CN113607062B - Micro-actuator displacement and inclination angle measuring device and method - Google Patents

Abstract

The present invention provides a micro-actuator displacement and inclination measuring device and method. The laser resonator is composed of a fixed cavity mirror and an independent cavity mirror. Between the independent cavity mirror and the laser gain tube, an anti-reflection-coated glass plate is placed obliquely along the laser axis, and its surface reflects two weak beams incident on the plane driven by the actuator. The mirror is folded back and coupled back to resonate to form a bifurcated cavity laser feedback. During the movement of the actuator, the light intensity variation fringes formed by the laser feedback are received and recorded by the photodetector, and the displacement and inclination of the actuator are calculated according to the period and envelope characteristics of the feedback fringes. The invention can simultaneously measure the displacement amount and the inclination angle of the micro-displacement actuator in the process of linear expansion and contraction, and evaluate its performance index.

Description

Micro-actuator displacement and inclination measuring device and method

technical field

The invention relates to the technical field of optical measurement, in particular to a micro-actuator displacement and inclination measurement device.

Background technique

Precisely controllable linear displacement has important applications in many fields such as manufacturing, materials, and scientific research. With the continuous improvement of displacement accuracy requirements, micro-displacement actuators driven by stepper motors or servo motors, piezoelectric ceramics, voice coil motors, etc. have been gradually developed, and their performance indicators will determine the processing or measurement accuracy.

In addition to the linear elongation along the axis, the actuator may also have a yaw angle relative to the axis when the actuator is driven by the power supply, which is mainly caused by the inhomogeneity of the material and structure, and the difference in driving voltage. Therefore, during the working process of the actuator, on the one hand, it requires high resolution of the displacement with the change of the driving source (such as voltage signal), good linearity, and minimizes the displacement hysteresis; on the other hand, it requires good directionality during the displacement process. , minimize the inclination relative to the axis.

In order to test the displacement performance and inclination angle of different types of actuators, an interferometer with higher precision and traceability to the laser wavelength is generally used. However, in the optical path of the interferometer, the components for measuring the displacement and measuring the inclination angle are independent, that is, only one of the two can be measured. In practical applications, such as piezoelectric ceramic actuators, the inclination angle during the elongation process needs to be measured at the same time. size, it cannot be measured by an interferometer. In addition, the displacement and inclination measurement components of the laser interferometer are large in size and weight. During the driving process of the micro-displacement actuator, the force state will be significantly changed, which will bring systematic errors to the measurement.

SUMMARY OF THE INVENTION

The purpose of the present invention is to solve one of the above technical problems, and to provide a device that can simultaneously measure the micro-actuator's slight inclination and displacement changes.

In order to achieve the above object, the technical scheme adopted in the present invention is:

Micro-actuator displacement and inclination measurement device, including:

Laser gain tube: one end is connected to a fixed cavity mirror coated with a high reflection film, and one end is connected to a glass window coated with an antireflection coating;

Independent cavity mirror: It is set apart from the laser gain tube mirror, and the side coated with the high reflective film faces the glass window side, and is set in parallel with the fixed cavity mirror to form a laser resonant cavity. The distance between the two is the length of the cavity;

Optical glass sheet: It is set between the gain tube glass window and the independent cavity mirror, and is inclined at a certain angle to the laser beam in the resonant cavity, including the first plane on the side of the gain tube and the first plane on the side of the independent cavity mirror. Two planes, two planes are coated with antireflection coating;

The actuator is arranged on the reflected light path of the laser passing through the optical glass sheet, and is adjusted to generate micro-displacement along the direction of the laser beam;

Plane mirror: set on the end face of the actuator facing the optical glass sheet, the two beams of light reflected by the first plane and the second plane of the optical glass sheet are returned to the laser resonator in the same way; between the optical glass sheet and the plane mirror forming a bifurcated cavity attached to the laser resonator;

Photodetector: set on the side of the fixed cavity mirror away from the independent cavity mirror, used to detect the tail light output from the fixed cavity mirror and convert it into an electrical signal that changes with time;

Data processing unit: connected with the photodetector, according to the detected light intensity change curve of the laser bifurcated cavity feedback, the laser feedback fringes are measured, and the displacement and inclination of the actuator are calculated;

The displacement is the displacement of the actuator toward or away from the optical glass sheet in the direction of the laser axis in the bifurcated cavity under the driving of the power supply, and the inclination angle is the angular change relative to the propagation direction of the laser axis.

