CN1308700C - Electro-optical modulation laser distance measuring method and device - Google Patents
Electro-optical modulation laser distance measuring method and device Download PDFInfo
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Abstract
The electro-optical modulation laser ranging method and device utilize the polarization characteristic of laser as information carrier to carry out laser ranging: by utilizing the transverse electro-optic effect of the uniaxial crystal, and matching with the polarization beam splitter and the polarization analyzer, when half-wave voltage is applied to the uniaxial crystal in the direction parallel to the optical axis, an optical pulse taking the time t required by the laser to reciprocate the distance to be measured as the pulse width is extracted by utilizing the characteristic that the uniaxial crystal twists the polarization direction of linearly polarized light by 90 degrees. The invention overcomes the error introduced by the photoelectric conversion process and the circuit system in the existing distance measuring method. The invention has simple and easy structure, convenient operation, no environmental influence, strong anti-interference capability and wide measuring distance range, can measure the distance of several meters at the latest and can measure the distance of 10 kilometers at the farthest under the condition of higher energy of the laser. The measuring precision is high and can reach centimeter-level measuring precision.
Description
Technical field
The present invention relates to laser ranging, particularly a kind of electro light modulation laser distance measuring method and device thereof can be applicable to numerous areas such as industrial and agricultural production, military affairs, communication, remote sensing.
Background technology
The high-acruracy survey of adjusting the distance is one of gordian technique of modernization of the country construction numerous areas.Along with development of science and technology, the scope and the accuracy requirement of the measurement of adjusting the distance are more and more higher.Laser becomes the first-selected instrument of range observation as the information carrier with high monochromaticity, collimation, coherence.Advanced both at home and abroad at present stadimeter all utilizes laser to improve the degree of accuracy of range finding as information carrier.
Formerly technology [1] is (referring to Kozo Ohtani, Misuru Baba, A rangefindingapproach by detecting the position and the incident angle of alight-stripe, IEEE Instru.and Mea.Techno.Conf.2002) be a kind of distance-finding method of geometrical optics.The laser instrument emission of lasering beam is received by PSD or CCD behind target reflection, according to facula position that receives and the geometry site between laser instrument and the receiver, calculates distance between target and the detector then.This method is mainly used in industrial face type profile measurement, the type reconstruct of 2D/3D face and location etc., and measuring relative accuracy is about 0.85%, can only survey very short distance.Along with the increase of distance, precision sharply descends.
Formerly technology [2] is (referring to Raimo Ahola, Risto Myllyla, A new method formeasuring the time-of-flight in fast laser range finding, [J] .Proc.SPIE vol.654, pp19-, 1986) be a kind of distance-finding method that utilizes the light pulse flight time.Send very short pulse laser of a duration by pulsed laser, be referred to as main ripple.Through directive measured target behind the testing distance L, the pulse laser of being returned by target reflection is referred to as echo, echo is received by photodetector after returning stadimeter, according to the time interval between main ripple signal and the echoed signal, be that laser pulse is transmitted into t two-way time that returned by target reflection from laser instrument, just can calculate the distance of target to be measured, i.e. L=ct/2, wherein c is the light velocity.This method also needs complicated processing of circuit system except that the laser instrument that needs superior performance.Will be electric pulse with the Conversion of energy of the main glistening light of waves pulse of part at first, shaping be after the gating circuit flip-flop number, and the time pulse number that begins clock oscillator is sent is counted; Be detected device after echoed signal arrives then and be converted into electric signal once more, the electricity processing procedure through same stops the counting to time pulse signal, determines light pulse t two-way time by the number of time tick.Be converted in the process of electric signal and in the processing of circuit system to electric signal at light signal and all can introduce a lot of errors.
