The first and the 3rd communication mode is passed through the first non-reversible optical rotator and first optical element.Particularly, this birefringence element is a birefringent retarder elements, for example quarter-wave plate.

Description of drawings

By reading following non-limitative illustration book and accompanying drawing, the present invention will be understood and be represented other advantage better, wherein:

Fig. 1 is the skeleton diagram according to lasergyro of the present invention;

Fig. 2 illustrates the principle of work of reversible optical rotator;

Fig. 3 illustrates the principle of work of non-reversible optical rotator;

Fig. 4 a illustrates the principle of work of polarization separation birefringent retarder elements;

Fig. 4 b illustrates the isoboles of the retardation plate of general Jones's form (Jones formalism);

Fig. 5 is illustrated in the work of first, second and the 3rd optical module on the direct direction of propagation;

Fig. 6 is illustrated in the variant of embodiment the work of first, second and the 3rd optical module on the direct direction of propagation;

Fig. 7 illustrates for first and second communication modes, the work of the 4th optical module.

Embodiment

Must realize three specific functions according to specific device of the present invention:

Automatically control the intensity of reverse communication mode;

Dead zone-eliminating;

Do not introduce measured deviation.

In order to realize these functions, this device produces four optical modes with the different frequency linear polarization in the chamber.First and second communication modes are propagated with first direction in inside, chamber, and second pattern is perpendicular in first pattern of the 4th optical module outside and linear polarization, and the 4th optical module inner loop around.Third and fourth pattern is propagated with opposite direction, and the 3rd communication mode is parallel to first pattern and linear polarization, and the 4th communication mode is parallel to second pattern of the 4th optical module outside and linear polarization, and the 4th optical module inner loop around.

Produce by lasergyro shown in Figure 1 according to the present invention and control this four patterns, wherein, optical element is reversible optical rotator.It mainly comprises:

Optical ring chamber 1, it comprises that at least one partially reflecting mirror 11 is with the outer reverse communication mode of process chamber;

Solid-state amplification medium 2;

Slave unit 3, it controls optical rotator 4 and 5 (dotted arrow on the figure);

Surveying instrument 6;

Optical system, it comprises:

о first optical module, it is made of the first non-reversible optical rotator 5 and reversible optical rotator 4;

о second optical module, it is made of the first spatial filtering device 7 and the first polarization separation optical element 8;

о the 3rd optical module, it is made of the second spatial filtering device 10 and the second polarization separation optical element 9, and the second and the 3rd optical module is positioned at the first optical module both sides, and symmetrical mutually;

The 4th optical module, it is connected and composed by first quarter-wave plate, 12, the second non-reversible optical rotator 13 and second quarter-wave plate 14, and the main shaft of second quarter-wave plate 14 is with respect to 90 ° of the main axis rotation of first quarter-wave plate.

Optical system comprises reversible optical rotator 4 and non-reversible optical rotator 5.Have when ripple be reflected in the optical module of this specific character after (go and return), when the effect stack of polarization rotation, the optics rotation of wave polarization is called as non-reversible.This optical module is called as non-reversible optical rotator.For example, the material with Faraday effect is a kind of like this material, that is, when placing magnetic field, rotation is by the plane of polarization of its light beam.This effect is irreversible.Therefore, the same light beam of transmission will make their plane of polarization rotate in the same direction in the opposite direction.This principle is shown in Figure 3.When linear polarized beam 101 when direct direction (direct sense) goes up assembly 5 by having Faraday effect (the last figure of Fig. 3), the polarization direction of this linear polarized beam 101 is rotated angle β.If we inject once more in the assembly with Faraday effect in the opposite direction and to propagate and its polarization direction is rotated the same light beam 103 of angle β at first, so in its polarization direction when this assembly by rotation angle β again, its total anglec of rotation is 2 β (figure below of Fig. 3) after reflection.

In traditional reversible spinner 4, the polarization direction is rotation+α on direct direction, and on the opposite direction of propagation rotation-α, so obtain initial polarization direction, shown in the block diagram of Fig. 2.

Optical system also comprises two polarization separation optical elements.There is multiple geometry, guarantees the separation of light beam.For example, Fig. 4 a illustrates birefringent retarder elements 8, and it separates light beam linearly.This retardation plate comprises two flat parallel side, and from the single axial birefringence crystal-cut, the single axial birefringence crystal is characterised in that ordinary optical coefficient and special optical coefficient.

