CN101290215B - Micro-displacement sensor based on PGC demodulated interferential scanning - Google Patents

Abstract

The invention discloses a micro displacement sensor based on PGC demodulation interferometric scanning. The micro displacement sensor comprises grating interference, interference optical path difference demodulation and signal processing, wherein the grating interference part comprises an optical source, a sine amplitude grating, a beam splitter prism and a reflector, is based on the grating interference principle and perceives the displacement information of the grating through interference fringe. The interference optical path difference demodulation part comprises four blocks of micro lenses and a piezoelectric vibrator, is arranged on -1 level (or +1 level) optical path to perform PGC demodulation on interference signals. The signal processing part comprises a photoelectric converter, a signal amplifier and a signal processing circuit and performs PGC demodulation on interference signals to obtain displacement information. The micro distance sensor has the advantage of a big dynamic scope as a strip grating interference displacement measuring device, the measuring precision is greatly improved and the resolution is up to the nanometer level after PGC and PGC demodulation technique are introduced.

Description

A kind of micro-displacement sensor based on the PGC demodulated interferential scanning

Technical field

The present invention relates to the micro-displacement sensor field, particularly a kind of high resolving power, great dynamic range based on the micro-displacement sensor of PGC demodulated interferential scanning.

Background technology

Sensor is a kind of preposition parts in the measuring system, and external physical quantity or chemistry amount that it can't be handled electronic system are converted to usable output signal, to reach the measurement purpose or to be that post-processed provides information.In the flourishing advanced information society of science and technology, sensor has been widely used in fields such as industry, agricultural, environmental protection, transportation and national defence.

Under the powerful expulsive force of social demand, sensor is just experiencing develop rapidly period.The miniaturization of moment sensor technology forward, integrated development to digitizing, intelligent development, progressively turn to the photoelectron sensing by electronic sensor on principle of work, improve sensing sensitivity apace, and have become the key content of 21 century countries in the world development.

Micro-displacement sensor is one of most basic assembly in numerous sensors, many other physics, and the sensing of chemistry or biomass is all based on displacement sensing.For example acceleration transducer is the important member of sensor family, be used for the device of Measuring Object acceleration of motion, and had ripe market, low precision product has been widely used in as safe automobile air bag, and what its module was used mainly is the acceleration transducer of 50g dynamic range; Acceleration transducer market expands to the application facet of the industry and the consumer goods from the auto manufacturing market on basis simultaneously.Yet on principle, most accelerometers all record acceleration indirectly by Displacement Measurement (angular displacement or displacement of the lines).Thereby the research displacement transducer has very important meaning to the exploitation acceleration transducer.

At present the method for Displacement Measurement has a lot, such as utilizing the moire fringe displacement sensor, and the single-grating interferometer on the present market etc.But there are some problems in they, and are not high enough such as precision, and dynamic range is big inadequately, and volume is bigger etc.And the application need high sensitivity of most of smart machines, high resolving power and great dynamic range displacement transducer, and require to have the micro-structure size.This makes us will seek a kind of new have small size, high sensitivity, the micro-displacement sensor of high resolving power and great dynamic range.

Summary of the invention

The object of the present invention is to provide a kind of micro-displacement sensor based on the PGC demodulated interferential scanning, (phase generated carrier, PGC) technology have that volume is little, resolution is greater than 10 to have utilized grating interference principle and phase generated carrier demodulation ⁶, highly sensitive in nanoscale, the outstanding advantage of the unrestricted grade of dynamic range.

The technical solution adopted for the present invention to solve the technical problems is:

Scheme one:

Form by grating interference, the modulation of interference light path difference and three parts of signal Processing; Wherein:

1) grating interference part: comprise laser diode, sinusoidal amplitude gratings strips, Amici prism and catoptron; The sinusoidal amplitude gratings strips is vertical with the optical axis of LASER Light Source; Amici prism is on grade light path of optical grating diffraction+1, and light splitting surface becomes miter angle with+1 grade of light path, and light splitting surface is parallel with the grating grid line; Catoptron is in interference light path difference modulating part back, and the minute surface of catoptron is parallel with the grating grid line, and makes-1 grade of light reflection back become miter angle with the light splitting surface of Amici prism;

2) interference light path difference modulating part is on-1 grade of light path, and does not change the direction of propagation of-1 grade of light;

3) signal processing: comprise photoelectric commutator, signal amplifier and signal processing circuit; Photoelectric commutator receives interference signal after being arranged on Amici prism with optical axis, and its output terminal is connected with signal processing circuit with signal amplifier.