Formerly technology [3] is (referring to Fujima I, Seta K, Matsumoto H and O ' ishi T1988GHz traveling-wave optical modulator for precision distancemeasurement Proc.SPIE vol 889 pp 86-90) be a kind of distance-finding method that utilizes the continuous laser phase information.Phase laser distance is realized range finding by measuring the high frequency modulated phase differential.Light source in the instrument sends continuous light, by becoming light modulated directive target after the modulators modulate, the light intensity of the light modulated cycle of intercropping at any time changes, adopt sine wave modulation, the phase place of the sinusoidal wave complete cycle issue in the mensuration light wave two-way process and the sine function of not enough one-period, just can determine the interval t of the two-way time of light wave, thus calculate range finding from.This method still needs light signal is converted into electric signal after Circuits System is handled, and relatively launches and accept the phase differential of sine wave by the electronics phase comparator, but also needs to increase the electrical devices of the sinusoidal light intensity of accurate modulation.
Formerly technology [4] is (referring to S F Collins, M M Murphy, K T V Grattan, etal.Asimple laser diode ranging scheme using an intensity modulatedFMCW approach[J] .Meas.and Tech., 1993,4:1437-1439) be a kind of distance-finding method that utilizes the continuous laser frequency information.The FM-CW laser ranging principle is by launching the continuously adjustable laser of a frequency, receives through the return frequency of laser of target reflection by measurement and calculates distance.Receive light and have frequency drift owing to warbling with emission light, so will produce beat frequency in frequency mixer, this beat frequency is directly proportional with testing distance.This method still needs light signal is converted into electric signal after Circuits System is handled, but also needs to increase the additional circuitry of regulating laser frequency.
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 electro light modulation laser distance measuring method and device thereof are provided, and to avoid having introduced complicated Circuits System, overcomes the error of being introduced by photoelectric conversion process and Circuits System.
Technical solution of the present invention is as follows:
A kind of electro light modulation laser distance measuring method, it is characterized in that utilizing the carrier of the polarization characteristic of laser as testing distance information, when the parallel optical axis direction adds half-wave voltage on the single shaft electro-optic crystal, the effect of the polarizing beam splitter in light path, single shaft electro-optic crystal, compensated crystal and polarization analyzer, block rectangular light pulse into pulsewidth t, the then distance L between single shaft electro-optic crystal and the object under test with travelling to and fro between light beam between single shaft electro-optic crystal and the object under test:
Wherein Vc is the aerial speed of light.
Implement the electro light modulation laser distance measuring device of above-mentioned electro light modulation laser distance measuring method, be characterised in that its formation: the laser instrument that comprises an output collimation continuous laser, along the light beam working direction is polarizing beam splitter, single shaft electro-optic crystal, compensated crystal, polarization analyzer successively, and described single shaft electro-optic crystal and compensated crystal thereof are selected onesize rectangular parallelepiped LiNbO for use
3Crystal, side length b＞a=c, and make parallel light b limit pass through crystal, the pair of electrodes sheet is close on the two b * c plane of described single shaft electro-optic crystal, half-wave voltage is added on the single shaft electro-optic crystal perpendicular to the b limit by electrode slice, described polarizing beam splitter play folk prescription to being parallel to each other with the analyzing direction of polarization analyzer or vertical mutually, the vertical placement mutually of the optical axis of single shaft electro-optic crystal and compensated crystal, and the optical axis direction that makes the two all with polarizing beam splitter rise folk prescription to, polarization analyzer analyzing direction is respectively at 45, in the echo reflection direction of polarizing beam splitter one detector is set.
Technique effect of the present invention:
Compare with technology formerly: formerly technology [1] is little short-range measuring method, and along with the increase of measuring distance, precision sharply descends, inapplicable large-scale range observation; The technology formerly [2] [3] [4] that is widely used all needs light signal is converted into analysis and the extraction that electric signal carries out testing distance information, not only in the process that optical problem is converted into electricity question, can introduce unnecessary error, and after being converted into electricity question, increase the complexity of device greatly, introduced the error of many electricity aspect simultaneously again.Compare with technology formerly, the present invention is simple for structure, and is easy to operate, and not affected by environment, antijamming capability is strong, and the measuring distance scope is wide, can survey several meters distance recently, under the energy of lasers condition with higher, can survey the distance of 10 kms farthest.The measuring accuracy height can reach cm-level accuracy.