Ordinary optical coefficient in the retardation plate be changed to sphere, and special optical coefficient be changed to ellipse, shown in Fig. 4 a dotted line.According among the figure by the preferred orientations (optical axis) shown in the double-head arrow that tilts, common and special optical coefficient equates.Retardation plate cuts along the plane of 45 degree that tilt from this direction.When first linear polarized beam 101 entered the entrance side of birefringent retarder elements with common incident bump, verified its do not change direction by retardation plate.When second light beam 102 of the linear polarization perpendicular to light beam 101 enters the entrance side of birefringent retarder elements with common incident bump, verified when passing through retardation plate its spatial deviation.Therefore, when two light beams 101 and 102 left birefringent retarder elements, shown in Fig. 4 a, they were parallel to each other and with interval d separately, d depends on the optical characteristics and the thickness of retardation plate at interval.

The work of optical system as shown in Figure 5.This illustrates the path of first communication mode 101, and the path of second communication mode 102 by first optical module and linear polarization.Before the first spatial filtering device 7, the linear polarization of first pattern 101 is positioned at the plane of paper, and the linear polarization of second pattern 102 is perpendicular to the plane of paper.These polarization directions are shown in straight arrow.Obviously, first spatial light filter (filtering) is kept these polarization directions.

Has intensity I ₁First communication mode by the first polarization separation optical element 8, be parallel to its incident direction and penetrate, as shown in the figure offset d.Next, it is by the reversible spinner 4 and the first non-reversible spinner 5.As a result, be rotated angle [alpha] by its polarization direction behind first element, and by being rotated the angle alpha+beta behind second element.In the exit of first spinner, the linear polarization of first pattern can be decomposed into two vertical vectors that divide, and vector was parallel to inceptive direction in first minute, and intensity equals initial strength I ₁Multiply by coefficient cos ²The value of (alpha+beta), second fen vector is perpendicular to inceptive direction, and intensity equals initial strength I ₁Multiply by coefficient sin ²The value of (alpha+beta).Vector was by the second polarization separation optical element 9 in first minute, and by skew-d, this second optical element is symmetrical in first optical element and is positioned, thereby this divides vector to pass through second optical filter 10 and unattenuated, and second light filter is positioned on the axle identical with first light filter.Second fen vector do not have skew (the some arrow of Fig. 5), thereby can not pass through second light filter by the second polarization separation optical element.Therefore endways, first pattern is with coefficient cos ²(alpha+beta) decay.Equally, second communication mode 102 also is attenuated and illustrates with identical coefficient.Third and fourth communication mode of Chuan Boing also is attenuated with common coefficient in the opposite direction.Prove that easily this second coefficient is cos ²(alpha-beta).Must be noted that the light beam loss in the beam separation of component can finally be sent on the photoelectric detector of servo system, thereby the beam intensity data are provided.

Have to be noted that also reversible phase differential often appears between two polarization states of this device.This phase differential is useful, because it is in response to the deviation that can avoid the frequency locking, but its value needn't be enough high.If desired, can cause additional phase differential by the birefringence element that in the chamber, inserts.

Therefore, pattern is according to its direction of propagation difference that decays, and the importance of the effect that polarization experienced of two-mode is directly depended in this decay.Therefore, by changing among two value α or the β at least one through the effect that slave unit experienced, may change the intensity of reverse communication mode by the polarization of two-mode.Therefore, the intensity of different mode is controlled in about constant value.

In this structure, be first and second communication modes on the one hand, be third and fourth communication mode on the other hand, they all are attenuated in an identical manner.By adopting two reaction rings independently, each ring influences different polarization, can obtain the differential declines value in the mode propagation in the same direction.This principle is shown in Figure 6.Between the second and the 3rd optical module, insert two optical modules, wherein the second and the 3rd optical module respectively comprises spatial light filter and polarization separation optical element, the optical module of each insertion by non-reversible optical rotator 5 or 51 and reversible optical rotator 4 or 41 form; Independently control these two set (ensembles) by unshowned slave unit among Fig. 6.Certainly, the distance of separation d between two light beams should enough make different spinners be set up.In this structure, can place amplification medium 2 on the separation path of light beam as shown in Figure 6.Then, optical pumping takes place at two difference places, diaphragm 10 guarantees the space overlap of the light beam that tripping device is outer.Variant of the present invention has additional advantage, and four-mode can separate fully when considering gain, has therefore eliminated the competitive effect between pattern.

