Summary of the invention
The technical problem to be solved by the present invention is to improve distance resolution to realize high-precision velocity information and apart from letter
Breath measurement.
In order to solve the above-mentioned technical problem, it is modulated the technical solution of the present invention is to provide a kind of based on pseudo-random code phases
With the range-measurement system that tests the speed of heterodyne detection, which is characterized in that including laser, by the first coupler by the output beam of laser
It is divided into two parts, a part of light beam is light beam one, and another part light beam is light beam two;
Light beam one input electro-optic phase modulator, by arbitrary waveform generator driving electro-optic phase modulator to light beam one into
After row phase-modulation, then amplify via fiber amplifier, into circulator, on the one hand circulator passes through telescope will modulation amplification
Light beam one afterwards is launched, and on the other hand receives reflected echo-signal light by telescope;
Light beam two inputs acousto-optic frequency shifters, utilizes light beam two to generate by sinusoidal signal generator driving acousto-optic frequency shifters intrinsic
Signal light, the second coupler receive the intrinsic signals light from acousto-optic frequency shifters and the echo-signal from circulator simultaneously
The mixed signal output port of light, the second coupler is connected with balanced detector, generates coherent light signal by balanced detector, by
Computer is acquired by acquisition unit through the amplified coherent light signal of amplifier, and acquisition unit acquires random waveform simultaneously
The electro-optic phase modulator driving signal of device output, when being realized between acquisition unit and arbitrary waveform generator by external trigger
Between it is synchronous;
In a computer, coherent light signal is multiplied with the electro-optic phase modulator driving signal of different delays and is Fourier
Transformation, the corresponding retardation of Fourier transformation peak value maximum represent range information.
Preferably, in the computer, how general the difference on the frequency of Fourier transformation crest frequency and acousto-optic frequency shifters be
Frequency displacement is strangled, obtains corresponding velocity information by mathematical computations.
Preferably, laser is 1550nm single-longitudinal-mode fiber laser.
Preferably, the electro-optic phase modulator is lithium niobate high speed electro-optical phase-modulator.
Preferably, the photo-coupler that first coupler is 1: 99, wherein 1% light is the light beam two;99%
Light is the light beam one.
Preferably, the telescope is transmitting and the telescopic system for receiving common optical axis.
Preferably, the acquisition unit is double-channel AD collecting card.
There is provided a kind of using above-mentioned based on pseudo-random code phases modulation and outer for another technical solution of the invention
The range-measurement system that tests the speed of difference detection test the speed the method for ranging, characterized in that it comprises the following steps:
The light beam that laser exports is divided into light beam one and light beam two by the first coupler by the first step, and light beam one successively passes through
After crossing electro-optic phase modulator and fiber amplifier, then launched by telescope via circulator;
Meanwhile acousto-optic frequency shifters will form intrinsic signals light after two shift frequency of light beam;
Second step, circulator receive the echo-signal light for being emitted to target back reflection and returning, the second coupling by telescope
Device receives the echo-signal light from circulator and the intrinsic signals light from acousto-optic frequency shifters simultaneously, then via balanced detector
Coherent light signal is generated, coherent light signal acquires amplified coherent light signal simultaneously by the amplification of amplifier, acquisition unit
And computer is inputed to after the electro-optic phase modulator driving signal of arbitrary waveform generator output;
Third step, in a computer, amplified coherent light signal successively drive with the electro-optic phase modulator of different delays
Dynamic signal multiplication simultaneously passes through Fast Fourier Transform (FFT), obtains the image of different delays lower frequency Yu signal normalization intensity;
Delay time t=nT corresponding to Fourier transformation peak value maximum0, in formula, T0For electro-optic phase modulator driving
Signal element width, n are the number successively postponed, distance L=cnT locating for target0/ 2, in formula, c is the light velocity;
The corresponding frequency of Fourier transformation peak value is f 'm, then available crest frequency f ' at this timemWith acousto-optic frequency shifters
Difference on the frequency fd=f 'm-fm, in formula, fmFor the frequency shift amount of acousto-optic frequency shifters, difference on the frequency fdAs Doppler frequency shift, then target velocity
Basic principle of the invention is be divided as two parts laser by coupler, and most laser pass through electric light phase
Position modulator carries out pseudo-random code phases modulation, and modulated laser is used as shoot laser after fiber amplifier, by telescope