Description of drawings:
Fig. 1 is the synoptic diagram of basic ideas of the present invention.
Fig. 2 is the structural representation of the principle of the invention.
Fig. 3 is the structure of each device among the present invention and places synoptic diagram.
Embodiment:
The invention will be further described below in conjunction with drawings and Examples.
Basic thought of the present invention as shown in Figure 1, laser instrument is launched a branch of high collimation continuous laser, runs into the object under test back reflection and returns along former road.If can insert a catoptron with optical propagation direction angle at 45 this moment in source ends " instantaneous ", make its reflecting surface towards object under test, then the light that this moment, laser instrument sent is cut off, the light that is reflected by object under test also is cut off, the mirror reversal that is reflected simultaneously is mapped to other direction, the intercepted light beam in two ends forms a rectangular light pulse, and pulse width is t, is light and reflects the required time of catoptron that arrives once more by the catoptron object under test that sets out.Receive this light pulse by detector, try to achieve time t, then can get testing distance L=vct/2, wherein Vc is the aerial velocity of propagation of light.The present invention realizes that above-mentioned " instantaneous " inserts the function of catoptron.
Basic structure of the present invention is shown in Fig. 2,3, as seen from the figure, the electro light modulation laser distance measuring device of the described electro light modulation laser distance measuring method of the invention process, its formation: the laser instrument 1 that comprises an output collimation continuous laser, along the light beam working direction is polarizing beam splitter 2, single shaft electro-optic crystal 3, compensated crystal 5, polarization analyzer 6 successively, and described single shaft electro-optic crystal 3 and compensated crystal 5 thereof are selected onesize rectangular parallelepiped LiNbO for use
3Crystal, side length b＞a=c, and make parallel light b limit pass through crystal, pair of electrodes sheet 4 is close on the two b * c plane of described single shaft electro-optic crystal 3, half-wave voltage is added on the single shaft electro-optic crystal 3 perpendicular to the b limit by electrode slice 4, described polarizing beam splitter 2 play folk prescription to being parallel to each other with the analyzing direction of polarization analyzer 6 or vertical mutually, the vertical placement mutually of the optical axis of single shaft electro-optic crystal 3 and compensated crystal 5, and the optical axis direction that makes the two all with polarizing beam splitter 2 rise folk prescription to, polarization analyzer 6 analyzing directions are respectively at 45, in the echo reflection direction of polarizing beam splitter 2 detector 8 are set.
Wherein the continuous wave laser 1 as light source will have higher energy, to satisfy the demand than telemeasurement.
Said polarizing beam splitter 2 has two effects: the first, and the original emergent light A that laser instrument 1 is launched becomes the polarization direction and plays folk prescription to parallel linearly polarized light B with the polarizer; The second, when folk prescription is played when vertical with the polarizer in the linear polarization light echo F polarization direction that is reflected by object under test, light echo F reflection is departed from original optical path, so that survey.Based on above reason, the polarization beam splitter structure that polarizing beam splitter 2 should select for use crystalline material to make is as structures such as Glan prisms.Polarizing beam splitter 2 is right after laser instrument 1 and is placed on laser instrument 1 bright dipping end, makes its surface of original emergent light A vertical incidence.Polarizing beam splitter 2 rise folk prescription to 2C along coordinate x ' direction among Fig. 3, after random polarized light A injects wherein, be divided into orthogonal two-beam B in polarization direction and W1, pass polarizing beam splitter 2 to the linearly polarized light B of x ' polarization along original optical path along playing folk prescription, linearly polarized light W1 along y ' direction polarization becomes unwanted light, departs from the original optical path outgoing.Simultaneously, when 2 folk prescriptions in light echo F polarization direction that reflects by object under test and polarizing beam splitter when x ' is parallel, light echo F passes polarizing beam splitter 2 along original optical path, when light echo F polarization direction is vertical with x ', light echo F is polarized optical splitter 2 and reflects original optical path, enters detector 8.
