CN104614551A - Combined optical grating micromechanical acceleration sensor and acceleration measurement method thereof - Google Patents

Abstract

The invention discloses a combined grating micro-mechanical acceleration sensor and a method for measuring acceleration thereof. The sensor includes four sets of transmitting and receiving devices, an enhancement layer, a first fixed base, a second fixed base, a curved cantilever beam, and an upper capacitor plate , a lower capacitive plate, a signal processing module and a current driving module. The invention greatly reduces the volume of the system, and introduces comb electrodes and capacitive plates as electrostatic force recovery closed-loop devices, which can accurately detect the displacement and expand the dynamic range of the detector; the pulsed light intensity generated by a group of gratings Change the signal to lock the position where the slope of the gentle light intensity change signal generated by another group of gratings is the largest, so as to measure the displacement caused by the acceleration pulling the mass block; realize the miniaturization and high precision of the sensing system, and are widely used in aviation and military fields. There are very broad application prospects.

Description

Combination grating micromachined acceleration sensor and its method for measuring acceleration

technical field

The invention relates to the technical field of sensors, in particular to a combined grating micromachined acceleration sensor and a method for measuring acceleration thereof.

Background technique

In recent years, with the development of integrated circuit manufacturing technology and micro-machining technology, micro-mechanical sensors based on these two manufacturing technologies have developed rapidly. With its small size, light weight, low power consumption, low cost, easy integration, strong overload capability and mass production, micromechanical sensors have quickly occupied various sensor fields, such as micromechanical acceleration sensors. At present, with the improvement of the performance requirements of micro-mechanical displacement sensors, especially the continuous expansion of the application requirements of medium and high-precision displacement sensing, the research of high-precision micro-optical machine acceleration sensors combined with optical measurement and micro-optical technology has become an important Direction of development.

Acceleration sensors are mainly divided into inductive acceleration sensors, capacitive acceleration sensors, and tunnel acceleration sensors in the existing registration. Although there are many types, the highest displacement accuracy of the current acceleration sensor can only reach the ng level. A micro-displacement measuring device of the ng level is a double-grating MEMS displacement sensor designed by Sandia National Lab in the United States. The intensity is used to measure the tiny acceleration, and the grating is locked at the most sensitive position for measuring the acceleration through the change of the signal light intensity. Since the light intensity change curve is relatively flat, it is impossible to accurately distinguish whether the change of light intensity is caused by the external environment or the acceleration, so it cannot be accurate. Lock the grating at the most sensitive position for acceleration, and the measurement accuracy is not high.

Contents of the invention

The object of the present invention is to provide a combined grating micromachined acceleration sensor and a method for measuring acceleration thereof, aiming at the shortcomings of the prior art.

The purpose of the present invention is achieved through the following technical solutions: a combined grating micro-mechanical acceleration sensor, including four groups of transmitting and receiving devices, an enhancement layer, a first fixed base, a second fixed base, a curved cantilever beam, and an upper capacitor Plate, lower capacitor plate, signal processing module and current drive module; one end of the upper capacitor plate is connected to the first fixed base, and the other end is connected to the second fixed base; a quality block area is provided in the middle of the upper capacitor plate; The left and right sides of the mass block area are etched back-shaped cantilever beams, and a T-shaped grating area connected to the mass block area is respectively provided at the upper and lower ends, and a channel is etched around the mass block area and the T-shaped grating area on the upper capacitor plate; The channel has a comb-like structure on the four corners of the mass block area, the comb-like teeth formed by the comb-like structure in the mass block area serve as the first comb-like electrodes, and the comb-like teeth paired with the first comb-like electrodes serve as the second comb The second comb-shaped electrode is attracted or repelled by the first comb-shaped electrode by electrostatic force.

The two side edges of the top surface of the T-shaped grating area have downward rectangular grooves, the groove depth of which is 600-900nm, and the second moving grating is etched on the groove, and the top of the T-shaped grating area The first moving grating having the same structure as the second moving grating is symmetrically etched inside the plane; the first fixed base and the second fixed base are both fixed on the enhancement and reflection layer and electrically connected with the enhancement and reflection layer.