Scheme two:

Form by grating interference, the modulation of interference light path difference and three parts of signal Processing; Wherein:

1) grating interference part: comprise laser diode, sinusoidal amplitude gratings strips, Amici prism and catoptron; The sinusoidal amplitude gratings strips is vertical with the optical axis of LASER Light Source; Amici prism is in interference light path difference modulating part (6) back, and light splitting surface becomes miter angle with+1 grade of light path, and light splitting surface is parallel with the grating grid line; Catoptron is on-1 grade of light path, and the minute surface of catoptron is parallel with the grating grid line, and makes-1 grade of light reflection back become miter angle with the light splitting surface of Amici prism;

2) interference light path difference modulating part be in+1 grade of light path on; And do not change+direction of propagation of 1 grade of light;

3) signal processing: comprise photoelectric commutator, signal amplifier and signal processing circuit; Photoelectric commutator receives interference signal after being arranged on Amici prism with optical axis, and its output terminal is connected with signal processing circuit with signal amplifier.

More than a kind of interference light path difference modulating part described in two kinds of schemes comprise four eyeglasses, two pedestals, piezoelectric ceramics Vib. and modulation signal generators; First eyeglass and the 4th eyeglass are separately fixed at 90 of first pedestal and spend on two faces of corner angle, second eyeglass and prismatic glasses are separately fixed at 90 of second pedestal and spend on two faces of V-type grooves, second base bottom surface is fixed on the vibration plane of piezoelectric ceramics Vib., the corner angle of first pedestal do not overlap with the second pedestal V-type groove, and the piezoelectric ceramics Vib. is driven by modulation signal generator.

More than the another kind of interference light path difference modulating part described in two kinds of schemes comprise four eyeglasses, two pedestals, piezoelectric ceramics Vib. and modulation signal generators; First eyeglass and the 4th eyeglass are separately fixed at 90 of first pedestal and spend on two faces of corner angle, second eyeglass and prismatic glasses are separately fixed at 90 of second pedestal and spend on two faces of V-type grooves, first base bottom surface is fixed on the vibration plane of piezoelectric ceramics Vib., the corner angle of first pedestal do not overlap with the second pedestal V-type groove, and the piezoelectric ceramics Vib. is driven by modulation signal generator.

Be example with scheme one now: the present invention is based on the grating interference principle, by interference fringe perceived light grizzly bar displacement information, is the essential part that native system is realized micro-displacement sensing.Interference light path difference modulating part is made up of four microreflection eyeglass and Vib.s of installing by ad hoc structure.It obtains the phase information of interference signal based on phase generated carrier (PGC) principle, the details between the long mutually and destructive interference basis signal of distinguishable grating interference part, thus realization increases substantially the resolution of grating interference.Signal processing is made up of photoelectric commutator, signal amplifier and signal processing circuit, and this part is carried out the PGC demodulation to interference signal, obtains displacement information.

The principle of work of grating interference part is: laser vertical incides the sinusoidal amplitude gratings strips, forms+1 grade and-1 grade of two bundle diffraction light after the optical grating diffraction beam split; Adopt a catoptron and an Amici prism that this two bundles diffraction light is converged to produce and interfere, form interference fringe; When gratings strips in grating planar when moving with the grid line vertical direction, cause the interference fringe corresponding mobile; By the counting and the segmentation of interference fringe, can obtain the information of pattern displacement amount.

