The lidar measurement instrument of Accurate Measurement object angle and angular velocity
Technical field
The utility model relates to laser radar detection field, is specifically related to the lidar measurement instrument of a kind of Accurate Measurement object angle and angular velocity.
Background technology
Lidar measurement technology is as a kind of brand-new measurement means, for the spatial information of people's active obtaining high-spatial and temporal resolution provides convenience, therefore be widely used in military affairs, industry, atmospheric exploration and aerospace field, particularly airborne laser radar measuring system and GPS etc.The transmitter of general laser radar can be divided into two classes, and a class is continuous wave laser, and another kind of is pulsed laser.It is narrow that continuous wave laser has spectral line, and monochromaticity is good, the feature that detection accuracy is high, but aspect laser energy and power, performance is not good enough, is therefore often applied to the detection (< 1km) of short-distance and medium-distance.By contrast, pulsed laser has high peak power and single pulse energy, can be for long-range detection (> 1km).But, because general laser pulse sequence does not possess stable phase angle relation, so this type of radar is mainly to come implementation space to survey by surveying the strength information of echo.Comparatively limited in view of the quantity of information that laser-impulsed radar provides, the single that this radar is mainly used in direct ranging pulse calculates the distance of target object two-way time, angle, and the information such as speed, process is simple, but detection accuracy is lower.
Based on above-mentioned two class laser instruments, the Laser Measuring angle and the angular velocity technology that adopt at present mainly can be divided into the phase place angle-measuring method based on continuous wave laser, the flight time angle-measuring method based on pulsed laser and the four-quadrant Tracking Angle Measurement method that is applicable to all kinds of laser instruments.What phase place angle-measuring method adopted is a kind of light heterodyne technology, calculates the actual range of three the non-colinear reference points in target object surface by the mode of measure phase difference, then utilizes solid geometry knowledge to calculate the inclination angle of 3 determined planes.This method measuring accuracy is higher, but range is limited, and system is too complicated, and laser energy is had relatively high expectations.Time-of-flight method angle measurement and phase place ratio juris are similar, and what just adopt here is the actual range that calculates definite reference point of time of pulse flight.This angle-measuring method can effectively utilize single pulse energy, but measuring accuracy is lower, and range is seriously limited to the repetition frequency of pulse.In addition, this method can only obtain the strength information of echo, cannot obtain phase information, so quantity of information is limited.If this method is used in space, be easily subject to the interference of extraneous radiation, the time jitter of pulsed light is large, and the precision of measuring is all had a great impact.Compare above two kinds of methods, four-quadrant tracing is applicable to various ranges, and can real-time follow-up target object, has higher measuring accuracy.But the measuring accuracy of this method also often can be subject to the impact of environmental perturbation and laser amplitude jitter.
In sum, although it is a lot of with the method for angular velocity to utilize optical radar to take measurement of an angle, all exist various shortcomings and deficiencies.
Summary of the invention
The purpose of this utility model is according to above-mentioned the deficiencies in the prior art, the lidar measurement instrument of a kind of Accurate Measurement object angle and angular velocity is provided, this measuring instrument adopts two optical lasers as detection source and local vibration source, by laser coherence synergistic effect and four-quadrant imaging technique, the angle of unknown object and angular velocity are accurately measured, thereby make to survey light and possessed the quantity of information that stable time-frequency domain characteristic has expanded optical detection, not only can provide the information such as intensity and polarization for measuring, reliable phase information can also be provided.
The utility model object realizes and being completed by following technical scheme:
The lidar measurement instrument of a kind of Accurate Measurement object angle and angular velocity, it is characterized in that: described lidar measurement instrument comprises respectively combs laser instruments as two light of transmitting terminal, local oscillator end, the local oscillator pulse that the direct impulse that wherein said transmitting terminal light comb laser instrument sends is sent with described local oscillator end light comb laser instrument after via described target object reflection is by the bundling device formation beat signal that overlaps, described beat signal via a lens focus in a 4 quadrant detector.
The direct impulse light path of described transmitting terminal light comb laser instrument successively after an optical shaping device, described target object, wide-angle lens, high reflective mirror again to described light combination mirror.
Described transmitting terminal light comb laser instrument and described local oscillator end light comb laser instrument connect locking by a rubidium frequency standard respectively.
Described 4 quadrant detector is connected to a data processing circuit.
The utility model has the advantages that: detection process is simple, and had concurrently the high precision characteristic of continuous light heterodyne detection and pulsed survey in the high feature of pulse energy; Meanwhile, phase method and the deficiency of time-of-flight method on detection range have in the past been overcome.
Accompanying drawing explanation
Fig. 1 is system architecture schematic diagram of the present utility model;
Fig. 2 is theory diagram of the present utility model;
Fig. 3 is that the utility model optical heterodyne is followed the tracks of the pulse sequence figure surveying;
Fig. 4 is the ultimate principle figure of the utility model measurement of angle;
Fig. 5 is the schematic diagram of the utility model four-quadrant imaging detection;
Fig. 6 is the front elevation of 4 quadrant detector in the utility model.