Fig. 7 illustrates the work of the 4th optical module.When linear polarization optics pattern 101 (the right arrow of Fig. 7) is passed through first quarter-wave plate 12, if the main shaft by this retardation plate of double-head arrow representative is tilted 45 degree with respect to the polarization direction, this pattern withdraws from (whole semicircular ring arrows of Fig. 7) with right circular polarization (right circular polarization) so.

When by the non-reversible spinner 13 of second optics, this circular polarization ripple experiences non-reversible phase differential γ.Then, this ripple is changed into linearly polarized wave once more by second quarter-wave plate 14, and the main shaft of second quarter-wave plate 14 is perpendicular to the main shaft of first quarter-wave plate.Therefore, in pattern, introduce non-reversible phase differential, and keep the linear polarization of ripple by this 4th optical module.Certainly, if this ripple by linear polarization and perpendicular to 101 directions, it is changed into circular (left circular) polarized wave in a left side so, and experiences non-reversible phase differential-γ.

Therefore, adopt above device may in the chamber, produce two and connect two four-modes of propagating in the opposite direction (two by two), changeably they are decayed with controlled manner, thereby they are maintained identical strength level, and these patterns are introduced reversible and non-reversible phase differential.In order to determine natural mode (natural mode) and frequency thereof, adopt the Jones matrix form.Under normal conditions, this is to represent the influence of the assembly in the optical propagation modes by 2 * 2 matrixes of reference perpendicular to the plane of the direction of propagation of optical mode.In this case, we adopt the general Jones form of the situation be suitable for having in the chamber two travel paths, as we have seen.The path is called as or " top " path and following or " end " path.In this case, representational matrix is 4 * 4 matrixes.The orthogonalization parameter (x, y) in, they the axle on plane, by having four branch vector (T perpendicular to direction of beam propagation _x, T _y, B _x, B _y) vector the electric field of this optical mode, wherein (T are described _x, T _y) be Jones vector along the electric field in path, top, (B _x, B _y) be Jones vector along the electric field in the path, the end shown in Fig. 4 b, wherein this optical path is indicated on respect to its optical axis 8 and carries out in the single axial birefringence retardation plate of 45 ° of cuttings.

In order to obtain the final influence of branch vector in all chambeies, we only determine expression, and these divide nature (natural) state of the product of vectorial different matrixes.This product needs not to be tradable, so matrix can change according to direction of beam propagation.

In this form, can see, when the first polarization separation optical element that is made of with respect to its optical axis cutting 45 degree birefringece crystal is passed through, carry out following work as assembly with two inlets and two outlets, " top " and " end " on the suitable direction of propagation:

Send B _xAnd T _x, it is parallel to the plain shaft on himself and propagates,

By on Ty and 0, sending they and " raising " B respectively _yAnd T _y, B _yAnd T _yBeing parallel to special axle propagates.

Vector T _yStop or do not aim at by crystal on side face, and can not vibrate with the propagation axis in chamber.

When passing through in the opposite direction, crystal nature " reduction " B _yAnd T _y, and B _xAnd T _xRemain unchanged.

φ/2 phase differential are introduced in the birefringence of whole chamber between two polarization states.Therefore, represent the Jones matrix of the first or second polarization separation optical element according to the direction of propagation, wherein, light beam rises:

$C_{\↑}\left(\mathrm{\φ}\right)=\left[\begin{array}{cccc}{e}^{-\mathrm{i\φ}/4}& 0& 0& 0\\ 0& 0& 0& e^{\mathrm{i\φ}/4}\\ 0& 0& e^{-\mathrm{i\φ}/4}& 0\\ 0& 0& 0& 0\end{array}\right]$

When passing through with the opposite direction of propagation, first (or second) polarization separation optical element reduces light beam.Therefore matrix is:

$C_{\↓}\left(\mathrm{\φ}\right)=\left[\begin{array}{cccc}{e}^{-\mathrm{i\φ}/4}& 0& 0& 0\\ 0& 0& 0& 0\\ 0& 0& e^{-\mathrm{i\φ}/4}& 0\\ 0& e^{\mathrm{i\φ}/4}& 0& 0\end{array}\right]$

Spatial filtering device matrix is:

&lt;math> <mrow> <mi>D</mi> <mo>=</mo> &lt;mfenced open='[' close=']'> &lt;mtable> &lt;mtr> &lt;mtd> <mn>0</mn> </mtd> &lt;mtd> <mn>0</mn> </mtd> &lt;mtd> <mn>0</mn> </mtd> &lt;mtd> <mn>0</mn> </mtd> </mtr> &lt;mtr> &lt;mtd> <mn>0</mn> </mtd> &lt;mtd> <mn>0</mn> </mtd> &lt;mtd> <mn>0</mn> </mtd> &lt;mtd> <mn>0</mn> </mtd> </mtr> &lt;mtr> &lt;mtd> <mn>0</mn> </mtd> &lt;mtd> <mn>0</mn> </mtd> &lt;mtd> <mn>1</mn> </mtd> &lt;mtd> <mn>0</mn> </mtd> </mtr> &lt;mtr> &lt;mtd> <mn>0</mn> </mtd> &lt;mtd> <mn>0</mn> </mtd> &lt;mtd> <mn>0</mn> </mtd> &lt;mtd> <mn>1</mn> </mtd> </mtr> </mtable> </mfenced> </mfenced> </mrow> </math>

Do not introduce the element of transversal effect, its 2 * 2Jones matrix is matrix m, will have 4 * 4 following matrix forms:

Therefore, the matrix of other element that occurs in the device can be written as follows:

For being called as the reversible spinner that passes through on the sense of rotation of direct direction, matrix R ₊(α) be:

$R_{+}\left(\mathrm{\&alpha;}\right)=\left[\begin{array}{cccc}\cos \left(\mathrm{\&alpha;}\right)& -\sin \left(\mathrm{\&alpha;}\right)& 0& 0\\ \sin \left(\mathrm{\&alpha;}\right)& \cos \left(\mathrm{\&alpha;}\right)& 0& 0\\ 0& 0& \cos \left(\mathrm{\&alpha;}\right)& -\sin \left(\mathrm{\&alpha;}\right)\\ 0& 0& \sin \left(\mathrm{\&alpha;}\right)& \cos \left(\mathrm{\&alpha;}\right)\end{array}\right]$

For being called as the reversible spinner that passes through on the rightabout opposite sense of rotation, matrix R (α) is:

$R_{-}\left(\mathrm{\&alpha;}\right)=\left[\begin{array}{cccc}\cos \left(\mathrm{\&alpha;}\right)& \sin \left(\mathrm{\&alpha;}\right)& 0& 0\\ -\sin \left(\mathrm{\&alpha;}\right)& \cos \left(\mathrm{\&alpha;}\right)& 0& 0\\ 0& 0& \cos \left(\mathrm{\&alpha;}\right)& \sin \left(\mathrm{\&alpha;}\right)\\ 0& 0& -\sin \left(\mathrm{\&alpha;}\right)& \cos \left(\mathrm{\&alpha;}\right)\end{array}\right]$

For non-reversible spinner, this matrix is independent of the direction of propagation, and is

$F\left(\mathrm{\&beta;}\right)=\left[\begin{array}{cccc}\cos \left(\mathrm{\&beta;}\right)& -\sin \left(\mathrm{\&beta;}\right)& 0& 0\\ \sin \left(\mathrm{\&beta;}\right)& \cos \left(\mathrm{\&beta;}\right)& 0& 0\\ 0& 0& \cos \left(\mathrm{\&beta;}\right)& -\sin \left(\mathrm{\&beta;}\right)\\ 0& 0& \sin \left(\mathrm{\&beta;}\right)& \cos \left(\mathrm{\&beta;}\right)\end{array}\right]$

For the quarter-wave plate that is rotated 45 degree, this matrix is:

$L_1=\frac{1}{\sqrt{2}}\left[\begin{array}{cccc}1& -\mathrm{<figure-callout\; id="0"\; label="i"\; filenames="A20061000899400161.png"\; state="\{\{state\}\}">i</figure-callout>}& 0& 0\\ -i& 1& 0& 0\\ 0& 0& 1& -\mathrm{<figure-callout\; id="0"\; label="i"\; filenames="A20061000899400161.png"\; state="\{\{state\}\}">i</figure-callout>}\\ 0& 0& -i& 1\end{array}\right]$

For the quarter-wave plate that is rotated 135 degree, this matrix is:

${\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="A20061000899400151.png,A20061000899400181.png"\; state="\{\{state\}\}">L</figure-callout>}}_2=\frac{1}{\sqrt{2}}\left[\begin{array}{cccc}1& \mathrm{<figure-callout\; id="0"\; label="i"\; filenames="A20061000899400161.png"\; state="\{\{state\}\}">i</figure-callout>}& 0& 0\\ i& 1& 0& 0\\ 0& 0& 1& \mathrm{<figure-callout\; id="0"\; label="i"\; filenames="A20061000899400161.png"\; state="\{\{state\}\}">i</figure-callout>}\\ 0& 0& i& 1\end{array}\right]$

For in directly direction and the in the opposite direction pattern of propagation, the matrix J of all optical assemblies that can obtain in the chamber, to exist by simple multiplication ₊And J _-:

$J_{+}={\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="A20061000899400151.png,A20061000899400181.png"\; state="\{\{state\}\}">L</figure-callout>}}_2.F\left(\mathrm{\&gamma;}\right){.L}_1.D{.C}_{\&DownArrow;}\left(\mathrm{\&phi;}\right).F\left(\mathrm{\&beta;}\right){.R}_{+}\left(\mathrm{\&alpha;}\right){.C}_{\&UpArrow;}\left(\mathrm{\&phi;}\right).D=$

$\left[\begin{array}{cccc}0& 0& 0& 0\\ 0& 0& 0& 0\\ 0& 0& \cos (\mathrm{\&alpha;}+\mathrm{\&beta;})e^{-i(\mathrm{\&phi;}/2-\mathrm{\&gamma;})}& 0\\ 0& 0& 0& \cos (\mathrm{\&alpha;}+\mathrm{\&beta;})e^{i(\mathrm{\&phi;}/2-\mathrm{\&gamma;})}\end{array}\right]$

And

$J.=L_1.F\left(\mathrm{\&gamma;}\right).{\mathrm{<figure-callout\; id="2"\; label="L"\; filenames="A20061000899400151.png,A20061000899400181.png"\; state="\{\{state\}\}">L</figure-callout>}}_2.D.C_{\&DownArrow;}\left(\mathrm{\&phi;}\right).F\left(\mathrm{\&beta;}\right).R.\left(\mathrm{\&alpha;}\right).C_{\&UpArrow;}\left(\mathrm{\&phi;}\right).D=$

$\left[\begin{array}{cccc}0& 0& 0& 0\\ 0& 0& 0& 0\\ 0& 0& \cos (\mathrm{\&alpha;}-\mathrm{\&beta;})e^{-i(\mathrm{\&phi;}/2+\mathrm{\&gamma;})}& 0\\ 0& 0& 0& \cos (\mathrm{\&alpha;}-\mathrm{\&beta;})e^{i(\mathrm{\&phi;}/2+\mathrm{\&gamma;})}\end{array}\right]$

Know matrix J ₊And J _-The state of nature that helps the definite optical mode that can in the chamber, propagate.On each direction of propagation, there are two different state of nature along x and y axle, that is, and four state of nature altogether are as follows:

(+, be x): the state of nature of propagating for the horizontal linearity polarization on first direction of propagation;

(+, be y): the state of nature of propagating for vertical linear polarisation on first direction of propagation;

(-, be x): the state of nature of propagating for the horizontal linearity polarization on the opposite direction of propagation;

(-, be y): the state of nature of propagating for vertical linear polarisation on the opposite direction of propagation;

State of nature (+, x) and (+, mould y) (modulus) equals cos (alpha+beta), wherein, state of nature (, x) and (, mould y) equals cos (alpha-beta).This mould is different with the direction of propagation, therefore may control reverse communication mode with the constant intensity difference by changing one of two factor alpha or β.