Suppose laser beam after the optical grating diffraction beam split+1 order diffraction light can be expressed as:

E ₊₁＝E ₀·cos(ωt+kz ₊₁)

-1 order diffraction light can be expressed as:

E _-1＝E ₀·cos(ωt+kz _-1)

E in the formula ₀For interfering the amplitude of time ± 1 grade light, because two-beam interferes time ± 1 a grade light amplitude to be more or less the same, the fine difference of amplitude is little to the influence of result of calculation, thinks that their amplitude all is E so can be similar to ₀ω is the angular frequency of light source; z _{+ 1}And z _-1Be ± 1 grade of light light path of process separately, t is the time, and k is the Space Angle frequency.

When gratings strips in grating planar along moving x with the grid line vertical direction ₀The time,

$E_{+1}=E_0\·\cos (\mathrm{\ωt}+{\mathrm{kz}}_{+1}-2\mathrm{\π}\frac{x_0}{d})$

$E_{-1}=E_0\·\cos (\mathrm{\ωt}+{\mathrm{kz}}_{-1}+2\mathrm{\π}\frac{x_0}{d})$

$E_{+1}+E_{-1}=2E_0\·\cos (\mathrm{\ωt}+k\frac{z_{+1}+z_{-1}}{2})\·\cos (k\frac{z_{-1}-z_{+1}}{2}+2\mathrm{\π}\frac{x_0}{d})$

$=E_0^{\′}\·\cos (k\frac{z_{-1}-z_{+1}}{2}+2\mathrm{\π}\frac{x_0}{d})$

D is the grating constant of gratings strips in the formula.The result shows that interference signal has comprised pattern displacement information x ₀

The principle of work of interference light path difference modulating part (first kind of embodiment) is: this part and is on-1 grade of light path between sinusoidal amplitude gratings strips and catoptron, and right-1 grade of light phase is modulated.-1 grade of light is mapped on first eyeglass 6.1 with 45 degree incident angles, be mapped on second eyeglass 6.2 with 45 degree incident angles after reflection, the light that reflects from second eyeglass 6.2 is mapped to prismatic glasses 6.3 with 45 degree incident angles once more, be mapped on the 4th eyeglass 6.4 with 45 degree incident angles once more after reflection, penetrate from the 4th eyeglass 6.4 with 45 degree emergence angle at last.Because the special construction of lens set is from the light and the light conllinear that incides first eyeglass 6.1 of the 4th eyeglass 6.4 outgoing.

When piezoelectric ceramics (PZT) Vib. vibrated with sinusoidal rule, the change in optical path length of-1 grade of light introducing was:

Δ＝2A·sin(ω′t)

Wherein A and ω ' are respectively piezoelectric ceramics (PZT) Vib. amplitude and vibration frequency.

-1 grade of light after the modulation becomes:

$E_{-1}=E_0\·\cos [\mathrm{\ωt}+{\mathrm{kz}}_{-1}+2\mathrm{\π}\frac{x_0}{d}+2\mathrm{kA}\sin \left({\mathrm{\ω}}^{\′}t\right)]$

Interference signal becomes:

$E\left(x_0\right)=E_{+1}+E_{-1}=E_0^{\′\′}\·\cos [k\frac{z_{-1}-z_{+1}}{2}+2\mathrm{\π}\frac{x_0}{d}+\mathrm{kA}\·\sin \left({\mathrm{\ω}}^{\′}t\right)]$

Wherein, $E_0^{\′\′}=2E_0\·\cos [\mathrm{\ωt}+k\frac{z_{+1}+z_{-1}}{2}+\mathrm{kA}\·\sin \left({\mathrm{\ω}}^{\′}t\right)],$

Be the phase place of original interference signal, (ω ' t) is a modulation signal to ASin.

Interference signal E (x ₀) be actually a phase-modulation wave, utilize phase generated carrier (PGC) demodulation techniques that this phase-modulation wave is carried out demodulation, just can obtain the extremely high phase information of precision, the x of pattern displacement information just ₀Typical phase generated carrier demodulation method has: homodyne demodulation method (Homodyne demodulation), pseudo-heterodyne demodulation method (Pseudo-heterodyne demodulation), synthetic heterodyne demodulation method (Synthetic-heterodyne demodulation) and reference sensor method etc.Utilize these demodulation methods just can obtain the phase information of interference signal, thereby improve the resolution that grating interference is measured.

