CN1563890A - Double-sine phase modulation real-time interference range finder - Google Patents
Double-sine phase modulation real-time interference range finder Download PDFInfo
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Abstract
A dual sinusoidal phase modulation real-time interferometric rangefinder comprising: the light source is connected with a first driver with a direct current power supply and a first sinusoidal signal generator, and a collimating lens, a beam splitter and a measured object are sequentially arranged coaxially in the advancing direction of a light beam emitted by the light source, wherein the measured object is arranged outside the casing, and the device is characterized in that: a reflecting mirror, a second driver and a second sinusoidal signal generator are arranged on a reflecting light path of the beam splitter; a photoelectric conversion device and a signal processing system are arranged along a reflection light path on a reflection surface of the beam splitter relative to the object to be measured; the signal processing system comprises two input ports and an output port, wherein the first input port is connected with the output end of the photoelectric conversion device, the second input port is connected with the first sinusoidal signal generator, and the output port is connected with the oscilloscope. The invention has the characteristics of real-time measurement, strong anti-interference capability, high measurement precision and large measurement range.
Description
Technical field:
The present invention relates to stadimeter, particularly a kind of pair of real-time interfeerometry ranging instrument of sinusoidal phase modulation.
Background technology:
Because the temperature stability of semiconductor laser (hereinafter to be referred as LD) wavelength is solved preferably, the semiconductor laser interference instrument is is researched and developed widely.LD is except that advantages such as volume is little, power-saving, price is low, and another outstanding advantage is that wavelength-modulated is easy.This makes the light heterodyne technology that can improve measuring accuracy can realize by the injection current of direct modulation LD simply in the semiconductor laser interference instrument.The interferometer that is used for measuring distance that proposes such as Li-Wuu Mr. Chang of Taiwan National Central University (technology 1:Lin-Wuu Chang formerly, Pie-Yau Chien and Ching-tingLee, " Measurement of absolute displacement by a double-modulation techniquebased on a Michelson interferometer; " App Opt 1999,38 (13), 2843-2847), by to having realized measurement as Sine Modulated to displacement and distance as the optical path difference of the optical frequency of the semiconductor laser of light source and interferometer.
Formerly in the technology 1, the interference signal that photodetector obtains is:
I
out＝(I
0/16){cos(
t-
r)[J
0(
m)+2J
2(
m)cos(2ω
mt)+… (1)
+sin(
t-
r)[2J
1(
m)sin(ω
mt)+2J
3(
m)sin(3ω
mt)+…]}
Wherein: φ
t=2 π ν
0L
t/ c is the phase place of thing light, φ
r=2 π ν
0L
r/ c is the phase place of reference light, φ
m=2 π ν
m(L
t-L
r)/c is the phase differential that modulation causes, J
n(φ) be n rank Bessel's functions.I
0It is the output intensity of laser instrument.Utilize phase lock amplifying technology and low-pass filtering technique to obtain
I
3ω＝(I
0/8)J
3[2πν
m/c(L
0+L
msinω
pt)]sin[2πν
c/c(L
0+L
msinω
pt)] (2)
L
0=L
t-L
rIt is the static optical path difference of interferometer.(2) can to regard angular frequency as be ω to formula
p, amplitude is (I
0/ 8) J
3[2 π ν
m/ c (L
0+ L
mSin ω
pT)] sinusoidal signal obtains the amplitude of this signal by gate circuit with from hybrid circuit, by detecting the ratio of this amplitude and light intensity, i.e. and 3 rank Bessel's function J
3(2 π ν
m/ cL
0) size, just can obtain L
0Numerical value.
This is the shortcoming of technology 1 formerly:
(1) formerly in the technology 1, when the wavelength of semiconductor laser changes with the variation of modulating current, its light intensity I
0Also simultaneously modulated, i.e. light intensity I in formula (1) and formula (2)
0Not a constant, but the variation that does not stop in time, there is an error all the time in the 3 rank Bessel's functions that record like this, have influenced measuring accuracy; And formerly do not take interference protection measure in the technology 1 in measuring process, interference signal is subjected to Effect of Environmental such as extraneous vibration, air turbulence, and these influences are same transmits, and brings inevitable error for last measurement result.
(2) as the formula (2), formerly technology 1 is by detecting 3 rank Bessel's function J
3(2 π ν
m/ cL
0) obtaining distance, its maximum measurement range is subjected to the restriction of 3 rank Bessel's function character and semiconductor laser modulation frequency difference, and maximum range only is 4.186cm.
Summary of the invention
The technical problem to be solved in the present invention is to overcome the deficiency of above-mentioned technology formerly, and a kind of pair of real-time interfeerometry ranging instrument of sinusoidal phase modulation is provided, and it should have the high and big advantage of measurement range of measuring accuracy.