If lasergyro is not rotated, typically, length is that the frequency v of optical mode is relevant with phase differential Φ in the loop laser chamber of L, and this pattern is whenever rotated once this phase differential of back experience Φ around the chamber:

Wherein n is an integer

For given n value, therefore the frequency of different state of nature is:

For mould (+, y), $v(+,x)\frac{c}{L}[n+\frac{\mathrm{\&phi;}/2-\mathrm{\&gamma;}}{2\mathrm{\&pi;}}]$

For mould (x, y), $v(+,y)=\frac{c}{L}[n-\frac{\mathrm{\&phi;}/2-\mathrm{\&gamma;}}{2\mathrm{\&pi;}}]$

For mould (, x), $v(-,x)=\frac{c}{L}[n+\frac{\mathrm{\&phi;}/2+\mathrm{\&gamma;}}{2\mathrm{\&pi;}}]$

For mould (, y), $v(-,y)=\frac{c}{L}[n-\frac{\mathrm{\&phi;}/2+\mathrm{\&gamma;}}{2\mathrm{\&pi;}}]$

When the chamber rotates, make the frequency of natural frequency skew ± Ω/2 by the Sagnac effect, its symbol depends on the mode propagation direction.The frequency of this pattern is in this case:

For mould (+, x), $v(+,x)=\frac{c}{L}[n+\frac{\mathrm{\&phi;}/2-\mathrm{\&gamma;}}{2\mathrm{\&pi;}}]+\frac{\mathrm{\&Omega;}}{2}$

For mould (+, y), $v(+,y)=\frac{c}{L}[n-\frac{\mathrm{\&phi;}/2-\mathrm{\&gamma;}}{2\mathrm{\&pi;}}]+\frac{\mathrm{\&Omega;}}{2}$

For mould (, x), $v(-,x)=\frac{c}{L}[n+\frac{\mathrm{\&phi;}/2+\mathrm{\&gamma;}}{2\mathrm{\&pi;}}]-\frac{\mathrm{\&Omega;}}{2}$

For mould (, y), $v(-,y)=\frac{c}{L}[n-\frac{\mathrm{\&phi;}/2+\mathrm{\&gamma;}}{2\mathrm{\&pi;}}]-\frac{\mathrm{\&Omega;}}{2}$

Strictly speaking, if accurately determine the frequency of optical mode, then the variation of the cavity length that causes owing to birefringence and Sagnac effect should be considered into.As can be seen, these effects are negligible, do not influence the precision of measurement.

For fear of the coupling between pattern with the blind area occurs, should guarantee sufficient frequency separation.Therefore, (c/2 π L) γ and (c/2 π L) (-2 γ) must be greater than the determined one group of minimum value of the working range that is used for lasergyro by expectation.In order to guarantee this condition, suitably simple formation reversible and the optics of non-reversible spinner and the size of geometric parameter.

On the one hand light beam (+, x) and (, beat x), on the other hand light beam (+, y) and (, beat y) produces two beat frequency v1 and v2, makes:

$v_1=|v(-,x)-v(+,x)=\frac{c}{L}\frac{\mathrm{\&gamma;}}{\mathrm{\&pi;}}-\mathrm{\&Omega;}|$ And ${\mathrm{<figure-callout\; id="2"\; label="v"\; filenames="A20061000899400151.png,A20061000899400181.png"\; state="\{\{state\}\}">v</figure-callout>}}_2=|v(-,y)-v(+,y)=\frac{c}{L}\frac{\mathrm{\&gamma;}}{\mathrm{\&pi;}}+\mathrm{\&Omega;}|$

The difference Δ v of two frequencies is:

Δv＝v ₁-v ₂＝2Ω

Therefore, obtain beat frequency Ω by measuring Δ v, to determine angular rotational velocity.This value is independent of chamber deviate and any fluctuation wherein.

Adopt surveying instrument to carry out the different operating of determining difference on the frequency Δ v, this surveying instrument comprises:

Optical devices, its make on the one hand first communication mode (+, x) with the 3rd communication mode (, x) interference, and make on the other hand second communication mode (+, y) with the 4th communication mode (, y) interference; By make on the one hand (+, x) with (, y) interference and make on the other hand (+, y) with (, x) interference, variant is possible;

Electrooptical device, it determines the first optical frequency difference v between first communication mode and the 3rd communication mode on the one hand ₁, and the second frequency difference v between definite on the other hand second communication mode and the 4th communication mode ₂

Electronic installation, it is used to obtain first frequency difference and second frequency difference v ₂Between difference on the frequency Δ v.