Signal processing is based on phase generated carrier (PGC) demodulation principle.Photoelectric commutator is one the photodiode of diaphragm to be housed, and diaphragm has minimum aperture (about 0.1mm diameter), is used to receive the interference signal from the Amici prism outgoing; Photodiode changes interference signal into electric signal, and electric signal is connected to signal processing circuit through signal amplifier; Signal processing circuit designs based on phase generated carrier (PGC) demodulation principle.Like this, the phase information of interference signal just can be come out by the signal processing circuit demodulation.

The beneficial effect that the present invention has is:

1) the present invention adopts the grating interference principle to form basic structure, and simple in structure, gratings strips is unrestricted on its length direction, thereby greatly improves the dynamic range of this micro-displacement sensor.

2) the present invention adopts laser diode as light source, need not just can carry out the grating interference sensing through expanding bundle.Spot size is minimum, so gratings strips lateral dimension (with perpendicular direction to be measured) can be very little, for example can be as small as about 2-5mm.Other elements, eyeglass for example, reflective mirrors etc. can use device or the integrated small components of optics bore as 2-5mm, thus reduction system volume greatly.In addition, native system can be packaged into small module, and it is little to have structure, and stable performance is easy to use, advantages such as highly versatile.

3) the present invention proposes the phase modulation (PM) structure that four miniature eyeglasses are formed, and realizes not changing the optical path modulation under the light path condition, has realized phase generated carrier (PGC) technology with new form.Thereby can on the basis of grating interference resolution, increase substantially the resolution of displacement transducer, make it bring up to or surpass nanometer scale from hundreds of nanometers.And its dynamic range, promptly the movable scope of gratings strips is then unrestricted, can use technically as flexible grating band and realize long distance, high-precision measurement.

Description of drawings

Fig. 1 is based on first kind of embodiment principle schematic of the micro-displacement sensor of PGC demodulated interferential scanning;

Fig. 2 is first kind of example structure synoptic diagram of interference light path difference modulating part;

Fig. 3 is phase generated carrier (PGC) principle schematic;

Fig. 4 is based on second kind of embodiment principle schematic of the micro-displacement sensor of PGC demodulated interferential scanning;

Fig. 5 is second kind of example structure synoptic diagram of interference light path difference modulating part.

Among the figure: 1, laser diode, 2, the sinusoidal amplitude gratings strips, 3, Amici prism, 4, photoelectric commutator, 5, signal amplifier and signal processing circuit, 6, interference light path difference modulating part, 6.1, eyeglass, 6.2, eyeglass, 6.3, eyeglass, 6.4, eyeglass, 6.5, pedestal, 6.6, pedestal, 6.7, the piezoelectric ceramics Vib., 7, catoptron

Embodiment

As shown in Figure 1, a kind of micro-displacement sensor based on the PGC demodulated interferential scanning of the present invention is made up of grating interference, the modulation of interference light path difference and three parts of signal Processing; Wherein:

1) grating interference part: comprise laser diode 1, sinusoidal amplitude gratings strips 2, Amici prism 3 and catoptron 7; Sinusoidal amplitude gratings strips 2 is vertical with the optical axis of LASER Light Source; Amici prism 3 is on grade light path of optical grating diffraction+1, and light splitting surface becomes miter angle with+1 grade of light path, and light splitting surface is parallel with the grating grid line; Catoptron 7 is in interference light path difference modulating part 6 back, and the minute surface of catoptron 7 is parallel with the grating grid line, and makes-1 grade of light reflection back become miter angle with the light splitting surface of Amici prism 3;

2) interference light path difference modulating part 6 is on-1 grade of light path, and does not change the direction of propagation of-1 grade of light;

