CN1245618C - Apparatus and method for measuring distance measuring capability of laser altimeter/distance finder - Google Patents

Abstract

The present invention relates to a device for measuring the distance measuring capability of a laser altimeter. The present invention is characterized in that the device is composed of a transmitting-reflecting mirror, a reflecting mirror, an attenuater, a simulated target, an energy meter and a waveform display system, wherein the transmitting-reflecting mirror, the reflecting mirror, the attenuater and the simulated target are orderly arranged in traveling direction of a laser beam emitted from a laser emitting system of a laser altimeter; the energy meter is arranged in the transmitting direction of the transmitting-reflecting mirror; the transmitting-reflecting mirror and the laser beam have an angle of 45 degrees, and the reflecting mirror and the laser beam have an angle of 45 degrees; the transmitting-reflecting mirror and the reflecting mirror are used for deflecting the laser beam emitted from the laser altimeter so that the laser beam is coaxial with a laser receiving system of the laser altimeter. The present invention has the advantages of simple device, convenient operation, indoor test, no external environmental influence, high measuring precision, etc.

Description

The equipment and the method for Laser Measurement altimeter/stadimeter range capability

Technical field

The present invention relates to the measurement of laser ceilometer and laser range finder performance parameter, particularly a kind of equipment and method that is used for Laser Measurement altimeter/stadimeter range capability.

Background technology:

Laser ceilometer and laser range finder (hereinafter to be referred as laser ceilometer) are formed by laser transmitting system and laser receiver system, and its performance is meant its range capability to a great extent, promptly maximum ranging.Particularly concerning remote laser ceilometer (more than the 20km), maximum ranging index is particularly important.Owing to be subjected to the influence of various factors, on ground the target that is positioned at maximum ranging distance to be surveyed and unrealistic, its result's degree of accuracy also is not high.

Extinction coefficient method is one of method of the maximum ranging of traditional experimental determination laser ceilometer.Though this method also needs operation in the open air, and be different from open-air actual measurement.The specific implementation process of extinction coefficient method is: place a diffuse reflector at distance laser ceilometer 0.5km place, open laser instrument, emitted laser is got on the diffuse reflector.Place optical filter in the receiving system front, reduce to arrive the laser energy in the receiving system.The transmitance of optical filter is predefined, in the operating process of reality, according to circumstances transmitance is done the adjusting of trace again.Transmitance when laser ceilometer has correct range reading is exactly its sensitivity.Can obtain maximum ranging according to sensitivity.When calculating maximum ranging, also need know the atmospheric visibility when measuring.The can yet be regarded as method of maximum ranging of a kind of principle and the simple Laser Measurement altimeter of equipment of extinction coefficient method.But,, higher to the experiment site requirements owing to this method can only realize in the open air.Simultaneously, it is bigger influenced by atmospheric conditions, therefore, is difficult to obtain higher degree of accuracy.

The method of optical fiber simulation target range by the circle transmission of laser in optical fiber, can be simulated the target of different distance, realizes different laser ceilometers are measured.Because the diameter of laser beam is far longer than the diameter of optical fiber, need the design optical system that laser beam is coupled, so the checkout equipment light path complexity of the type, and the optical axis alignment difficulty, simultaneously, the difficult time-delay of measuring optical fiber.

In conjunction with the means of electronics and software, the method for Laser Measurement altimeter range capability needs to use Laser Simulator.The simulated laser device is used to produce analogue echo.Concrete approach is: by way of hardware and software combination, change the performance of the inside components and parts of Laser Simulator, thereby obtain the adjustable simulated laser bundle of performance parameter, simulation is when reality is found range, and external environment is to the influence of emission of lasering beam.With respect to the time-delay between the emission laser, can simulate different target ranges by delay circuit control Laser Simulator.

Summary of the invention:

The technical problem to be solved in the present invention is to overcome the difficulty of above-mentioned prior art, and the equipment and the method for the maximum ranging of a kind of Laser Measurement altimeter/stadimeter range capability is provided, and this equipment should be simple, and measuring method is simple and effective.