In some embodiments of the present invention, the data processing unit is configured to calculate the actuator displacement ΔL as follows:

ΔL=λ/2(M+m);

Among them, λ is the laser wavelength, M is the integer part of the feedback fringe, m is the fractional part of the feedback fringe obtained according to the change phase of the light intensity, and obtained according to the light intensity change curve detected by the photodetector;

The data processing unit is configured to calculate the inclination angle of the actuator as follows

Where: D is the distance between the beam _Er and the beam _Er' , ε is the length difference coefficient of the bifurcated cavity caused by the displacement and inclination of the micro-actuator, and N is a length in the light intensity change curve during the extension and contraction of the actuator. The number of cycles of the lower half-wavelength fluctuation of the periodic envelope; 10800 is the conversion factor from radians to degrees;

E _r is the light emitted by the emitted laser through the gain tube, after the first plane F ₁ of the optical glass sheet is reflected to the plane mirror, then propagated to the plane mirror, and then reflected back to the laser resonator through the plane mirror; _Er' is the emitted light The laser is refracted from the first plane F ₁ of the optical glass sheet to the second plane F ₂ through the gain tube, and after being reflected to the first plane F ₁ by the second plane F ₂ , the optical glass sheet is refracted through the first plane F ₁ and propagated. to the plane mirror, and then the light reflected back to the resonator through the plane mirror.

In some embodiments of the present invention, a method for measuring displacement and inclination angle of a micro-actuator is further provided, using the aforementioned testing device, comprising the following steps:

The step of calculating the actuator displacement ΔL: obtain the integer part M and the fractional part m of the laser feedback fringes according to the photodetector image;

ΔL=λ/2(M+m);

步骤：Calculate the inclination of the actuator

step:

Where: D is the distance between the beam _Er and the beam _Er' , ε is the length difference coefficient of the bifurcated cavity caused by the displacement and inclination of the micro-actuator, and N is a length in the light intensity change curve during the extension and contraction of the actuator. The number of cycles of the lower half-wavelength fluctuation of the periodic envelope; 10800 is the conversion factor from radians to degrees;

E _r is the light emitted by the emitted laser through the gain tube, after the first plane F ₁ of the optical glass sheet is reflected to the plane mirror, then propagated to the plane mirror, and then reflected back to the laser resonator through the plane mirror; _Er' is the emitted light The laser is refracted from the first plane F ₁ of the optical glass sheet to the second plane F ₂ through the gain tube, and after being reflected to the first plane F ₁ by the second plane F ₂ , the optical glass sheet is refracted through the first plane F ₁ and propagated. to the plane mirror, and then the light reflected back to the resonator through the plane mirror.

In some embodiments of the present invention, the method further includes:

Calculate the inclination data of the first group of actuators at the first angle;

Rotate the actuator by 90 degrees and repeat the steps of calculating the inclination of the actuator;

Calculate the inclination angle data of the second group of actuators at the second angle;

Combining the first set of inclination angle data and the second set of inclination angle data, the actual inclination angle and the inclination direction during the displacement process of the actuator are obtained.

Compared with the prior art, the advantages and positive effects of the present invention are:

(1) The present invention can simultaneously measure the displacement and the inclination angle of the micro-displacement actuator in the process of linear extension, and evaluate the performance index of the actuation.

(2) The present invention can calculate the actuator displacement and inclination angle by calculating the number of feedback fringes during the measurement process, and the linearity is high; the magnitude of the actuator displacement and inclination angle can be associated with the laser wavelength, so that the measurement can be traced back to the source Length benchmark - laser wavelength.

Description of drawings

1 is a schematic structural diagram of an actuator displacement and inclination measuring device of the present invention;

2 is a schematic diagram of the optical path of the actuator displacement and inclination measuring device of the present invention;

Fig. 3 is a state diagram when the actuator is not displaced;

Fig. 4 is a state diagram when the actuator is displaced with an inclination angle;

FIG. 5 is a graph showing the change of the laser light intensity along the displacement of the actuator along the laser axis with the tilt angle state.

In the above figures:

1. Laser gain tube, 2. Fixed cavity mirror, 3. Antireflection window, 4. Independent cavity mirror, 5. Glass sheet, 6. Actuator, 7. Plane mirror, 8. Photodetector, 9. data processing unit.