Technical solution of the present invention is as follows:
A kind of pair of real-time interfeerometry ranging instrument of sinusoidal phase modulation comprises:
＜1〉light source links to each other with first driver of band direct supply with the first card string signal generator, on the working direction of this light emitted light beam, be equipped with collimation lens, beam splitter and testee successively with optical axis ground, wherein testee places outside the casing, it is characterized in that:
＜2〉on the reflected light path of beam splitter, be equipped with catoptron, second driver and second sinusoidal signal generator;
＜3〉along being equipped with electrooptical device and signal processing system on the reflected light path on the reflecting surface of the relative testee of beam splitter;
＜4〉this signal processing system comprises two input ports and an output port, and its first input end mouth links to each other with the output terminal of electrooptical device, and second input port links to each other with first sinusoidal signal generator, and output port is connected with oscillograph.
The structure of described signal processing system comprises phase discriminator, low-pass filter circuit, phase-locked loop circuit, subtraction circuit, adding circuit and division circuit, the first input end mouth of this signal processing system links to each other with low-pass filter circuit with its phase discriminator simultaneously, the output of this phase discriminator and low-pass filter circuit connects phase-locked loop circuit, the two-way output of phase-locked loop circuit is input to subtraction circuit and adding circuit respectively, the output termination division circuit of subtraction circuit and adding circuit, the output terminal of this division circuit, be that output port connects oscillograph, second input port of this signal processing system links to each other with phase-locked loop circuit.
Described light source is the semiconductor laser instrument.
Described catoptron can produce sinusoidal vibration under second driver and the driving of second sinusoidal signal generator.
Described electrooptical device can be photodiode or photomultiplier.
Advantage of the present invention:
Overcome in the technology 1 formerly because light intensity is modulated and interference signal is subjected to the influence of factor such as external interference to measurement result easily, improved measuring accuracy, measurement range expands 12cm to from 4.2cm.
Description of drawings:
Fig. 1 is the structured flowchart of the two real-time interfeerometry ranging instrument of the sinusoidal phase modulation specific embodiments of the present invention.
Fig. 2 is the structured flowchart of the signal processing system of the two real-time interfeerometry ranging instrument of sinusoidal phase modulation of the present invention.
Embodiment:
Please consult Fig. 1 and Fig. 2 earlier, Fig. 1 is the two real-time interfeerometry ranging instrument of the sinusoidal phase modulation specific embodiment structured flowcharts of the present invention, and Fig. 2 is the structured flowchart of the signal processing system of the two real-time interfeerometry ranging instrument of sinusoidal phase modulation of the present invention.As seen from the figure, the two real-time interfeerometry ranging instrument of sinusoidal phase modulation of the present invention comprise:
＜1〉semiconductor laser 1 links to each other with first driver 9 of the band direct supply 10 and first sinusoidal signal generator 11, on the direction that the emission light beam of this semiconductor laser 1 advances, be equipped with collimation lens 2, beam splitter 3 and testee 5 successively with optical axis ground, wherein testee 5 places outside the casing 19, is characterized in:
＜2〉be equipped with catoptron 4, second driver 12 and second sinusoidal signal generator 13 on the reflected light path of beam splitter 3, this catoptron 4 can produce sinusoidal vibration under the driving of second sinusoidal signal generator 13 and second driver 12;
＜3〉along being equipped with on the reflected light path on the reflecting surface of beam splitter 3 relative testees 5 and electrooptical device 6 and signal processing system 7;
＜4〉this signal processing system 7 comprises two input port 7a, 7b and an output port 7c, its first input end mouth 7a links to each other with the output terminal of electrooptical device 6, the second input port 7b links to each other with first sinusoidal signal generator 11, and output port 7c is connected with oscillograph 8.The output signal of this electrooptical device 6 is input to signal processing system 7, and the result who handles through signal processing system 7 is shown by oscillograph 8.
The structure of described signal processing system 7 as shown in Figure 2, comprise phase discriminator 71, low-pass filter circuit 72, phase-locked loop circuit 73, subtraction circuit 74, adding circuit 75 and division circuit 76, the first input end mouth 7a of this signal processing system 7 links to each other with low-pass filter circuit 72 with phase discriminator 71 simultaneously, the output of this phase discriminator 71 and low-pass filter circuit 72 connects phase-locked loop circuit 73, the two-way output of phase-locked loop circuit 73 is input to subtraction circuit 74 and adding circuit 75 respectively, the output termination division circuit 76 of this subtraction circuit 74 and adding circuit 75, the output terminal of this division circuit 76, be that output port 7c connects oscillograph 8, the second input port 7b of this signal processing system 7 directly links to each other with phase-locked loop circuit 73.This signal processing system 7 can be come out the absolute distance information of object high-precision extract real-time from interference signal.
Said phase discriminator 13 is meant and utilizes phase sensitive detection technology and low-pass filtering technique to extract the element circuit of the amplitude of required periodic signal and phase place or other extract the interference signal circuit of variation phase in time.