The maximum ranging of laser ceilometer is certain relatively condition.Under different atmospheric conditions, the object of different surfaces characteristic to be found range, the maximum ranging that obtains is inequality.Therefore, during not only to the object range finding of the same character of surface that is in different distance, Laser emission energy difference; To same distance, the range finding of different surfaces characteristic object the time, required Laser emission energy is also different.Corresponding these different range finding conditions, in the receiving system of laser ceilometer, the minimum detectable power of sounder is constant.Be that the minimum echo energy of response is arranged is certain value to receiving system.Therefore, the value of each parameter of correspondence when reaching the minimum detectable performance number, the maximum ranging in the time of can extrapolating the laser ceilometer range finding according to laser ceilometer.

Concrete technical scheme of the present invention is as follows:

A kind of equipment of Laser Measurement altimeter range capability, it is characterized in that its formation is: the laser beam working direction of sending along the laser transmitting system of this laser ceilometer comprises anti-mirror, catoptron, attenuator, simulated target successively, is provided with energy meter in the transmission direction of saturating anti-mirror; Saturating anti-mirror and laser beam are at 45, described catoptron is positioned on the reflected light direction of described anti-mirror, catoptron and laser beam are at 45, and the effect of the two is that the laser beam that laser ceilometer is sent is turned back, make it coaxial with the laser receiver system of laser ceilometer, also have the waveform display system, this waveform display system is connected with described laser receiver system, is used to show the echo digital signal.

Described attenuator is made of attenuator support and the attenuator group that includes the polylith attenuator, and the attenuator support has a plurality of attenuator sockets, plugs for this attenuator.

Described simulated target is the known reflecting plate of surface reflectivity.

Use the method for the equipment of above-mentioned Laser Measurement altimeter range capability, comprise the following steps:

1.. laser ceilometer is docked with measuring equipment, making the angle of optical axis of the laser transmitting system of anti-mirror and laser ceilometer is 45 °, angle between the optical axis of the laser receiver system of catoptron and laser ceilometer also is 45 °, and ensures the laser beam after mirror reflects and the light shaft coaxle of this laser receiver system;

2.. certain distance Rs is provided with simulated target on the laser beam working direction;

3.. the energy of emission of lasering beam monopulse is made as certain value, is Wo by the energy meter monitoring;

4.. increase the attenuator of attenuator, monitor the digital signal of return laser beam simultaneously by the laser receiver system of laser range finder, when the echo digital signal is 0, write down the transmitance τ o of attenuator;

5.. utilize following formula to calculate the maximum ranging of laser ceilometer:

${\mathrm{<figure-callout\; id="2"\; label="R\; max"\; filenames="C20031010872400101.png"\; state="\{\{state\}\}">R</figure-callout>}}_{\max }^{}=\frac{W_t\&CenterDot;{\mathrm{\&rho;}}_{\mathrm{tar}}\&CenterDot;\cos \mathrm{\&alpha;}\&CenterDot;{\mathrm{\&tau;}}_a^2}{W_{\mathrm{ts}}\&CenterDot;{\mathrm{\&rho;}}_{\mathrm{tars}}\&CenterDot;{\cos \mathrm{\&alpha;}}_s\&CenterDot;{\mathrm{\&tau;}}_{\mathrm{as}}^2}\&CenterDot;{\mathrm{<figure-callout\; id="2"\; label="R\; s"\; filenames="C20031010872400101.png"\; state="\{\{state\}\}">R</figure-callout>}}_s^{}$

In the formula:

W _TsThe monopulse laser energy of=Wo τ o-laser ceilometer minimum detectable

The monopulse laser energy of the emission that the Wo-energy meter detects

When τ o-is 0 when the echo digital signal, the transmitance of attenuator

The monopulse maximum laser energy of Wt-laser ceilometer emission

ρ _TarThe surface reflectivity of-object

ρ _Tars-simulated target surface reflectivity

α-laser is to the incident angle on object surface

α s-laser is to the incident angle on simulated target surface

τ ² _a-laser ceilometer is to the atmosphere round trip transmitance of surveying target