Detailed ways

Hereinafter, the present invention will be specifically described through exemplary embodiments. It should be understood, however, that elements, structures and features of one embodiment may be beneficially combined in other embodiments without further recitation.

In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", etc. is based on the positional relationship shown in the accompanying drawings, which is only for the convenience of description The present invention and simplified description do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operate in a particular orientation, and therefore should not be construed as limiting the invention.

It should be noted that when an element is referred to as being "disposed on," "connected to," or "fixed to" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed to indicate or imply relative importance.

The present invention provides a micro-actuator displacement and inclination measuring device, which can be, for example, a micro-displacement actuator such as piezoelectric ceramics and voice coil motors.

Referring to Figures 3 and 4, the directions of laser propagation from left to right are shown, and this direction is defined as the initial propagation direction of the laser. The displacement described here means that the actuator 6 is driven along the bifurcated cavity by the power supply. The displacement of the middle laser axis close to or away from the optical glass sheet is shown in the upward or downward direction as shown in Figure 3; the inclination angle mentioned here refers to the angle change of the actuator relative to the propagation direction of the laser axis, which is expressed as The swing direction shown in Figure 4. Among them, the reason for the displacement and inclination of the actuator is that after the voltage is applied to the actuator 6, each end face of the actuator 6 will be elongated, and this elongation movement is carried out close to the initial propagation direction of the laser; , the non-uniformity of the structure, the elongation motion generated by the actuator 6 is non-uniform, and therefore, an inclination angle will be generated.

Refer to Figure 1 for the structure of the measuring device, including:

Laser gain tube 1: one end is connected to a fixed cavity mirror 2 coated with a high reflection film, and one end is connected to a glass window 3 coated with an antireflection coating; its light exit direction is toward the independent cavity mirror 4; the diameter of the capillary in the gain tube 1 is small and deviates from the capillary Light outside the diameter range cannot be returned through gain tube 1;

Independent cavity mirror 4: It is arranged _at an interval with the laser gain tube mirror 1, and the side coated with the highly reflective film faces the glass window side, and is arranged in parallel with the fixed cavity mirror 2 to form a laser resonant cavity. Resonator cavity length;

Optical glass sheet 5: It is arranged between the gain tube glass window 3 and the independent cavity mirror 4, and is inclined at a certain angle to the laser beam in the resonant cavity. The thickness is d, including the first plane F ₁ on the side close to the gain tube 1 and the second plane F ₂ on the side close to the independent cavity mirror, and the two planes are coated with anti-reflection films; For reflection, the actuator 6 is arranged on the reflected light path of the laser light passing through the optical glass sheet; in some embodiments, anti-reflection films can be provided on both sides of the optical glass sheet 3, and after the anti-reflection films are provided, the reflection of light can be reduced coefficient to reduce the amount of reflection of the light after passing through the optical glass sheet 3; the optical glass sheet 5 is located in the resonant cavity, which is at an angle of θ with the laser, and the angle can be selected according to needs, for example, it can be set to 45°;

The actuator 6 is arranged on the reflected light path of the laser through the optical glass sheet, and is adjusted to generate micro-displacement along the direction of the laser beam;

Plane mirror 7: arranged on the end face of the actuator facing the optical glass sheet 5, parallel to the initial propagation direction of the laser light; reflecting the _two beams of light reflected by the _first plane F1 and the second plane F2 of the optical glass sheet A bifurcated cavity attached to the laser resonator is formed between the optical glass sheet 5 and the plane mirror 7, and the length of the bifurcated cavity is l _b , which is defined as the incident laser from the gain tube end 1 to the optical The distance between the incident point on the glass sheet 5 and the plane mirror 7; when the actuator 6 rotates, the length of the bifurcated cavity will change; the direction of the laser beam reflected by the optical glass sheet 3 to the plane mirror 7 is Laser axis propagation direction;

Photodetector 8: arranged on the side of the fixed cavity mirror away from the independent cavity mirror, and used to detect the tail light output from the fixed cavity mirror and convert it into an electrical signal that changes with time;

Data processing unit 9 : connected to the photodetector 8 , according to the intensity change curve of the detected laser bifurcated cavity feedback light, the laser feedback fringes are measured, and the displacement and inclination of the actuator 6 are calculated.