Said single shaft electro-optic crystal 3 act as: in conjunction with compensated crystal 5 actings in conjunction, when on single shaft electro-optic crystal 3, adding half-wave voltage V, make successively and reverse 90 ° of angles, thereby make from the linearly polarized light C of compensated crystal 5 outgoing vertical mutually with linearly polarized light B polarization direction from 3 incidents of single shaft electro-optic crystal by the linearly polarized light polarization direction of single shaft electro-optic crystal 3 and compensated crystal 5.Single shaft electro-optic crystal 3 should be selected the uniaxial crystal with transverse electric optical modulation performance for use, and as lithium niobate, lithium tantalate etc., its shape is a rectangular parallelepiped, and physical dimension is a * b * c, wherein b＞c.Do not have between a and the b and be strict with,, consider, should make a=b from the aspect that reduces size and economical with materials because laser facula is circular.Added half-wave voltage V size is proportional to crystalline size and compares a/b on the single shaft electro-optic crystal 3, therefore, obtain lower half-wave voltage V, should select under the condition of minimum length of side a by the ab face smoothly at the satisfied laser facula that allows, make b＞a, but while crystal side length b is subjected to the restriction of gained crystal maximum length as far as possible.Rectangular parallelepiped single shaft electro-optic crystal 3 placement directions make side length b be parallel to coordinate axis z direction, the parallel y direction of length of side a, and the parallel x direction of length of side c impinges perpendicularly on two a * c face linearly polarized light B.Crystal crystalline axis direction 3C chooses the direction along coordinate axis y, places with polarizing beam splitter 2 crystalline axis direction 2C angle at 45, and the while is perpendicular to two b * c plane of single shaft electro-optic crystal 3.Pair of electrodes sheet 4 is attached to respectively on two b * c plane of single shaft electro-optic crystal 3, and size is good just to cover two b * c plane.When making alive on electrode slice 4, the direction of an electric field in the crystal is parallel to crystallographic axis 3C direction.
Said compensated crystal 5 plays the effect that auxiliary single shaft electro-optic crystal 3 is finished modulated polarized light: first, play temperature compensation function, the refractive index of crystal is relatively more responsive to Temperature Influence, particularly when light passed through than the long crystal path, the subtle change of refractive index all can produce a very large impact the phase differential of output o light, e light; Second and single shaft electro-optic crystal 3 one work, when making not on single shaft electro-optic crystal 3 making alive, o light, the e light optical path difference after by these two crystal is zero.Finish above-mentioned effect, compensated crystal 5 should be got and single shaft electro-optic crystal 3 same materials and similar rectangular shape, physical dimension is a ' * b ' * c ', must the long length of side of its long length of side and electro-optic crystal be equated strictness, be b '=b, looser to the requirement of the long a ' of minor face, c ', guarantee that laser beam is smoothly by getting final product, consider that with single shaft electro-optic crystal 3 same factors it is better to get a '=c '.Make the optical axis direction 3C vertical placement mutually of the optical axis direction 5C and the single shaft electro-optic crystal 3 of compensated crystal 5, promptly direction 5C should place along the direction of coordinate x axle, makes laser beam vertically by two a ' * c ' plane simultaneously.