A first fixed grating having the same structure as the first moving grating is etched on the lower capacitive plate at positions corresponding to the four first moving gratings on the upper capacitive plate, and a position corresponding to the four second moving gratings is etched with The second fixed grating with the same second moving grating structure; the distance between the initial lateral position of the first fixed grating and the initial lateral position of the first movable grating in the direction perpendicular to the grating is 295-305nm; the second fixed grating The distance between the lateral initial position of the second moving grating and the lateral initial position of the second moving grating in the direction perpendicular to the grating is 163-167nm; the lower capacitor plate is fixed on the anti-reflection layer and is insulated from the anti-reflection layer.

Each group of transmitting and receiving devices includes two groups of transmitting receivers, and each group of transmitting and receiving devices includes a light source, a beam splitter, a first infrared photodetector, a first focusing lens group, a second infrared photodetector and a second infrared photodetector. Focusing lens group; the two light sources of each group of transmitting and receiving devices are respectively placed directly above the first moving grating and the second moving grating of the upper capacitive plate, and a beam splitter is provided below the light source, the first infrared photodetector and the second moving grating The two infrared photodetectors are symmetrically placed on both sides of the light source, the first focusing lens group is placed directly below the first infrared photodetector, and the second focusing lens group is placed directly below the second infrared photodetector; An infrared photodetector and eight second infrared photodetectors are all connected to the signal processing module; both sides of the lower capacitive plate are connected through leads and then connected to the current drive module; both sides of the enhancement layer are connected through leads and connected to the current A driving module; the current driving module is connected with the signal processing module.

The light source is an infrared 1530nm light source with collimated beam expansion; the antireflection layer is formed by sequentially coating 600nm SiO ₂ and 800nm Si ₃ N ₄ on the Si substrate.

The thicknesses of the first moving grating, the second moving grating, the first fixed grating and the second fixed grating are all 950-965nm, the number of gratings is 30-80, the period T is 1493-1500nm, and the duty cycle is uniform. 0.45-0.5; the air gap between the first moving grating and the first fixed grating is 300-400nm; the air gap between the second moving grating and the second fixed grating is 1000nm-1200nm.

Further, the light source is a vertical cavity surface emitting laser.

A method for measuring acceleration using the above-mentioned combined grating micromachined acceleration sensor, comprising the following steps:

The light emitted by the two light sources of each group of transmitting and receiving devices passes through the beam splitter to generate two laser beams, wherein one laser beam of the two light sources is irradiated to the area without grating on the upper capacitor plate and then reflected, and the reflected beam passes through the first focusing lens The group is irradiated on the first infrared photodetector; the other laser beam from one light source passes through the first moving grating of the upper capacitive plate, the first fixed grating of the lower capacitive plate and the anti-reflection layer in turn, and the light beam reflected by the anti-reflection layer passes through The second focusing lens group is irradiated onto the second infrared photodetector; another laser beam from another light source passes through the second moving grating of the upper capacitive plate, the second fixed grating of the lower capacitive plate, and the enhancement and reflection layer in sequence, and then passes through the enhancement and reflection The light beam reflected by the layer is irradiated onto the second infrared photodetector through the second focusing lens group;