The data processing unit calculates the displacement ΔL of the actuator 6 based on the following method:

ΔL=λ/2(M+m);

Among them, λ is the laser wavelength, M is the integer part of the feedback fringe, m is the fractional part of the feedback fringe obtained according to the change phase of the light intensity, and obtained according to the light intensity change curve detected by the photodetector;

The data processing unit is configured to calculate the inclination angle of the actuator as follows

以及位移量ΔL决定的小量，N为致动器伸缩过程中光强变化曲线中一个长周期包络下半波长波动的周期数；10800为弧度变换至以分为单位的角度的变换因子；Among them: D is the distance between the beam _Er and the beam _Er' , ε is the length difference coefficient of the bifurcated cavity caused by the displacement and the inclination of the microactuator, which is determined by the inclination of the actuator

and the small amount determined by the displacement amount ΔL, N is the number of cycles of the lower half-wavelength fluctuation of a long-period envelope in the light intensity change curve during the expansion and contraction of the actuator; 10800 is the conversion factor from radians to angles in minutes;

_Er is the light that the laser passes through the gain tube, after the first plane F ₁ of the optical glass sheet is reflected to the plane mirror, then propagates to the plane mirror, and then is reflected back to the laser resonator through the plane mirror; _Er' is the emitted laser light Through the gain tube, the first plane F1 of the optical glass sheet ₅ is refracted to the _second plane F2, and after being reflected to the _first plane F1 by the _second plane F2, the optical glass sheet is refracted through the _first plane F1 and propagated. to the plane mirror, and then the light reflected back to the resonator through the plane mirror.

Hereinafter, the calculation principle of the present invention will be explained in detail.

The resonant cavity of the standing wave laser is composed of a fixed cavity mirror 2 and an independent cavity mirror 4, and the oscillating light field satisfies the resonance condition. When the output laser is reflected by the optical surface outside the resonator, it returns to the resonator and overlaps with the oscillating light field to form interference, that is, laser feedback or self-mixing interference. When the external optical reflection surface (usually a mirror with a specific reflectivity) changes, the phase of the feedback light returning to the resonator is correspondingly changed, which can cause the laser light intensity to change to form feedback fringes.

An optical glass sheet 5 is placed in the laser resonator, and its inclination along the laser axis will reflect part of the light in the cavity to the outside of the laser, and a plane mirror 7 is set on the reflected light path to re-enter the resonator along the original path. The laser feedback is formed, which makes the laser light intensity change.

Since the optical glass sheet 5 in the cavity and the plane mirror 7 outside the cavity form a bifurcated cavity structure independent of the laser resonator, the surface reflectivity of the element is low, and the two beams of re-incident light formed by the bifurcated cavity will not affect the laser oscillation, but will Change the output light intensity to produce a laser feedback effect. When the out-of-cavity flat mirror 7 is displaced along the laser direction, the light intensity will change periodically. According to laser physics, when the bifurcated cavity flat mirror 7 moves by half the wavelength of the light, the laser light intensity changes by one cycle, that is, a feedback fringe is formed. When the mirror is driven by a linear displacement actuator, the displacement of the micro-actuator can be obtained by measuring the number of feedback fringes.

Specifically, a schematic diagram of the optical path propagation of the laser after passing through the actuator displacement and inclination measuring device is shown in FIG. 2 . Hereinafter, the method for measuring the inclination angle and displacement of the micro-actuator by using the device provided by the present invention will be described with reference to the accompanying drawings.

The initial light wave emitted by the fixed cavity mirror 2 propagates in the right direction of the figure. The complex amplitude of the electric field vector of the initial light wave is E ₀ . It propagates in the positive direction in the resonator cavity to the right, and is amplified by the laser gain tube 1 and attenuated by the antireflection window 3 Then, the complex amplitude of the electric field vector becomes E _i .

Since both the front and rear surfaces of the optical glass sheet 5 in the cavity can reflect the laser light, there are actually two parallel laser beams in the bifurcated cavity:

One beam is E _r , which is the light _emitted by the gain tube 1 after being reflected by the first plane F ₁ of the optical glass sheet 5 to the plane reflector 7 , then propagated to the plane reflector 7 , and then refracted by the plane reflector 7 . ;

One beam is _Er' , the laser beam E _i emitted by the gain tube 1 is refracted by the first plane F ₁ of the optical glass sheet 5 to the second plane F ₂ , and reflected to the first plane F ₁ by the second plane F ₂ A plane F ₁ refracts the optical glass sheet 5 , propagates to the plane reflecting mirror 7 , and then passes the light refracted back by the plane reflecting mirror 7 .