Said polarization analyzer 6 plays and only allows the polarization direction polarized light parallel with its analyzing direction to pass through, stop the effect that the polarization direction polarized light vertical with its analyzing direction passes through, can select any standard polarization analyzing device for use, its structure is not had specific (special) requirements with folk prescription to the analyzing effect.The analyzing optical axis of polarization analyzer 6 has two kinds of laying methods, as solid line 6C direction among Fig. 3 and dotted line 6C ' direction, a folk prescription of direction 6C and polarizing beam splitter 2 is parallel to 2C, promptly with coordinate axis x ' in the same way, a folk prescription of direction 6C ' and polarizing beam splitter 2 is vertical to 2C, promptly with coordinate axis y ' in the same way, direction 6C and 6C ' vertical mutually and respectively with the optical axis direction 3C of single shaft electro-optic crystal 3 and the optical axis direction 5C angle at 45 of compensated crystal 5.
The corresponding two kinds of methods of operating of the present invention of two kinds of displacement structures of polarization analyzer 6 are first kind of method of operating under the situation of placing according to analyzing direction 6C.In this case, making alive on the pair of electrodes sheet 4 of single shaft electro-optic crystal 3 not at first, at this moment, the random polarized light A that laser instrument 1 sends at first impinges perpendicularly in the polarizing beam splitter 2, and polarizing beam splitter 2 is divided into two parts with light beam A: change the polarization direction into and vertically play folk prescription and depart from the original optical path outgoing to the unwanted light W1 of 2C polarization; Change into the polarization direction be parallel to folk prescription to the linearly polarized light B of 2C polarization along the original optical path outgoing.Pass single shaft electro-optic crystal 3 along and then vertical two a of the light beam B * c plane of 2C direction polarization and vertical two a ' * compensated crystal 5 is passed on c ' plane.Because the birefringence effect of crystal, the linearly polarized light B at polarization direction and crystalline axis direction 3C angle at 45 is divided into ordinary light o light and the unusual light e light that energy equates after entering single shaft electro-optic crystal 3, because the vertical optical axis of crystal incident of B, the orthogonal o light in polarization direction and e light are propagated and are not separated along original optical path simultaneously, wherein the optical axis direction 3C of o light polarization direction and single shaft electro-optic crystal 3 is parallel, and e light is vertical with optical axis direction 3C.Crystal is different with the refractive index of e light to o light, different refractive indexes causes between it is gone the same way after light beam B passes single shaft electro-optic crystal 3 two beam split o light and the e light optical path difference being arranged, thereby make two to go the same way between the light beam and to produce a phase differential Г, its occurrence depends on the side length b of electro-optic crystal.Two beam split o light, and then e light enter compensated crystal 5, under the effect of compensated crystal 5, because its optical axis direction 5C is vertical mutually with single shaft electro-optic crystal 3 optical axis direction 3C, after two beam split o light in single shaft electro-optic crystal 3 and e light enter in the compensated crystal 5, o beam split in the former single shaft electro-optic crystal 3 becomes the e beam split of relative compensation crystal 5, e beam split in the former single shaft electro-optic crystal 3 becomes the o beam split with respect to compensated crystal 5, such two beam split produce a phase differential Г ' again after passing compensated crystal 5, and because side length b '=b, this phase differential Г ' and to pass the phase differential Г equal and opposite in direction and the sign of single shaft electro-optic crystal 3 back two beam split opposite, be Г=-Г ', therefore, after linearly polarized light B passes single shaft electro-optic crystal 3 and compensated crystal 5 successively, phase differential is zero between two beam split that its amplitude equates, its synthetic light polarization is constant behind two crystal of outgoing, becomes the linearly polarized light C identical with the B polarization direction.Because the polarization direction of C and the analyzing direction 6C of polarization analyzer 6 are parallel, so linearly polarized light C can pass polarization analyzer 6 insusceptibly and become final emergent light D.Emergent light D shines object under test 7 surfaces after through one section testing distance L and is reflected, become reflected light E, polarization state when light echo E keeps from 6 outgoing of polarization analyzer is constant, along coordinate x ' direction polarization, therefore through and from light beam B to the converse change procedure of light beam D, polarization state is still constant and become along the linearly polarized light F of coordinate axis x ' direction polarization and be injected in the polarizing beam splitter 2.A folk prescription of polarizing beam splitter 2 is to along coordinate axis x ' direction, and parallel with the polarization direction of F, like this, F just can become unwanted light W2 by polarizing beam splitter 2 smoothly.In sum, pass successively and respectively install 2 sending original emergent light A from laser instrument 1,3,4,5,6 arrive object under test 7 surface reflections returns, pass device 6 once more, 5,4,3,2 become in the whole process of unwanted light W2, except random polarized light A isolates the unwanted light W1 in polarizing beam splitter 2, other light beams B, C, D, E, F, W2 is and polarizing beam splitter 2, the linearly polarized light of polarization analyzer 3 optical axis direction parallel polarization, just look like not insert among Fig. 1 under the situation of catoptron in their transmission course, device 2,3,4,5, the propagation of 6 pairs of light is transparent.This is the standby condition before the range finding.