The light intensity signals received by the two first infrared photodetectors and the two second infrared photodetectors of each group of transmitting and receiving devices are sent to the signal processing module for comparison and analysis, and the noise is filtered out by differential technology to obtain the general Wood abnormally smooth Light intensity change signal and special Wood anomaly pulsed light intensity change signal; the current drive module outputs current to the upper capacitor plate and the lower capacitor plate, and adjust the longitudinal interval of the two capacitor plates by adjusting the magnitude of the current to obtain different line width Special Wood anomaly pulsed light intensity change signal, when the line width of the obtained pulsed light intensity change signal is the narrowest, lock the current given to the capacitor plate at this time; when the upper capacitor plate and the lower capacitor plate are pulled by the mass block due to acceleration When a lateral relative displacement occurs, a general Wood anomalous light intensity change signal and a special Wood anomaly pulsed light intensity change signal are generated, and the current supplied to the first comb-shaped electrode and the second comb-shaped electrode is adjusted so that the first moving grating and the first The horizontal relative position of the fixed grating is kept at the position where the slope of the gentle light intensity change curve is the largest. This position is the relative position at which the second moving grating and the second fixed grating generate pulsed light intensity signal peaks at the same time. Using the extremely narrow line width of the pulse , lock the current given to the comb-shaped electrode at this time, and record it as the initial horizontal position, that is, the position where the slope of the gentle light intensity change curve is the largest; , drive the first comb-shaped electrode and the second comb-shaped electrode through the current drive module, pull the moving grating back to the locked lateral initial position, calculate the output current, and calculate according to the elastic coefficient of the cantilever beam and the mass Output the input acceleration; the four groups of accelerations obtained by analyzing the signals collected by the eight first infrared photodetectors and eight second infrared photodetectors are averaged to obtain the final acceleration; if it is caused by external vibrations The interval between the upper capacitive plate and the lower capacitive plate changes, so that the pulse signal disappears, and the current drive module adjusts the output current again until the pulsed light intensity signal reappears.

The beneficial effects of the present invention are: when the upper and lower gratings are slightly displaced due to the acceleration of the mass block, the reflected light intensity of one set of gratings will produce pulse-like changes, and the reflected light intensity of the other set of gratings will produce relatively gentle changes , using the extremely narrow line width of the pulsed light intensity signal, the comb electrode locks the lateral relative position of another set of upper and lower gratings at this time, that is, the position where the slope of the gentle reflected light intensity curve is the largest, that is, the position where the detector sensitivity is the highest, The magnitude of the acceleration is calculated through the feedback current of the comb electrodes. The present invention greatly reduces the volume of the system, and introduces comb electrodes and capacitive plates as electrostatic force recovery closed-loop devices, which can accurately detect acceleration and expand the dynamic range of the detector; the pulsed light intensity generated by a group of gratings Change the signal to lock the position of the maximum slope of the gentle light intensity change signal generated by another group of gratings, so as to measure the acceleration; realize the miniaturization and high precision of the sensing system, and have a wide range of application prospects in the aviation and military fields.

Description of drawings

Fig. 1 is the overall structure schematic diagram of the combined grating micromachined acceleration sensor of the present invention;

Fig. 2 is the structural representation of upper strata capacitor plate;

Fig. 3 is the structural representation of lower floor capacitor plate;

Fig. 4 is the structural representation of light source and detector;

Figure 5 is a schematic diagram of the overall structure;

Fig. 6 is a partially enlarged view of a group of gratings in the four-group structure of the upper capacitive plate;

Fig. 7 is a partially enlarged view of a group of gratings in the structure of four groups of lower capacitor plates;

Figure 8 is a graph showing the pulsed change curve of the reflected light intensity as the upper and lower gratings move relative to each other when the grating interval is 300-400nm;

Figure 9 is a graph showing the gentle change of the reflected light intensity as the upper and lower gratings move relative to each other when the grating interval is 1000-1200 nm;

In the figure, the light source 1, the first moving grating 2, the first fixed grating 3, the antireflection layer 4, the first infrared photodetector 5, the first focusing lens group 6, the second infrared photodetector 7, and the second focusing lens Group 8, first fixed base 9, return-shaped cantilever beam 10, upper capacitor plate 11, lower capacitor plate 12, signal processing module 13, current drive module 14, second fixed base 15, beam splitter 16, first comb An electrode 17 , a second comb electrode 18 , a second moving grating 20 , a second fixed grating 21 , and a proof mass region 22 .

Detailed ways

The present invention will be described in further detail below in conjunction with the accompanying drawings.