Said low-pass filter circuit 14 is the above low-pass filter of quadravalence.
Said phase-locked loop circuit 15 is meant and utilizes phase-locked amplification principle to detect the element circuit of the amplitude and the phase place of periodic signal.
Said catoptron 4 is meant beam reflection elements such as the parallel flat that is coated with highly reflecting films or angle vertebra prism, and its reflectivity satisfies when measuring with after beam splitter 3 cooperates, and the object light that electrooptical device 6 receives and the beam intensity ratio of reference light approached 1: 1.
Said electrooptical device 6 comprises electrooptical devices such as photodiode or photomultiplier.
Said driver 13 be meant can be under the driving of external signal vibrative element, as piezoelectric ceramics, or the vibrating elements of loudspeaker etc.
The course of work of the present invention is roughly as follows:
The emergent light wavelength of semiconductor laser 1 is had first driver, 9 Sine Modulated of first sinusoidal signal generator 11 and direct supply 10, and catoptron 4 produces sinusoidal vibration under the driver 12 that has sinusoidal signal generator 13 drives.The wavelength of described semiconductor laser 1 is 785nm, peak power output is 20mw, laser beam after wavelength is modulated by sinusoidal current, be divided into two bundles through behind the beam splitter 3, wherein transmitted light testee 5 reflected probe light beams produce interference again with the reference beam of mirror 4 reflections that are reflected after beam splitter 3 meets, convert interference signal to electric signal with photodetector 6, be input to the first input end mouth 7a of signal processing system 7.In signal processing system 7, the electric signal of the first input end mouth 7a of signal processing system 7 input is divided into two-way, the one tunnel through phase discriminator 71, obtains
P
1(t)＝S
1(t)J
1[2πν
m/cL
0]sin[4π(L
0+L
psinω
pt)/λ
0] (3)
Another road obtains through low-pass filter circuit 72
P
2(t)＝S
1(t)J
0(2πν
m/cL
0)cos[4π(L
0+L
psinω
pt)/λ
0] (4)
The second input port 7b and the two-way output signal P of the signal processing system 7 that the modulation signal process that sinusoidal signal generator 11 sends is attached thereto
1(t), P
2(t) be input to phase-locked loop circuit 73 simultaneously, these phase-locked loop circuit 73 outputs have two direct current signals:
P
1dc＝S
1(t)J
1[2πν
m/cL
0] (5)
P
2dc＝S
1(t)J
0[2πν
m/cL
0] (6)
With above-mentioned two direct current signal P
1dc, P
2dcBe input to subtraction circuit 74 and adding circuit 75 respectively, its result sends into divider 76, and divider 76 is output as:
K in the formula
sAnd K
lBe the gain of two paths of signals behind each circuit.Output port 7c through signal processing system 7 is input in the oscillograph 8 the output of divider 76.Because the gain of each circuit and the modulating frequency ν of modulation signal in (7) formula
MKnown, light velocity c is a constant, so the big I of exporting the result at last by divider obtains the distance L of object
0
From formula (7) as can be seen, we in signal processing system 7 by will record contain 1 rank Bessel's function respectively and 0 rank Bessel's function two paths of signals is made normalized, eliminate the influence that light source intensity fluctuation and external interference are brought, thereby improved the measuring accuracy of system.And, can reduce the requirement of the modulation frequency difference of noise spectra of semiconductor lasers greatly, thereby enlarge measurement range owing to be simultaneously the two-way coherent signal to be handled.Expanded range is arrived about 12cm among the embodiment.Because whole signal processing system (7) all is made up of each circuit, can realize real-time online measuring.
During measurement, at first open the semiconductor laser 1 and first sinusoidal signal generator 11, the wavelength of noise spectra of semiconductor lasers 1 outgoing beam carries out Sine Modulated; Open second sinusoidal signal generator 13 then and drive catoptron 4 vibrations via driver 12.The signal input signal disposal system 7 of photodiode 6 outputs, its result is shown by oscillograph 8.Can obtain the absolute distance of object according to above-mentioned formula (7).When the amplitude of modulating current is 0.5mA, the experiment proved that the ultimate range that the present invention records is 12.1cm.
Claims (5)
1, a kind of pair of real-time interfeerometry ranging instrument of sinusoidal phase modulation comprises:
＜1〉light source (1) links to each other with first driver (9) of band direct supply (10) and first sinusoidal signal generator (11), on the direction that the emission light beam of this light source (1) advances, be equipped with collimation lens (2), beam splitter (3) and testee (5) successively with optical axis ground, wherein testee (5) places outside the casing (19), it is characterized in that:
＜2〉on the reflected light path of beam splitter (3), be equipped with catoptron (4), second driver (12) and second sinusoidal signal generator (13);
＜3〉along being equipped with electrooptical device (6) and signal processing system (7) on the reflected light path on the reflecting surface of the relative testee (5) of beam splitter (3);
＜4〉this signal processing system (7) comprises two input ports (7a, 7b) and an output port (7c), its first input end mouth (7a) links to each other with the output terminal of electrooptical device (6), second input port (7b) links to each other with first sinusoidal signal generator (11), and output port (7c) is connected with oscillograph (8).