As Fig. 2, shown in Figure 3, described interference light path difference modulating part 6 comprises 6.1,6.4,6.2,6.3, two pedestals 6.5,6.6 of four eyeglasses, piezoelectric ceramics Vib. 6.7 and modulation signal generator 6.8; First eyeglass 6.1 and the 4th eyeglass 6.4 are separately fixed at 90 of first pedestal 6.5 and spend on two faces of corner angle, second eyeglass 6.2 and prismatic glasses 6.3 are separately fixed at 90 of second pedestal 6.6 and spend on two faces of V-type grooves, second pedestal, 6.6 bottom surfaces are fixed on the vibration plane of piezoelectric ceramics Vib. 6.7, the corner angle of first pedestal 6.5 do not overlap with the second pedestal 6.6V type groove, and piezoelectric ceramics Vib. 6.7 is driven by modulation signal generator 6.8.Pedestal 6.5 is fixed on the light path of-1 grade of light, makes the minute surface of first eyeglass 6.1 and the 4th eyeglass 6.4 parallel with the grating grid line respectively, and makes-1 grade of light become miter angle with the minute surface of first eyeglass 6.1; The minute surface of first eyeglass 6.1 and second eyeglass 6.2 is parallel to each other, separately be spaced apart 1～3mm, the minute surface of prismatic glasses 6.3 and the 4th eyeglass 6.4 is parallel to each other, interval separately also is 1～3mm, and first eyeglass 6.1 overlaps with the equidistant point of dihedral angle that prismatic glasses 6.3 becomes with second eyeglass 6.2 with the equidistant point of the 4th dihedral angle that eyeglass 6.4 becomes.Plane, piezoelectric ceramics (PZT) Vib. 6.8 place all becomes miter angle with eyeglass 6.1,6.2,6.3,6.4.Piezoelectric ceramics (PZT) Vib. 6.8 vibrates on the vertical direction on its plane, place.Enter the light beam and the piezoelectric vibrator plane parallel of interference light path difference modulating part, with 6.1 one-tenth miter angles of first eyeglass; Penetrate the light beam and the piezoelectric vibrator plane parallel of interference light path difference modulating part, with 6.4 one-tenth miter angles of the 4th eyeglass, promptly interference light path difference modulating part does not change optical path direction.(in the time of the vibration of the rule of ω ' t), the light path of modulated light beam press 2Asin (the rule variation of ω ' t) when piezoelectric vibrator is pressed Asin.

As Fig. 3, shown in Figure 5, described interference light path difference modulating part 6 comprises 6.1,6.4,6.2,6.3, two pedestals 6.5,6.6 of four eyeglasses, piezoelectric ceramics Vib. 6.7 and modulation signal generator 6.8; First eyeglass 6.1 and the 4th eyeglass 6.4 are separately fixed at 90 of first pedestal 6.5 and spend on two faces of corner angle, second eyeglass 6.2 and prismatic glasses 6.3 are separately fixed at 90 of second pedestal 6.6 and spend on two faces of V-type grooves, first pedestal, 6.5 bottom surfaces are fixed on the vibration plane of piezoelectric ceramics Vib. 6.7, the corner angle of first pedestal 6.5 do not overlap with the second pedestal 6.6V type groove, and piezoelectric ceramics Vib. 6.7 is driven by modulation signal generator 6.8.The optical path modulation principle is similar to first kind of embodiment, and (in the time of the vibration of the rule of ω ' t), the light path of modulated light beam also is that (rule of ω ' t) changes by 2Asin when piezoelectric vibrator is pressed Asin.Two kinds of modulating part embodiment respectively have advantage, are suitable for different mounting structures respectively.

3) signal processing: comprise photoelectric commutator 4, signal amplifier and signal processing circuit 5, photoelectric commutator 4, signal amplifier and signal processing circuit 5 all can have been bought on market according to concrete needs; Photoelectric commutator 4 is arranged on Amici prism 3 backs with optical axis and receives interference signal, and its output terminal is connected with signal processing circuit 5 with signal amplifier.Photoelectric commutator receives interference signal, and its output terminal links to each other with signal processing circuit with signal amplifier.Photoelectric commutator is one to be encapsulated in the photodiode in the little magazine, and camera bellows has minimum aperture as diaphragm, is used to receive by Amici prism close the interference signal that bundle produces; Photodiode changes interference signal into electric signal, and electric signal is received signal amplifier and signal processing circuit; Signal amplifier and signal processing circuit have ready-made product based on the design of phase generated carrier (PGC) demodulation principle.