Launch, sub-fraction is used for coherent detection as intrinsic light by acousto-optic frequency shifters shift frequency;Echo laser and intrinsic light into
It is relevant to enter coupler, coherent light is converted to electric signal by photoelectricity balanced detector, and is collected and converted by double-channel AD collecting card
For digital signal, the electro-optic phase modulator driving of another channel acquisition arbitrary waveform generator output of double-channel AD collecting card
Signal simultaneously takes turns doing different time delays.The electro-optic phase modulator driving signal that coherent signal successively postpones with different time
It is multiplied and does Fourier transformation, obtain different time delay lower frequency and signal normalization intensity, wherein Fourier transformation peak value
Time delay corresponding to maximum reflects range information, and the frequency of Fourier transformation crest frequency and acousto-optic frequency shifters frequency
Rate difference is Doppler frequency shift, and is greater than Laser Modulation frequency using sample frequency, to obtain high-precision target velocity
And range information.
The present invention has following characteristics:
1, system improves electrical efficiency as the optical fibre device in light source, optical path using maturation using optical fiber laser and leads to
It crosses optical fiber and optical circuit is simplified into attended operation, these features make the power consumption of system become smaller, and quality is lighter, and stability is added
By force.
2, modulation technique uses high speed pscudo-random codc modulation technology, and insertion loss is small, and extinction ratio is high, so that in peak value
Also good signal-to-noise ratio can be obtained under the echo-signal of power, improve distance resolution.The modulation rate of the system can reach
1GHz, i.e. pseudo noise code Baud Length are 1ns, and the distance resolution of system can reach 15cm with this condition.
3, system uses heterodyne detection technology.Using heterodyne detection, it is effectively exaggerated the power of echo-signal, so that
This part of system coherent detection can work to be limited in quantum noise, obtains more high s/n ratio than direct detection;
4, electro-optic phase modulator driving signal and double-channel AD collecting card processing data are associated in time, and distance is visited
It surveys and speed detection is not discrete optical path, the present invention can accurately obtain the speed and range information of target simultaneously.
Specific embodiment
In order to make the present invention more obvious and understandable, hereby with preferred embodiment, and attached drawing is cooperated to be described in detail below.
First, referring to fig. 1, and Fig. 1 is a kind of survey based on pseudo-random code phases modulation and heterodyne detection provided by the invention
Fast range-measurement system overall structure block diagram.As seen from Figure 1, high precision speed-measuring range laser radar system of the present invention is by laser 1, and
One coupler 2, electro-optic phase modulator 3, fiber amplifier 4, circulator 5, telescope 6, sinusoidal signal generator 7, acousto-optic move
Frequency device 8, the second coupler 9, balanced detector 10, amplifier 11, double-channel AD collecting card 12 have signal processing, control, meter
Calculation, acquisition, the computer 13 of display function, external trigger 14 and arbitrary waveform generator 15 form.Its positional relationship is: by
The output beam of the laser 1 is divided into two parts, i.e. light beam one and light beam two by the first coupler 2, and the first coupler 2 is
1: 99 photo-coupler, 1% light are light beam two, and 99% light is light beam one.Light beam one passes through by arbitrary waveform generator 15
The electro-optic phase modulator 3 of driving carries out phase-modulation, then after amplifying via fiber amplifier 4.Amplified light beam is logical
Circulator 5 is crossed to be launched by telescope 6.Light beam two is made by 8 shift frequency of acousto-optic frequency shifters driven by sinusoidal signal generator 7
Optical heterodyne detection is used for for intrinsic signals light.Output port phase of one input port of the second coupler 9 with above-mentioned circulator 5
Even to receive the echo-signal that transmitting is returned to target back reflection, the output end phase of another input port and acousto-optic frequency shifters 8
Connection.The input port of the mixed signal output port connection balanced detector 10 of second coupler 9, is produced by balanced detector 10
Raw coherent light signal is acquired after coherent light signal amplifies using amplifier 11 by double-channel AD collecting card 12.Meanwhile bilateral
Road AD capture card 12 also acquires the electro-optic phase modulator driving signal of the generation of arbitrary waveform generator 15.Double-channel AD collecting card
12 output end is connected with computer 13.In computer 13, the electro-optic phase modulator of coherent light signal and different delays is driven
Dynamic signal multiplication simultaneously does Fourier transformation.The corresponding retardation of Fourier transformation peak value maximum represents range information.Fourier
The difference on the frequency for converting crest frequency and acousto-optic frequency shifters is Doppler frequency shift, show that corresponding speed is believed by mathematical computations
Breath.