When the TE polarized 1530nm infrared light source is irradiated vertically on the sub-wavelength grating, it will propagate in the form of evanescent waves on the surface of the grating. When the two gratings are very close in the vertical direction, the light will oscillate between the two gratings, the light will pass from one grating to the other through the evanescent field, and the evanescent wave of the other grating will also pass through the evanescent field Coupling will be the original grating. When the two layers of gratings are laterally displaced due to the traction of the mass block by the acceleration, the resonance field will change, and the intensity of the reflected light will increase sharply. By detecting the change in the intensity of the reflected light, we can accurately know the horizontal and vertical Relative displacement, so as to know the magnitude of the input acceleration. By adjusting the longitudinal interval of the two layers of gratings, two kinds of reflected light intensity changes can be produced, one is a gentle change curve of light intensity relative to displacement, and the other is a pulsed change curve of light intensity relative to displacement. Utilizing the extremely narrow line width of the pulse-like change curve, the comb-shaped electrode can lock the position where the slope of the gentle change curve is the largest, so that the magnitude of the acceleration can be calculated by using the feedback current.

As shown in Figures 1-7, a combined grating micromechanical acceleration sensor of the present invention includes four sets of transmitting and receiving devices, an enhancement layer 4, a first fixed base 9, a second fixed base 15, a circular cantilever beam 10, an upper layer Capacitance plate 11, lower floor capacitor plate 12, signal processing module 13 and current drive module 14; One end of described upper layer capacitor plate 11 is connected with first fixed base 9, and the other end is connected with second fixed base 15; Upper layer capacitor plate 11 A proof mass area 22 is provided in the middle; a curved cantilever beam 10 is etched on the left and right sides of the mass area 22, and a T-shaped grating area connected to the mass area 22 is respectively provided at the upper and lower ends of the mass area 22. On the upper capacitor plate 11 A channel is etched around the mass block area 22 and the T-shaped grating area; the channel has a comb-like structure on the four corners of the mass block area 22, and the comb-shaped teeth formed by the comb-like structure in the mass block area serve as the first comb-shaped electrode 17 , the comb teeth paired with the first comb electrode 17 serve as the second comb electrode 18 , and the second comb electrode 18 is attracted or repelled by the first comb electrode 17 by electrostatic force.

The two side edges of the top surface of the T-shaped grating area have downward rectangular grooves, and the groove depth of the groove is 600-900nm, and the second moving grating 20 is etched on the groove, and in the T-shaped grating area The first moving grating 2 with the same structure as the second moving grating 20 is symmetrically etched inside the top surface; the first fixed base 9 and the second fixed base 15 are both fixed on the anti-reflection layer 4 and electrically connected with the anti-reflection layer 4 .

The first fixed grating 3 with the same structure as the first movable grating 2 is etched at the position corresponding to the four first moving gratings 2 of the upper layer capacitor flat plate 11 on the lower capacitor plate 12, which is similar to the four second movable gratings 20. The corresponding position is etched with the second fixed grating 21 having the same structure as the second moving grating 20; the distance between the initial position of the first fixed grating 3 and the initial position of the first moving grating 2 in the direction perpendicular to the grating is 295-305nm; the distance between the horizontal initial position of the second fixed grating 21 and the lateral initial position of the second moving grating 20 in the direction perpendicular to the grating is 163-167nm; the lower capacitor plate 12 is fixed on the antireflection layer 4, Insulated from the anti-reflection layer 4.

Each group of transmitting and receiving devices includes two groups of transmitting receivers, and each group of transmitting and receiving devices includes a light source 1, a beam splitter 16, a first infrared photodetector 5, a first focusing lens group 6, a second infrared photodetector device 7 and second focusing lens group 8; the two light sources 1 of each group of transmitting and receiving devices are respectively placed directly above the first moving grating 2 and the second moving grating 20 of the upper capacitive plate 11, and a splitter is arranged below the light source 1 Beamer 16, the first infrared photodetector 5 and the second infrared photodetector 7 are symmetrically placed on both sides of the light source 1, the first focusing lens group 6 is placed directly below the first infrared photodetector 5, and the second focusing The lens group 8 is placed directly below the second infrared photodetector 7; eight first infrared photodetectors 5 and eight second infrared photodetectors 7 are all connected to the signal processing module 13; The current drive module 14 is connected after being connected by leads; the two sides of the AR layer 4 are connected by leads and then connected to the current drive module 14 ;

The light source 1 is an infrared 1530nm light source with collimated beam expansion; the antireflection layer 4 is formed by sequentially coating 600nm SiO ₂ and 800nm Si ₃ N ₄ on a Si substrate.