Laser beam impinges perpendicularly on the sinusoidal amplitude gratings strips 2, forms+1 grade and-1 grade of two bundle diffraction light behind a diffraction, and angle of diffraction is θ=λ/d, and wherein λ is laser instrument 1 wavelength, and d is a grating constant.+ 1 grade of light directly is mapped on the Amici prism 3.-1 grade of light enters interference light path difference modulating part 6 and is carried out phase modulation (PM), and (phase differential of ω ' t), wherein ω ' is the angular frequency of the modulation signal generator 6.8 that drives piezoelectric ceramics (PZT) Vib. 6.7 to introduce Δ=2Asin between+1 grade and-1 grade of light.Because the special construction of modulating part ,-1 grade of light is remained unchanged by the direction of propagation in this part modulated process, outgoing after catoptron 7 reflex on the another side of Amici prism 3.The position of accommodation reflex mirror 7 makes-1 grade of light after the reflection become miter angle with the light splitting surface of Amici prism 3, and-1 grade of light hot spot is overlapped on the light splitting surface of Amici prism 3 with+1 grade of light hot spot, regulates Amici prism 3 then, makes+1 grade and-1 grade of light conllinear.Through the bundle that closes of Amici prism 3 ,+1 grade and-1 grade of light formation interference.If sinusoidal amplitude gratings strips 2 does not move, because the effect of interference light path difference modulating part 6, the optical path difference between+1 grade and-1 grade of light changes by sinusoidal rule.

In the time of Displacement Measurement, displacement promotes sinusoidal amplitude gratings strips 2, and sinusoidal amplitude gratings strips 2 is moved along vertical grid line direction in grating planar.+ 1 grade therefore, and the optical path difference between-1 grade of light on the basis that changes by sinusoidal rule, introduce extra phase differential 4 π x ₀/ d, wherein, x ₀Be the displacement that promotes the sinusoidal amplitude gratings strips, d is a grating constant.If get the grating of 1000 lines/mm, side pitch d is 0.001mm, i.e. 1 μ m.The one-period number of sinusoidal voltage is represented the displacement of d/2, i.e. 500nm at this moment.With phase generated carrier demodulation (PGC) technology voltage signal is segmented, after system alignment and encapsulation, noise may be limited to lower level, like this can be with half period, and promptly 250nm (from the brightest to the darkest) is divided into 250 parts.Experiment confirm only uses common no DFB (Distributed feedback) laser diode can be easy to realize this decomposition, makes this transducer sensitivity surpass nanometer scale.

As shown in Figure 4, another kind of the present invention is made up of grating interference, the modulation of interference light path difference and three parts of signal Processing based on the micro-displacement sensor of PGC demodulated interferential scanning; Wherein:

1) grating interference part: comprise laser diode 1, sinusoidal amplitude gratings strips 2, Amici prism 3 and catoptron 7; Sinusoidal amplitude gratings strips 2 is vertical with the optical axis of LASER Light Source; Amici prism 3 is in interference light path difference modulating part (6) back, and light splitting surface becomes miter angle with+1 grade of light path, and light splitting surface is parallel with the grating grid line; Catoptron 7 is on-1 grade of light path, and the minute surface of catoptron 7 is parallel with the grating grid line, and makes-1 grade of light reflection back become miter angle with the light splitting surface of Amici prism 3; Therefore its advantage is to reduce originally and concentrates on-1 grade of light path order of reflection on the light path, i.e. luminous energy loss can reduce ± intensity difference between 1 grade of two-beam, interferes contrast thereby improve.Its principle and a last embodiment are similar.

2) interference light path difference modulating part 6 be in+1 grade of light path on; And do not change+direction of propagation of 1 grade of light;

3) signal processing: comprise photoelectric commutator 4, signal amplifier and signal processing circuit 5; Photoelectric commutator 4 is arranged on Amici prism 3 backs with optical axis and receives interference signal, and its output terminal is connected with signal processing circuit 5 with signal amplifier.