When needs carry out range observation, on the pair of electrodes sheet 4 of single shaft electro-optic crystal 3, add half-wave voltage V.Why being referred to as half-wave voltage, is because under this voltage effect, because the cross electro-optical effect of crystal, vertical crystallographic axis 3C passes between the o light of single shaft electro-optic crystal 3 and e light can increase a phase differential π on the basis of original phase differential Г.The big or small V of half-wave voltage depends on the material and the side ratio a/b of optical maser wavelength, crystal, and size is:
Wherein go into to be optical maser wavelength, n
oAnd n
eBe respectively ordinary refraction index and unusual optical index that single shaft electro-optic crystal 3 corresponding wavelength are gone into, r
13And r
33Two respective components for the crystal electrooptical coefficient.When after adding half-wave voltage V on the single shaft electro-optic crystal 3, owing to increased a phase differential π between amplitude beam split o light and e light to passing waiting in the same way of single shaft electro-optic crystal 3 and compensated crystal 5, this moment is for the linearly polarized light B along coordinate axis x ' direction polarization, single shaft electro-optic crystal 3 and compensated crystal 5 act on the effect of just playing one 1/2 wave plate together, at this moment B passes single shaft electro-optic crystal 3 and compensated crystal 5 rear polarizer directions are reversed 90 ° of angles successively, becomes along the linearly polarized light C of coordinate axis y ' direction polarization.The analyzing direction 6C of the polarization direction of light C and polarization analyzer 6 is vertical mutually, therefore after adding half-wave voltage, the light beam C that penetrates from compensated crystal 5 can not pass through polarization analyzer 6, thus originally unimpeded outgoing beam by from compensated crystal 5 a ' towards polarization analyzer 6 * c ' plane blocked.When adding half-wave voltage, the situation of the light echo E that the light D of our previous again outgoing is reflected by object under test 7: after passing through compensated crystal 5 and the 3 back outgoing of single shaft electro-optic crystal successively along the light echo E of coordinate axis x ' direction polarization originally, become the polarization direction with original vertical and along the linear polarization light echo F of coordinate axis y ' direction polarization, when running into polarizing beam splitter 2, because a folk prescription of the polarization direction of F and polarizing beam splitter 2 is to vertical mutually, light echo F can't pass through along original optical path, divided the polarizing beam splitter 2 of light action to reflex on the pick-up probe 8 on one side by polarizing simultaneously, thereby also original unimpeded reflected light a * c plane of 2 is blocked from single shaft electro-optic crystal 3 towards polarizing beam splitter.In sum, when on single shaft electro-optic crystal 3, adding half-wave voltage V, device 2,3,4,5,6 has just played the effect that " moment " inserts catoptron in light path among Fig. 1: the light path that will travel to and fro between originally between laser instrument 1 and the object under test 7 is blocked, and the light beam section C-D-E-F after will blocking reflexes on the detector 8, forms for the rectangular light pulse G to be measured that measures.Record the pulsewidth t of light pulse G, can obtain testing distance L:
Wherein Vc is the aerial speed of light.