It is perhaps useful to introduce optical standard type Fabry-Perot (Fabry-Perot) in the chamber.Certainly, it can not very good (fine) so that can not avoid the too strong coupling of different mode frequency.Advantageously, with respect to the tilt side of this standard of direction of beam propagation, to avoid the propagation of glass-reflected.

Certainly may assemble a plurality ofly according to lasergyro of the present invention, setting up along three out-of-alignment angular velocity measurement systems, this system comprises and for example is installed in structural three lasergyro of standard machinery.

Claims (8)

1. according to the fixing lasergyro of turning axle measured angular speed or relative angle position, it comprises at least:

Optical ring chamber (1);

Solid-state amplification medium (2);

Slave unit (3), it comprises first optical module that is made of the first non-reversible optical rotator (5) and optical element at least, described optical element or reversible optical rotator (4), or birefringence element, and in this effect or the birefringence at least one is adjustable;

And surveying instrument (6);

It is characterized in that described chamber (1) also comprises:

Second optical module, it is made of the first spatial filtering device (7) and the first polarization separation optical element (8);

The 3rd optical module, it is made of the second spatial filtering device (10) and the second polarization separation optical element (9), and the second and the 3rd optical module is positioned at the first optical module both sides and symmetrical mutually;

The 4th optical module, it is made of continuously first quarter-wave plate (12), the second non-reversible optical rotator (13) and second quarter-wave plate (14), and the main shaft of second quarter-wave plate (14) is perpendicular to the main shaft of first quarter-wave plate;

Thereby make the first linear polarization communication mode and second communication mode of linear polarization can be propagated with first direction perpendicular to the first linear polarization communication mode in the chamber, be parallel to first pattern and the 3rd communication mode of linear polarization and be parallel to second pattern and the 4th communication mode of linear polarization can be propagated with opposite direction in the chamber, and the main shaft of the main shaft of first quarter-wave plate and second quarter-wave plate is spent with respect to the linear polarization direction inclination 45 of four communication modes, and the optical frequency of four patterns is all different.

2. lasergyro according to claim 1 is characterized in that this chamber comprises birefringent retarder elements, and it helps to cause or increase the difference on the frequency between the vertical polarization attitude.

3. lasergyro according to claim 1 is characterized in that, this measurement mechanism (6) comprising:

Optical devices, it makes first communication mode and the 3rd communication mode interference on the one hand, makes second pattern and four-mode interference on the other hand;

Electrooptical device, it is used on the one hand determining that first optical frequency between first communication mode and the 3rd communication mode is poor, and is used for second frequency difference between definite second communication mode and the 4th communication mode on the other hand;

Electronic installation, it is used to obtain the frequency difference between above-mentioned first frequency difference and above-mentioned second frequency difference.

4. lasergyro according to claim 3 is characterized in that, first frequency difference and second frequency difference are greater than about 100 KHz.

5. according to one of aforesaid right requirement described lasergyro, it is characterized in that, first optical element (8) and the second polarization separation optical element (9) are the single axial birefringence retardation plates, have flat parallel side, and optical axis is with respect to about 45 degree of the plane inclination of side.

6. according to one of aforesaid right requirement described lasergyro, it is characterized in that, slave unit (3) comprises the 5th optical module at least, it is made of the 3rd non-reversible optical rotator (51) and second optical element, described optical element or reversible optical rotator (41), or birefringence element, and effect or birefringent at least one be adjustable, and be independent of first optical module and regulate; First communication mode and the 3rd communication mode are by the first non-reversible optical rotator and first optical element, and the 3rd communication mode and the 4th communication mode are by the 3rd non-reversible optical rotator and second optical element.

7. according to one of aforesaid right requirement described lasergyro, it is characterized in that chamber (1) comprises optical standard type Fabry-Perot Fabry-Perot.

8. along the system of three disalignment measured angular speed or relative angle position, it is characterized in that, its this system comprises three lasergyro according to one of aforesaid right requirement, and these lasergyro are positioned in different directions and are installed on the standard machinery structure.

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