2, the according to claim 1 pair of real-time interfeerometry ranging instrument of sinusoidal phase modulation, the structure that it is characterized in that described signal processing system (7) comprises phase discriminator (71), low-pass filter circuit (72), phase-locked loop circuit (73), subtraction circuit (74), adding circuit (75) and division circuit (76), the first input end mouth (7a) of this signal processing system (7) links to each other with low-pass filter circuit (72) with phase discriminator (71), the output of this phase discriminator (71) and low-pass filter circuit (72) connects phase-locked loop circuit (73), the two-way output of phase-locked loop circuit (73) is input to subtraction circuit (74) and adding circuit (75) respectively, the output termination division circuit (76) of this subtraction circuit (74) and adding circuit (75), the output terminal of this division circuit (76), be that output port (7c) connects oscillograph (8), second input port (7b) of this signal processing system (7) directly links to each other with phase-locked loop circuit (73).
3, the according to claim 1 pair of real-time interfeerometry ranging instrument of sinusoidal phase modulation is characterized in that described light source (1) is a semiconductor laser.
4, according to claim 1 pair of real-time interfeerometry ranging instrument of sinusoidal phase modulation is characterized in that described catoptron (4) can produce sinusoidal vibration under second driver (12) and second sinusoidal signal generator (13) driving.
5, according to claim 1 pair of real-time interfeerometry ranging instrument of sinusoidal phase modulation is characterized in that described electrooptical device (6) can be photodiode or photomultiplier.
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100464153C (en) * | 2007-02-07 | 2009-02-25 | 中国科学院上海光学精密机械研究所 | Real-time interference measurement device and method for nanometer precision of object surface appearance |
| CN100538260C (en) * | 2007-02-07 | 2009-09-09 | 中国科学院上海光学精密机械研究所 | Micro-displacement high-precision real-time interferometer |
| CN100547344C (en) * | 2007-02-07 | 2009-10-07 | 中国科学院上海光学精密机械研究所 | Sine phase modulation interferometer for real-time measurement of surface topography |
| CN102706282A (en) * | 2012-06-25 | 2012-10-03 | 无锡迈福光学科技有限公司 | Laser interference range finder |
| CN108680107A (en) * | 2018-05-16 | 2018-10-19 | 中北大学 | A kind of high-precision prism displacement measuring device and method based on digital servo-control |
| CN110174058A (en) * | 2019-06-06 | 2019-08-27 | 浙江理工大学 | Dynamic rrequency-offset-lock formula sinusoidal frequency scanning interferometer Models of Absolute Distance Measurement Based device and method |
| CN111897274A (en) * | 2020-08-20 | 2020-11-06 | 西安石油大学 | FPGA-based weak signal detection device and method |
-
2004
- 2004-03-30 CN CN 200410017310 patent/CN1563890A/en active Pending
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100464153C (en) * | 2007-02-07 | 2009-02-25 | 中国科学院上海光学精密机械研究所 | Real-time interference measurement device and method for nanometer precision of object surface appearance |
| CN100538260C (en) * | 2007-02-07 | 2009-09-09 | 中国科学院上海光学精密机械研究所 | Micro-displacement high-precision real-time interferometer |
| CN100547344C (en) * | 2007-02-07 | 2009-10-07 | 中国科学院上海光学精密机械研究所 | Sine phase modulation interferometer for real-time measurement of surface topography |
| CN102706282A (en) * | 2012-06-25 | 2012-10-03 | 无锡迈福光学科技有限公司 | Laser interference range finder |
| CN102706282B (en) * | 2012-06-25 | 2014-08-20 | 无锡迈福光学科技有限公司 | Laser interference range finder |
| CN108680107A (en) * | 2018-05-16 | 2018-10-19 | 中北大学 | A kind of high-precision prism displacement measuring device and method based on digital servo-control |
| CN110174058A (en) * | 2019-06-06 | 2019-08-27 | 浙江理工大学 | Dynamic rrequency-offset-lock formula sinusoidal frequency scanning interferometer Models of Absolute Distance Measurement Based device and method |
| CN110174058B (en) * | 2019-06-06 | 2020-06-23 | 浙江理工大学 | Dynamic offset frequency locking type sine frequency scanning interference absolute distance measuring device and method |
| CN111897274A (en) * | 2020-08-20 | 2020-11-06 | 西安石油大学 | FPGA-based weak signal detection device and method |
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