The thicknesses of the first moving grating 2, the second moving grating 20, the first fixed grating 3 and the second fixed grating 21 are all 950-965nm, the number of gratings is 30-80, and the period T is 1493-1500nm. The duty cycle is 0.45-0.5; the air gap between the first moving grating 2 and the first fixed grating 3 is 300-400nm; the air gap between the second moving grating 20 and the second fixed grating 21 is 1000nm-1200nm.

A method for measuring acceleration using the above-mentioned combined grating micromachined acceleration sensor, comprising the following steps:

The light emitted by the two light sources 1 of each group of transmitting and receiving devices passes through the beam splitter 16 to generate two laser beams, wherein, one laser beam from the two light sources 1 is irradiated to the area of the upper capacitor plate 11 without a grating and then reflected, and the reflected beam passes through The first focusing lens group 6 is irradiated onto the first infrared photodetector 5; the other laser light of one light source passes through the first moving grating 2 of the upper capacitive plate 11, the first fixed grating 3 of the lower capacitive plate 12, and the anti-reflection layer After 4, the light beam reflected by the antireflection layer 4 is irradiated on the second infrared photodetector 7 through the second focusing lens group 8; another laser light from another light source passes through the second moving grating 20 of the upper capacitor plate 11, the lower layer After the second fixed grating 21 and the anti-reflection layer 4 of the capacitor plate 12, the light beam reflected by the anti-reflection layer 4 is irradiated onto the second infrared photodetector 7 through the second focusing lens group 8;

The light intensity signals received on the two first infrared photodetectors 5 and the two second infrared photodetectors 7 of each group of transmitting and receiving devices are sent to the signal processing module 13 for comparison and analysis, and the noise is filtered out by differential technology to obtain a general Wood abnormal gentle light intensity change signal and special Wood abnormal pulsed light intensity change signal; the current drive module 14 outputs current to the upper capacitor plate 11 and the lower capacitor plate 12, and adjust the vertical distance between the two capacitor plates by adjusting the magnitude of the current. Thereby obtaining the special Wood anomaly pulsed light intensity change signal with different line widths, when the line width of the obtained pulsed light intensity change signal is the narrowest, lock the current given to the capacitor plate at this time; when the upper layer capacitor plate 11 and the lower layer capacitor plate 12 Due to the lateral relative displacement of the traction of the mass block 22 by the acceleration, a general Wood anomaly gentle light intensity change signal and a special Wood anomaly pulse light intensity change signal are generated, and the adjustment is provided to the first comb-shaped electrode 17 and the second comb-shaped electrode 18 current, so that the lateral relative position of the first moving grating 2 and the first fixed grating 20 is maintained at the position where the slope of the gentle light intensity change curve is the largest, and this position is to simultaneously make the second moving grating 3 and the second fixed grating 21 generate a pulse pattern The relative position of the peak value of the light intensity signal uses the extremely narrow line width of the pulse to lock the current given to the comb electrode at this time, which is recorded as the horizontal initial position, that is, the position where the slope of the gentle light intensity change curve is locked; when the upper capacitor plate 11 and When the lower capacitive plate 12 is displaced laterally due to the pull of the mass block 22 by the acceleration, the first comb-shaped electrode 17 and the second comb-shaped electrode 18 are driven by the current drive module 14, and the moving grating is pulled back to the locked lateral initial position , calculate the output current, and calculate the input acceleration size according to the elastic coefficient of the cantilever beam and the quality of the mass block; to the signals collected by eight first infrared photodetectors 5 and eight second infrared photodetectors 7 The four groups of accelerations obtained by the analysis are averaged to obtain the final acceleration; if the interval between the upper capacitor plate 11 and the lower capacitor plate 12 changes due to external vibrations, the pulse signal disappears, and the current drive module 14 adjusts the output again current until the pulsed light intensity signal reappears.