When the analyzing direction of polarization analyzer 6 according to Fig. 3 in the 6C ' direction represented of dotted line place, and during other setting position inconvenience, corresponding second kind of method of operating of the present invention.Under this method of operating, the state that adds half-wave voltage V on the pair of electrodes sheet 4 of single shaft electro-optic crystal 3 is the standby condition before finding range.At this moment, after the linearly polarized light B of polarization direction and single shaft electro-optic crystal 3 crystallographic axis 3C angle at 45 passes through single shaft electro-optic crystal 3 and compensated crystal 5 successively, the polarization direction is reversed 90 ° becomes linearly polarized light C, the polarization direction of linearly polarized light C is just parallel with the analyzing direction 6C ' of polarization analyzer 6 this moment, therefore can become final emergent light D by polarization analyzer 6 smoothly.The light echo E that is reflected by object under test 7 passes through compensated crystal 5 and single shaft electro-optic crystal 3 again after by polarization analyzer 6 successively, 90 ° of folk prescriptions that become polarization direction and polarizing beam splitter 2 are reversed once more to the parallel linearly polarized light F of 2C in its polarization direction, and light F becomes unwanted light W2 by polarizing beam splitter 2 smoothly.As seen, alive the time, device 2,3,4,5,6 similarly is transparent concerning the propagation of laser B, C, D, E, F, W2 on single shaft electro-optic crystal 3.When needs are found range, remove the half-wave voltage V that is added on the single shaft electro-optic crystal 3, device 2,3,4,5,6 is just as the catoptron of " moment " insertion in the light path of Fig. 1 at this moment, a ' towards polarization analyzer 6 * c ' plane is blocked from compensated crystal 5 with emitting light path, the reflected light light path a * c plane of 2 is blocked from single shaft electro-optic crystal 3 towards polarizing beam splitter, light beam section C-D-E-F after will blocking simultaneously reflexes on the detector 8, forms for the rectangular light pulse G to be measured that measures.
Laser instrument 1 is chosen the He-Ne laser instrument of wavelength 632.8nm, and polarizing beam splitter 2 is selected Glan prism for use, and single shaft electro-optic crystal 3 and compensated crystal 5 are all chosen the lithium niobate LiNbO of same size
3, the optical axis that makes single shaft electro-optic crystal 3 is a coordinate y axle, the optical axis of compensated crystal 3 is a coordinate x axle.Device 2,3,5,6 will be chosen suitable volume size, guarantee laser facula can be fully when shining these apparatus surfaces by and energy does not leak.Mutual placement is close in the device unoccupied place of should not leaving a blank between 2,3,4,5,6.When optical maser wavelength is 632.8nm, LiNbO
3Two principal refractive indexs of crystal are n
o=2.2864, n
e=2.2024.
Example 1:
Structure as shown in Figure 3.Single shaft electro-optic crystal 3, compensated crystal 5 are of a size of a * b * c=a ' * b ' * c '=0.2 * 3.4 * 0.2cm
3, pair of electrodes sheet size is as the criterion with two b * c plane that just covers single shaft electro-optic crystal 3, and (aspect ratio is a/b=1 to half-wave voltage V=235V: 17) at this moment.
Claims (2)
1, a kind of electro light modulation laser distance measuring method, it is characterized in that utilizing the carrier of the polarization characteristic of laser as testing distance information, when the parallel optical axis direction adds half-wave voltage on the single shaft electro-optic crystal, the effect of the polarizing beam splitter in light path, single shaft electro-optic crystal, compensated crystal and polarization analyzer, with travelling to and fro between that light beam between single shaft electro-optic crystal and the object under test blocks to pulsewidth is the rectangular light pulse of t, the then distance L between single shaft electro-optic crystal and the object under test:
Wherein Vc is the aerial speed of light.