The reflected light E _r and E _r' are reflected by the plane mirror 7 and return to the original path, and then refracted once on the first plane F ₁ and the second plane F ₂ to generate three beams:

E _r : reflected by the first plane F ₁ to form reflected light E _r , the reflected light returns along the capillary gain tube; refracted along the first plane F ₁ , and further refracted along the second plane F ₂ , and passed through the second plane F ₂ passes through to form refracted light E _rt ; is refracted by the first plane F ₁ , and is further reflected along the second plane F ₂ , then refracted by the first plane F ₁ , and passes through the first plane F ₁ to form a refracted light _Err' ;

_Er' : reflected by the first plane F ₁ to form reflected light _Er'r ; refracted along the first plane F ₁ , and further refracted along the second plane F ₂ , and passed through the second plane F ₂ to form a refraction Light _Er't ; is refracted by the _first plane F1, and further reflected along the _second plane F2, then refracted by the _first plane F1, and pierced through the _first plane F1 to form a folded light _{Er'r '} , the reflected light returns along the capillary gain tube.

Due to the small diameter of the capillary in the gain tube 1, the aforementioned Err _' , _Er't do not return to the gain cavity. At the same time, the surface of the optical glass sheet 5 is coated with an anti-reflection film, and the reflection coefficient is very small. Therefore, only two or less reflections on the two surfaces of the official glass sheet 5 are considered. The high-order reflected light intensity is too small and can be ignored. Therefore, only consider Err, _{Er'r '} return to the gain cavity.

The return of the optical path from the fixed cavity mirror 2 to the independent cavity mirror 4 is as follows.

E _i propagates from the transmitted light E _t of the optical glass sheet 5 to the independent cavity mirror 4 and is reflected, and the complex amplitude of the electric field vector becomes E ₁ . It returns to the original path and passes through the optical glass sheet 5 again. After being reflected and transmitted by the two surfaces, it is reflected once. The light will be along the original directions of _Ert and _Er't , Err _' respectively, and cannot enter the laser gain tube 1, and only the transmitted light E2 can return to the fixed cavity mirror ₂ through the capillary.

To sum up, in the optical path, the light returning to the resonator includes: Err, _{Er'r '} , and _E2 .

The calculation principle for calculating the displacement and inclination of the microactuator is as follows.

It is known that the refractive index of air is n ₀ , the refractive index of glass is n ₁ , the incident angle of the laser in the resonant cavity to the optical glass sheet 5 is θ _i =θ, the reflection angle θ _r =θ, and the refraction angle is:

θ _t =arcsin(n ₀ /n ₁ ·sinθ).

The optical path difference from _Er and _Er' to the plane mirror 7 can be calculated according to the aforementioned indexes:

Then the optical path difference of Err and _{Er'r '} returning to the incident point is: 2Δl.

Then the phase delay amount of Err and _{Er'r '} is: 2Δφ=4πΔl/λ.

Further, the complex amplitude of the electric field vector of each light in the resonant cavity can be calculated after passing through the independent cavity mirror 4, the optical glass sheet 5 and the plane mirror 7:

Among them, g is the gain coefficient of the active medium, la is the effective length of the active medium (He-Ne laser capillary gain tube _{), gl a is} the one-way gain obtained by the laser passing through the gain tube once in the resonator, and L' is the laser resonator The equivalent physical cavity length of , k is the wave vector: k=2π/λ.

In the process of calculating the equivalent physical cavity length of the laser resonator, considering the refractive index of the laser gain medium, the antireflection window 3, and the optical glass 5, we get:

Then according to the self-consistent condition, the light field from the fixed cavity mirror 2 goes back and forth in the cavity for one week, and after returning to the fixed cavity mirror 2, it should be consistent with the initial state, there are:

E ₀ =E ₂ +E _rr +E _r'r' ;

which is:

At the same time, for the optical glass sheet 7 coated with an anti-reflection coating on the surface, the reflectance is much less than 1, while the transmittance is approximately equal to 1. Simplifying Equation (3) and discarding the high-order small quantities, the expression of the laser gain can be obtained as:

in:

l ₁ =l+l _b -L', l ₂ =l+l _b +Δl-L'.