The manufacturing method of the combined grating micromachined acceleration sensor of the present invention comprises the following steps:

1. The light source 1 adopted in the example of the present invention is from Wuhan Telecom Devices Co., Ltd. (WTD), with a power of 1-10mW and a wavelength of 1530nm, driven by a constant power circuit. After the light source 1 passes through the infrared band collimator of Thorlab, the If the divergence angle is less than 1 degree, adjust the distance between the light source 1 and the surface of the moving grating 2 so that the spot size matches the grating area; the first infrared photodetector 5 and the second infrared photodetector 7 use photomultiplier tubes.

2. Take a 150mm-diameter Si substrate surface to clean, do n-type doping on it, and oxidize it by traditional wet method at 1050°C for 1.5 hours in a high temperature environment, and oxidize a layer of SiO ₂ film on it , film thickness is 600nm. Then 800nm Si ₃ N ₄ is deposited on SiO ₂ by LPCVD technique at a temperature of 850°C. Then use reactive ion beam etching to etch an opening in the SiO ₂ and Si ₃ N ₄ layer, which is used to fix the first fixed base 9 and the second fixed base 15, so that the current can be conducted from the base, control The spacing between the two raster layers.

3. Next, deposit a 960nm Si film on the surface of Si ₃ N ₄ by LPCVD at 580 degrees Celsius. The thickness of this layer of Si has a higher requirement and needs to be completed through two depositions. For the first time, about 800nm of Si is deposited, and for the second time, the deposition rate is reduced, and N-type doped Si is used for deposition, while chemical mechanical polishing is used to polish the surface of the silicon layer, so that the silicon layer reaches an accurate thickness of 960nm. Next, a mask is attached on the surface of the evaporated Si layer, and four sets of first fixed gratings 3 and four sets of second fixed gratings 21 are etched by using 248nm ultraviolet lithography technology and reactive ion beam etching technology. The number of grating lines of the first fixed grating 3 and the second fixed grating 21 is 30-80.

4. Then deposit a layer of 1.2um SiO ₂ on the Si surface as a sacrificial layer to create an air gap between the upper and lower layers of the grating, and use CMP technology to smooth the surface, and then attach a mask to etch the upper capacitor plate 11. The space required for the downward rectangular groove. After completion, deposit a 960nm Si film on the surface of _SiO2 by depositing the first fixed grating 3 and the second fixed grating 21 again, so that the silicon layer reaches an accurate thickness of 960nm, and at the same time use chemical mechanical polishing to polish the surface of the silicon layer. Next, a mask is used to etch the proof-mass region 22 , the return-shaped cantilever beam 10 , the first comb-shaped electrodes 17 , the second comb-shaped electrodes 18 , four groups of first moving gratings 2 and four groups of second moving gratings 20 .

5. Finally, deposit a 0.5um SiO ₂ sacrificial layer to wrap the anti-reflection layer 4 and the various parts of the grating, because the device needs to be deposited on the moving grating 2 with N-type impurities at a high temperature of 1100 degrees Celsius, so as to Release the stress of the Si material. Afterwards, the device was immersed in HF solution to sacrifice the _SiO2 layer to form a gap between the two grating layers, then rinsed with deionized water and zero-point dried with _CO2 . Then the device is packaged and connected to the current driving module 14 .

Two layers of sub-wavelength gratings of the present invention are combined to form a resonant cavity, the first layer of grating is a movable part, the second layer of grating is a fixed part, and the relative displacement between the movable part and the fixed part due to the traction of the mass block by acceleration can be Affecting the propagation modes of the incident light inside the grating, they are the leakage mode and the conduction mode, resulting in changes in the reflected light intensity of the grating. Adjusting the longitudinal interval of the two layers of gratings can produce different forms of light intensity change curves. It can be seen from Fig. 8 that in the present invention, when the relative longitudinal interval is 300-400 nm, the curve will produce a pulse shape, and when the relative lateral displacement is 163-167 nm, the pulse will reach a peak. It can be seen from Fig. 9 that in the present invention, when the relative longitudinal distance is 1000-1200 nm, the curve will be gentler, and when the relative lateral displacement is 295-305 nm, the curve reaches its maximum slope position. By rationally adjusting the initial relative positions of the two groups of gratings, when the two layers of gratings move to a certain position, the pulse reaches its peak value and the curve reaches its maximum slope, so that the extremely narrow line width of the pulse is used to lock the maximum slope position , so as to achieve accurate measurement of acceleration.