The specific device that the present embodiment uses are as follows: laser 1 is 1550nm single-longitudinal-mode fiber laser;Electric light phase-modulation
Device 3 is lithium niobate high speed electro-optical phase-modulator;Arbitrary waveform generator 15 is gathered around there are two output channel, respectively electric light phase
Modulator 3 provides driving signal and double-channel AD collecting card 12 provides pseudo noise code signal;The optocoupler that first coupler 2 is 1: 99
Clutch.Wherein 1% light is used as intrinsic signals light through 8 shift frequency of acousto-optic frequency shifters;99% light is pressed by electro-optic phase modulator 3
Phase-modulation is carried out according to pseudo noise code signal and is projected laser by telescope 6;Telescope 6 is transmitting and reception common optical axis
Telescopic system.
The test the speed detailed process of ranging of high precision speed-measuring range laser radar system of the embodiment of the present invention is:
The first step, laser 1 output laser be divided into two by the first coupler 2: 99% laser is through electric light phase
Position modulator 3 and fiber amplifier 4, the output end of fiber amplifier 4 enters circulator 5 through the first port of circulator 5, and passes through
The second port of the circulator 5 is launched by telescope 6;1% laser is used as this reference after 7 shift frequency of acousto-optic frequency shifters
Number light.
Second step, the laser launched reach target back reflection, and the echo-signal light of target is received by telescope 6, return
Wave signal light enters circulator 5 via 5 second port of circulator, and enters the second coupler 9 through the third port of the circulator 5
An input port.The output port of another input port connection acousto-optic frequency shifters 8 of second coupler 9, receives intrinsic
Signal light.The output port connection balanced detector 10 of second coupler 9 is to generate coherent light signal.10 institute of balanced detector
The coherent light signal output obtained accesses an input channel of double-channel AD collecting card 12, the binary channels after the amplification of amplifier 11
Another input channel of AD capture card 12 acquires electro-optic phase modulator driving signal by connection arbitrary waveform generator 15.
The output end of double-channel AD collecting card 12 connects computer 13.
Third step, in computer 13, coherent light signal successively with the electro-optic phase modulator driving signal of different delays
It is multiplied and passes through Fast Fourier Transform (FFT), obtain the image of different delays lower frequency Yu signal normalization intensity;
Delay time t=nT corresponding to Fourier transformation peak value maximum0, in formula, T0For electro-optic phase modulator driving
Signal element width, n are the number successively postponed, distance L=cnT locating for target0/ 2L, in formula, c is the light velocity;
The corresponding frequency of Fourier transformation peak value is f 'm, then available crest frequency f ' at this timemIt is moved with acousto-optic frequency shifters 8
The difference on the frequency f of amountd=f 'm-fm, in formula, fmFor the frequency shift amount of acousto-optic frequency shifters 8, difference on the frequency fdAs Doppler frequency shift, then target
Speed