Embodiment
Below in conjunction with accompanying drawing, by embodiment, the utility model feature and other correlated characteristic are described in further detail, so that technician's of the same trade understanding:
As shown in Fig. 1-6, in figure, mark 1-13 is respectively: transmitting terminal 1, local oscillator end 2, rubidium frequency standard 3, optical shaping device 4, wide-angle lens 5, high reflective mirror 6, light combination mirror 7, lens 8,4 quadrant detector 9, data processing circuit system 10, target object 11, direct impulse 12, local oscillator pulse 13.
Embodiment: as shown in Figure 1, the lidar measurement instrument in the present embodiment comprises transmitting terminal 1, local oscillator end 2, both all adopt high-power fiber light comb (light comb laser instrument), and transmitting terminal 1 and local oscillator end 2 connect and control by rubidium frequency standard 3.Transmitting terminal 1 send direct impulse 12 via the shaping of optical shaping device 4 to target object 11, target object 11 reflection direct impulses 12 are in order to collect on the wide-angle lens 5 of direct impulse 12 echoed signals, wide-angle lens 5 reaches echoed signal on light combination mirror 7 via high reflective mirror 6, the local oscillator pulse 13 that light combination mirror 7 sends local oscillator end 2 overlaps with direct impulse 12 and forms beat signal, this beat signal images on 4 quadrant detector 9 via lens 8, this 4 quadrant detector 9 is exported image-forming information to data processing circuit system 10 with current forms after receiving beat signal.
In the present embodiment, adopt laser frequency comb technology, utilize the chamber of phase-locked loop circuit FEEDBACK CONTROL one light comb laser instrument long, make pulse repetition rate stable; Meanwhile, adopt the drift of acousto-optic frequency shifter timely compensate for laser carrier envelope phase frequency (zero-frequency), realize the stable of laser zero-frequency.
As shown in Figure 2, adopt pulsed optical heterodyne detection technology, transmitting terminal 1 and local oscillator end 2 and phase stabilization, and there is definite phase relation, the echo of direct impulse 12 after target object 11 reflection interferes by light combination mirror 7 with local oscillator pulse 13 after space-time overlaps, and produces beat signal focusing on 4 quadrant detector 9.
As shown in Figure 3, adopting and follow the tracks of Detection Techniques, there is the difference DELTA f of a repetition frequency in local oscillator pulse 13 and direct impulse 12.So, the echo that local oscillator pulse 13 can be reflected via target object 11 in cycle Δ T=1/ Δ f interscan direct impulse 12, surveys the tracking of mobile object thereby realize.
As shown in Figure 5,6, adopt four-quadrant imaging technique, the xsect of launch spot is divided into tetra-regions of ABCD, respectively four photodiodes of corresponding 4 quadrant detector 9.Because target object 11 has an inclination angle [theta], make the different piece of launch spot to return to receiver with the different echo times.This mistiming cause the echo of direct impulse 12 and the phase differential between local oscillator pulse 13 different, then make the power of the heterodyne signal that four photodiodes detect distinguish to some extent.By analyzing the relative strong or weak relation of Si Ge road signal, can draw the luffing angle of target object 11.
The present embodiment is in the specific implementation: transmitting terminal 1 adopts a high power Yb dosed optical fiber light comb, output power 10W, centre wavelength is near 1030nm, pulse width 1ps, repetition frequency 100.000132MHz, live width is less than 1mHz, and zero-frequency live width is less than 1mHz, and the time jitter of carrier envelope position phase is less than 100as.Local oscillator machine is selected a repetition frequency 100.005303MHz, the Yb dosed optical fiber light comb of power 0.5W.
Because local oscillator pulse 13 is very approaching with the repetition frequency of direct impulse 12, the echo of direct impulse 12 becomes beat signal by a light combination mirror 7 with local oscillator pulse 13 coincident configurations, focuses on and on 4 quadrant detector 9, carries out imaging afterwards through the lens 8 of a focal length 10cm.Due to the poor about 5kHz of repetition frequency of the echo of local oscillator pulse 13 and direct impulse 12, so the tracking cycle of this system is 0.2ms.
As shown in Figure 4, have a pitching angle theta between target object 11 and X-axis, between hot spot AB and CD, have a path length difference L θ, L is hot spot spacing.According to geometric relationship, can draw: θ=λ/4L * [(I
a+ I
b)-(I
c+ I
d)]/(I
max-I
min), I wherein
maxand I
minbeing respectively echo and local oscillator light phase poor is 0 and total output current during π, can calculate this pitching angle theta.By measuring the angle of pitch variation delta θ in the unit interval, can be calculated by differential formulas ω=Δ θ/Δ t the angular velocity of this target object 11.