When the length l _b of the bifurcated cavity changes, the laser light intensity produces sinusoidal modulation with a period of λ2, that is, when the flat mirror 7 is driven by the actuator, the laser light intensity changes by one period (feedback fringes) for every displacement of λ2, which results in The total displacement ΔL (linear elongation) of the actuator is:

ΔL=λ/2(M+m); (5)

Among them, M is the integer part of the feedback stripes, and m is the fractional part of the feedback stripes obtained according to the phase of the light intensity change. It can be obtained by the data processing unit 9, and the light wave image obtained by reference to the detection, the whole cycle number is M, and the part less than one cycle is converted into a fractional part m according to the phase.

经反射镜7后两光束沿各自轴线方向的位移量不相等，相互之间有位差。则根据式(4)中l₁和l₂变为：After the voltage is applied to the actuator 6, the elongation of each point on its end surface is inconsistent, so that the plane mirror 7 has a small deflection angle relative to the surface normal

After passing through the mirror 7, the displacements of the two light beams along their respective axis directions are not equal, and there is a position difference between them. Then according to formula (4), l ₁ and l ₂ become:

l ₁ '=l+(1-ε/2)l _b -ΔL-L',l ₂ '=l+(1+ε/2)l _b -ΔL+Δl-L'; (6)

Substituting Equation (6) into Equation (4), the change curve of the laser light intensity formed during the displacement process of the actuator 6 can be calculated as shown in FIG. 5 .

It can be seen that with the displacement of the actuator 6, the length l _b of the bifurcated cavity changes, and a long-period envelope appears on the light intensity fluctuation curve with a period of λ2. Then the 6-minute average displacement of the actuator can be obtained by substituting into equation (5) according to the fluctuation period of the light intensity. And the size of the yaw angle during the extension process of the actuator 6 is calculated according to the number N of half-wavelength fluctuation periods under a long-period envelope in the light intensity curve:

Thus, the linear extension ΔL of the actuator 6 and the yaw angle along the x-axis direction can be obtained simultaneously

Calculate the inclination data of the first group of actuators at the first angle;

Rotate the actuator by 90 degrees and repeat the steps of calculating the inclination of the actuator;

Calculate the inclination angle data of the second group of actuators at the second angle;

Combining the first set of inclination angle data and the second set of inclination angle data, the actual inclination angle and the inclination direction during the displacement process of the actuator are obtained.

和ζ，可以得到致动器6在伸长过程中的实际倾斜角和倾斜方向。For example, the actuator 6 can be rotated 90° relative to the laser axis, and continuing the above test, the pitch angle ζ along the y-axis direction can be obtained. Combining two inclinations

and ζ, the actual inclination angle and inclination direction of the actuator 6 during the elongation process can be obtained.

The above are only preferred embodiments of the present invention, and are not intended to limit the present invention in other forms. Any person skilled in the art may use the technical content disclosed above to make changes or modifications to equivalent changes. The embodiments are applied to other fields, but any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention still belong to the protection scope of the technical solutions of the present invention without departing from the content of the technical solutions of the present invention.

Claims (4)

1. Micro-actuator displacement and inclination measuring device characterized in that includes:

laser gain tube: one end of the fixed cavity mirror is connected with the high-reflection film plated fixed cavity mirror, and the other end of the fixed cavity mirror is connected with the anti-reflection film plated glass window sheet;

independent chamber mirror: the laser gain tube is arranged at an interval, one surface plated with the high reflection film faces one side of the glass window sheet and is arranged in parallel with the fixed cavity mirror to form a laser resonant cavity, and the laser resonant cavity is arranged at an interval between the high reflection film and the fixed cavity mirror, namely the length of the laser resonant cavity;

optical glass sheet: the laser gain tube is arranged between the glass window of the laser gain tube and the independent cavity mirror, is inclined at a certain angle with the laser beam in the laser resonant cavity, and comprises a first plane close to one side of the laser gain tube and a second plane close to one side of the independent cavity mirror, and the two planes are plated with antireflection films;

the micro actuator is arranged on a reflected light path of the laser passing through the optical glass sheet and is adjusted to generate micro displacement along the direction of the laser beam;