Claims (3)

1. a combination grating micro-machine acceleration transducer, it is characterized in that, comprise four groups of sending and receiving apparatus, increase anti-layer (4), the first firm banking (9), the second firm banking (15), back-shaped semi-girder (10), upper strata electric capacity flat board (11), lower floor's electric capacity flat board (12), signal processing module (13) and electric current driver module (14); One end of described upper strata electric capacity flat board (11) is connected with the first firm banking (9), and the other end is connected with the second firm banking (15); The middle on upper strata electric capacity flat board (11) is provided with mass region (22); Back-shaped semi-girder (10) is etched in the left and right sides of mass region (22), upper and lower two ends are respectively provided with a T-shaped grating region be connected with mass region (22), around mass region (22) and T-shaped grating region etched channels on upper strata electric capacity flat board (11); Described passage has pectination on four angles of mass region (22), the comb teeth that pectination is formed in mass region is as the first comb electrode (17), the comb teeth of matching with the first comb electrode (17) is as the second comb electrode (18), and described second comb electrode (18) is attracted or repulsion by the first comb electrode (17) by electrostatic force;

The both sides of the edge of described T-shaped grating region end face have downward rectangular recess, the groove depth of described groove is 600-900nm, groove etches the second moving grating (20), the first moving grating (2) that the inside top surface symmetry etching in T-shaped grating region is identical with the second moving grating (20) structure; First firm banking (9) and the second firm banking (15) are all fixed on and increase on anti-layer (4) and be electrically connected with the anti-layer of increasing (4);

The upper position corresponding with four first moving gratings (2) on upper strata electric capacity flat board (11) of described lower floor's electric capacity flat board (12) etches first fixed grating (3) identical with the first moving grating (2) structure, and the position corresponding with four the second moving gratings (20) etches second fixed grating (21) identical with the second moving grating (20) structure; The horizontal initial position of described first fixed grating (3) and the horizontal initial position of the first moving grating (2) are being 295-305nm perpendicular to the distance on grating orientation; The horizontal initial position of described second fixed grating (21) and the horizontal initial position of the second moving grating (20) are being 163-167nm perpendicular to the distance on grating orientation; Lower floor's electric capacity flat board (12) is fixed on and increases on anti-layer (4), insulate with the anti-layer of increasing (4);

Described sending and receiving apparatus of often organizing comprises two groups of transceivers, and described transceiver of often organizing comprises light source (1), beam splitter (16), the first infrared photoelectric detector (5), the first focus lens group (6), the second infrared photoelectric detector (7) and the second focus lens group (8); Directly over the first moving grating (2) that two light sources (1) often organizing sending and receiving apparatus are placed in upper strata electric capacity flat board (11) respectively and the second moving grating (20), the below of light source (1) is provided with beam splitter (16), first infrared photoelectric detector (5) and the second infrared photoelectric detector (7) are symmetrically placed in the both sides of light source (1), first focus lens group (6) is placed in immediately below the first infrared photoelectric detector (5), and the second focus lens group (8) is placed in immediately below the second infrared photoelectric detector (7); Eight the first infrared photoelectric detectors (5) are all connected with signal processing module (13) with eight the second infrared photoelectric detectors (7); The both sides of lower floor's electric capacity flat board (12) are by connected rear access electric current driver module (14) of lead-in wire; Increase the both sides of anti-layer (4) by connected rear access electric current driver module (14) of lead-in wire; Electric current driver module (14) is connected with signal processing module (13);

Described light source (1) is the infrared 1530nm light source with collimator and extender; The anti-layer of described increasing (4) is by SiO Si substrate being coated with successively 600nm ₂with the Si of 800nm ₃n ₄formed;

The thickness of described first moving grating (2), the second moving grating (20), the first fixed grating (3) and the second fixed grating (21) is 950-965nm, and raster count is 30-80, and cycle T is 1493-1500nm, and dutycycle is 0.45-0.5; The clearance of the first moving grating (2) and the first fixed grating (3) is 300-400nm; Second moving grating (20) is 1000nm-1200nm with the clearance of the second fixed grating (21).