2, a kind of electro light modulation laser distance measuring device of implementing the described electro light modulation laser distance measuring method of claim 1, be characterised in that its formation: the laser instrument (1) that comprises an output collimation continuous laser, along the light beam working direction is polarizing beam splitter (2), single shaft electro-optic crystal (3), compensated crystal (5), polarization analyzer (6) successively, and described single shaft electro-optic crystal (3) and compensated crystal (5) thereof are selected onesize rectangular parallelepiped LiNbO for use
3Crystal, side length b＞a=c, and make parallel light b limit pass through crystal, pair of electrodes sheet (4) is close on the two b * c plane of described single shaft electro-optic crystal (3), half-wave voltage is added on the single shaft electro-optic crystal (3) perpendicular to the b limit by electrode slice (4), the folk prescription that rises of described polarizing beam splitter (2) is parallel to each other or vertical mutually to the analyzing direction with polarization analyzer (6), the vertical placement mutually of the optical axis of single shaft electro-optic crystal (3) and compensated crystal (5), and the optical axis direction that makes the two all and polarizing beam splitter (2) rise folk prescription to, polarization analyzer (6) analyzing direction is respectively at 45, in the echo reflection direction of polarizing beam splitter (2) detector (8) is set.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2004100930191A CN1308700C (en) | 2004-12-15 | 2004-12-15 | Electro-optical modulation laser distance measuring method and device |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2004100930191A CN1308700C (en) | 2004-12-15 | 2004-12-15 | Electro-optical modulation laser distance measuring method and device |
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| CN1624492A CN1624492A (en) | 2005-06-08 |
| CN1308700C true CN1308700C (en) | 2007-04-04 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TWI730540B (en) * | 2019-12-11 | 2021-06-11 | 精準基因生物科技股份有限公司 | A time-of-flight sensing system and light emitter thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN102278974B (en) * | 2010-06-09 | 2013-04-17 | 南京德朔实业有限公司 | Laser ranging apparatus |
| CN102780524A (en) * | 2012-08-09 | 2012-11-14 | 中国人民解放军国防科学技术大学 | Signal emitter device based on electrodeless ultraviolet communication and method |
| CN103018930A (en) * | 2012-11-25 | 2013-04-03 | 华中科技大学 | High-speed shutter device and application thereof |
| CN103398983B (en) * | 2013-08-01 | 2015-07-15 | 合肥知常光电科技有限公司 | Polarization measurement method for wrapping edge interface residual reflection of laser gain medium |
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| US3900246A (en) * | 1971-05-24 | 1975-08-19 | Nippon Electric Co | Lanthanum titanate single crystal electro-optic modulator |
| JPS5243372B1 (en) * | 1971-05-24 | 1977-10-29 | ||
| CN1123573A (en) * | 1993-05-15 | 1996-05-29 | 莱卡公开股份有限公司 | Device for measuring distance |
| US5734263A (en) * | 1996-02-06 | 1998-03-31 | Eaton Corporaton | Electro-optic voltage transducer with extended range and temperature compensation |
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| US3900246A (en) * | 1971-05-24 | 1975-08-19 | Nippon Electric Co | Lanthanum titanate single crystal electro-optic modulator |
| JPS5243372B1 (en) * | 1971-05-24 | 1977-10-29 | ||
| CN1123573A (en) * | 1993-05-15 | 1996-05-29 | 莱卡公开股份有限公司 | Device for measuring distance |
| US5734263A (en) * | 1996-02-06 | 1998-03-31 | Eaton Corporaton | Electro-optic voltage transducer with extended range and temperature compensation |
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| 一种新的高精度测相方法 古平北，光电工程，第22卷第5期 1995 * |
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| TWI730540B (en) * | 2019-12-11 | 2021-06-11 | 精準基因生物科技股份有限公司 | A time-of-flight sensing system and light emitter thereof |
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