a plane mirror: the two light primary paths reflected by the first plane and the second plane of the reflective optical glass sheet return to the laser resonant cavity; a laser branched cavity attached to the laser resonant cavity is formed between the optical glass sheet and the plane reflector;

a photoelectric detector: the tail light detector is arranged on one side of the fixed cavity mirror, which is far away from the independent cavity mirror, and is used for detecting tail light output from the fixed cavity mirror and converting the tail light into an electric signal which changes along with time;

a data processing unit: the laser feedback stripe is measured according to the detected light intensity change curve when the laser branched cavity is fed back, and the displacement and the inclination angle of the micro actuator are calculated;

the displacement is the displacement of the micro-actuator approaching or departing from the optical glass sheet along the laser axis direction in the laser bifurcation cavity under the driving of the power supply, and the inclination angle is the angle change relative to the laser axis propagation direction.

2. A micro-actuator displacement and tilt angle measuring device according to claim 1, wherein:

the data processing unit is configured to calculate the micro-actuator displacement Δ L as follows:

ΔL＝λ/2(M+m)；

wherein, λ is the laser wavelength, M is the feedback stripe integer part, M is the feedback stripe decimal part obtained according to the light intensity variation phase, and the feedback stripe decimal part is obtained according to the light intensity variation curve detected by the photoelectric detector;

the data processing unit is configured to calculate the tilt angle θ of the micro-actuator as follows:

wherein: d is a laser beam E _r And a laser beam E _r' The distance between the micro-actuators is epsilon, the laser bifurcation cavity length difference coefficient caused by the displacement and the inclination angle of the micro-actuator is epsilon, and N is the periodicity of half-wavelength fluctuation under one long-period envelope in a light intensity change curve in the telescopic process of the micro-actuator; 10800 is a radian to angle conversion factor;

E _r for emitting laser through the laser gain tube, on the first plane F of the optical glass sheet ₁ After being reflected to the plane mirror, the light is transmitted to the plane mirror and then reflected back to the laser resonant cavity by the plane mirror; e _r' For emitting laser through the laser gain tube, on the first plane F of the optical glass sheet ₁ Refracted to a second plane F ₂ Through the second plane F ₂ Reflected to a first plane F ₁ Then passes through a first plane F ₁ And refracting the optical glass sheet, transmitting the optical glass sheet to the plane reflector, and reflecting the light returned to the laser resonant cavity by the plane reflector.

3. A method of measuring displacement and tilt of a micro-actuator using the measuring device of claim 2, comprising the steps of:

calculating the displacement Delta L of the micro-actuator: obtaining an integer part M and a decimal part M of the laser feedback stripes according to the image of the photoelectric detector;

ΔL＝λ/2(M+m)；

calculating the inclination angle theta of the micro actuator:

wherein: d is a laser beam E _r And a laser beam E _r' The distance between the two is epsilon, the epsilon is a laser bifurcation cavity length difference coefficient caused by the displacement and the inclination angle of the micro-actuator, and N is the light intensity in the expansion and contraction process of the micro-actuatorThe number of cycles of half-wavelength fluctuation under one long-period envelope in the variation curve; 10800 is a radian to angle conversion factor;

E _r in a first plane F of the optical glass sheet for emitting laser through the laser gain tube ₁ After being reflected to the plane mirror, the light is transmitted to the plane mirror and then reflected back to the laser resonant cavity by the plane mirror; e _r' For emitting laser through the laser gain tube, on the first plane F of the optical glass sheet ₁ Refracted to a second plane F ₂ Through the second plane F ₂ Reflected to a first plane F ₁ Then passes through a first plane F ₁ And refracting the optical glass sheet, transmitting the optical glass sheet to the plane reflector, and reflecting the light returned to the laser resonant cavity by the plane reflector.

4. A method of micro-actuator displacement and tilt measurement according to claim 3, further comprising:

obtaining tilt data for a first set of micro-actuators at a first angle calculation;

rotating the micro actuator by 90 degrees, and repeating the calculation step of the inclination angle of the micro actuator;

obtaining tilt data for a second set of micro-actuators at a second angle calculation;

and combining the first set of inclination angle data and the second set of inclination angle data to obtain the actual inclination angle and the actual inclination direction in the micro-actuator displacement process.

Images