2. combine grating micro-machine acceleration transducer according to claim 1, it is characterized in that: described light source (1) is Vcsel.

3. utilize the method combining grating micro-machine acceleration transducer acceleration measurement described in claim 1, it is characterized in that, comprise the following steps:

The light that two light sources (1) often organizing sending and receiving apparatus send all produces two-way laser by beam splitter (16), wherein, one road laser of two light sources (1) is all irradiated to the region back reflection that upper strata electric capacity flat board (11) does not have grating, and folded light beam is irradiated on the first infrared photoelectric detector (5) by the first focus lens group (6); Another road laser of a light source is successively by after first moving grating (2) on upper strata electric capacity flat board (11), first fixed grating (3) of lower floor's electric capacity flat board (12) and the anti-floor of increasing (4), and the light beam reflected through increasing anti-layer (4) is irradiated on the second infrared photoelectric detector (7) by the second focus lens group (8); Another road laser of another light source is successively by after second moving grating (20) on upper strata electric capacity flat board (11), second fixed grating (21) of lower floor's electric capacity flat board (12) and the anti-floor of increasing (4), and the light beam reflected through increasing anti-layer (4) is irradiated on the second infrared photoelectric detector (7) by the second focus lens group (8);

Often organize the light intensity signal that two the first infrared photoelectric detectors (5) of sending and receiving apparatus and two the second infrared photoelectric detectors (7) receive to be sent to signal processing module (13) and to be analyzed, obtain the abnormal mild light intensity variable signal of general Wood and special Wood abnormal pulsers formula light intensity variable signal by differential technique filtering noise, electric current driver module (14) output current is to upper strata electric capacity flat board (11) and lower floor's electric capacity flat board (12), the longitudinal separation of two-layer electric capacity flat board is adjusted by the size adjusting electric current, thus obtain the different special Wood abnormal pulsers formula light intensity variable signal of live width, when the live width of the pulsed light intensity variable signal obtained is the narrowest, locking now gives the electric current of electric capacity flat board, when upper strata electric capacity flat board (11) and lower floor's electric capacity flat board (12) are owing to producing the abnormal mild light intensity variable signal of general Wood and special Wood abnormal pulsers formula light intensity variable signal when horizontal relative displacement occurs in the traction of acceleration to mass (22), adjustment is supplied to the electric current of the first comb electrode (17) and the second comb electrode (18), the first moving grating (2) and the first fixed grating (20) horizontal relative position is made to remain on the maximum position of mild light intensity curve slope, this position is the relative position simultaneously making the second moving grating (3) and the second fixed grating (21) produce pulsed light intensity signal peak value, utilize the pole narrow linewidth of pulse, locking now gives the electric current of comb electrode, be designated as horizontal initial position, namely the position that mild light intensity curve slope is maximum is locked, when again there is horizontal relative displacement due to the traction of acceleration to mass (22) in upper strata electric capacity flat board (11) and lower floor's electric capacity flat board (12), the first comb electrode (17) and the second comb electrode (18) is driven by electric current driver module (14), moving grating is withdrawn into the horizontal initial position of locking, calculate the electric current exported, according to the elasticity coefficient of back-shaped semi-girder and the quality of mass, calculate the acceleration magnitude of input, four groups of acceleration magnitude that the signal analysis gathered eight the first infrared photoelectric detectors (5) and eight the second infrared photoelectric detectors (7) obtains are averaged, and obtain final acceleration, if the reason due to external shock causes the interval variation between upper strata electric capacity flat board (11) and lower floor's electric capacity flat board (12), pulse signal is disappeared, electric current driver module (14) adjusts output current again, until reappear pulsed light intensity signal.