Claims (2)

1. the micro-displacement sensor based on the PGC demodulated interferential scanning is made up of grating interference, the modulation of interference light path difference and three parts of signal Processing; Wherein:

1) grating interference part: comprise laser diode (1), sinusoidal amplitude gratings strips (2), Amici prism (3) and catoptron (7); Sinusoidal amplitude gratings strips (2) is vertical with the optical axis of LASER Light Source; Amici prism (3) is on the optical grating diffraction+1 grade light path, and light splitting surface becomes miter angle with+1 grade of light path, and light splitting surface is parallel with the grating grid line; Catoptron (7) is in interference light path difference modulating part (6) back, and the minute surface of catoptron (7) is parallel with the grating grid line, and makes-1 grade of light reflection back become miter angle with the light splitting surface of Amici prism (3);

2) interference light path difference modulating part (6) is on-1 grade of light path, and does not change the direction of propagation of-1 grade of light;

3) signal processing: comprise photoelectric commutator (4), signal amplifier and signal processing circuit (5); Photoelectric commutator (4) is arranged on Amici prism (3) back with optical axis and receives interference signal, and its output terminal is connected with signal processing circuit (5) with signal amplifier; It is characterized in that:

Described interference light path difference modulating part (6) comprises four eyeglasses (6.1,6.4,6.2,6.3), two pedestals (6.5,6.6), piezoelectric ceramics Vib. (6.7) and modulation signal generator (6.8); First eyeglass (6.1) and the 4th eyeglass (6.4) are separately fixed at 90 of first pedestal (6.5) and spend on two faces of corner angle, second eyeglass (6.2) and prismatic glasses (6.3) are separately fixed at 90 of second pedestal (6.6) and spend on two faces of V-type grooves, second pedestal (6.6) bottom surface or first pedestal (6.5) bottom surface are fixed on the vibration plane of piezoelectric ceramics Vib. (6.7), the corner angle of first pedestal (6.5) do not overlap with second pedestal (6.6) V-type groove, and piezoelectric ceramics Vib. (6.7) is driven by modulation signal generator (6.8).

2. the micro-displacement sensor based on the PGC demodulated interferential scanning is made up of grating interference, the modulation of interference light path difference and three parts of signal Processing; Wherein:

1) grating interference part: comprise laser diode (1), sinusoidal amplitude gratings strips (2), Amici prism (3) and catoptron (7); Sinusoidal amplitude gratings strips (2) is vertical with the optical axis of LASER Light Source; Amici prism (3) is in interference light path difference modulating part (6) back, and light splitting surface becomes miter angle with+1 grade of light path, and light splitting surface is parallel with the grating grid line; Catoptron (7) is on-1 grade of light path, and the minute surface of catoptron (7) is parallel with the grating grid line, and makes-1 grade of light reflection back become miter angle with the light splitting surface of Amici prism (3);

2) interference light path difference modulating part (6) be in+1 grade of light path on; And do not change+direction of propagation of 1 grade of light;

3) signal processing: comprise photoelectric commutator (4), signal amplifier and signal processing circuit (5); Photoelectric commutator (4) is arranged on Amici prism (3) back with optical axis and receives interference signal, and its output terminal is connected with signal processing circuit (5) with signal amplifier; It is characterized in that:

Described interference light path difference modulating part (6) comprises four eyeglasses (6.1,6.4,6.2,6.3), two pedestals (6.5,6.6), piezoelectric ceramics Vib. (6.7) and modulation signal generator (6.8); First eyeglass (6.1) and the 4th eyeglass (6.4) are separately fixed at 90 of first pedestal (6.5) and spend on two faces of corner angle, second eyeglass (6.2) and prismatic glasses (6.3) are separately fixed at 90 of second pedestal (6.6) and spend on two faces of V-type grooves, second pedestal (6.6) bottom surface or first pedestal (6.5) bottom surface are fixed on the vibration plane of piezoelectric ceramics Vib. (6.7), the corner angle of first pedestal (6.5) do not overlap with second pedestal (6.6) V-type groove, and piezoelectric ceramics Vib. (6.7) is driven by modulation signal generator (6.8).

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