τ ² _As-laser ceilometer is to the atmosphere round trip transmitance of simulated target

The Rs-laser ceilometer is to the distance between the simulated target

Advantage of the present invention is: measuring equipment is simple, and measuring method is easy; Saturating anti-mirror 1 adopts the half-reflection and half-transmission sheet, and energy meter can be realized measuring in real time to the Laser emission energy; Adopt emission laser two secondary reflections to turn back, guarantee that the emission of laser is coaxial with reception, laboratory experiment is not affected by the external environment; Adopt the diffuse reflection simulated target, during the actual range finding of real simulation, target is to the reflection of laser.

Description of drawings:

Fig. 1 is the equipment of Laser Measurement altimeter range capability of the present invention and the synoptic diagram of the state of measurement thereof.

Fig. 2 is the structural representation of attenuator of the present invention.

Embodiment:

See also Fig. 1, Fig. 2 earlier, Fig. 1 is the equipment of Laser Measurement altimeter range capability of the present invention and the synoptic diagram of the state of measurement thereof, and Fig. 2 is the structural representation of attenuator.As seen from the figure, the equipment of Laser Measurement altimeter range capability of the present invention comprises: saturating anti-mirror 1, catoptron 2, energy meter 3, attenuator 4, simulated target 5, waveform display system 6 with certain transmission.Saturating anti-mirror 1 and catoptron 2 are turned back the laser that the laser transmitting system 71 of laser ceilometer 7 is sent coaxial with laser receiver system 72.Saturating anti-mirror 1 is semi-transparent semi-reflecting, and catoptron 2 is the total reflection sheet.Energy meter 3 is used for the energy of the laser beam that Laser Measurement emission coefficient 71 sent.Attenuator 4 is made up of attenuator support 41 and attenuator group 42.Whole attenuator 4 be used to the to decay energy of emission laser.Described attenuator support 41 has a plurality of attenuator sockets 411, and attenuator group 42 is made up of the attenuator 421 with different transmitances, by changing the composition of attenuator group 42, can obtain the attenuator 4 of different transmitances.Simulated target 5 is surface reflectivity ρ _TarsKnown reflecting plate is followed Lambert's law of reflection to the reflection that incident laser produces, when can be used for the simulated laser altimeter real goal being found range, by the diffuse reflection that target produced.Waveform display system 6 uses oscillograph to realize, is used to monitor echoed signal.See Fig. 1.

Utilize the method for the maximum ranging of the said equipment Laser Measurement altimeter, comprise the following steps:

A. laser ceilometer 7 is docked with measuring equipment, making the angle between anti-mirror 1 and laser transmitting system 71 optical axises is 45 °, and the angle between catoptron 2 and laser receiver system 72 optical axises also is 45 °.Guarantee through laser beam and laser receiver system 72 same optical axises after catoptron 2 reflections;

B. simulated target 5 is arranged in the light path, and regulates distance between simulated target 5 and the laser ceilometer 7 as required, distance to be being advisable less than 50m greater than 20m, and uses the definite distance R s between classic method measure analog target 5 and the laser ceilometer 7;

C. laser transmitting system 71 emitted laser energy are made as certain value Wo, change the composition of attenuator 4, to obtain different transmitances, use waveform display system 6 to show laser receiver system 72 resultant echo digital signals, shown energy value Wo in the transmitance τ o of the attenuator 4 that record is corresponding when digital echo signal disappears and the energy meter 3, promptly the time to simulated target 5 range finding of given distance R s, required laser energy Wo.At this moment, the power of pairing sounder is exactly laser ceilometer minimum detectable power Wo τ o.

D. by the corresponding relation between maximum ranging and each parameter, calculate the maximum ranging of the laser ceilometer 7 under specified criteria.

The maximum ranging of laser ceilometer is represented by following formula:

${\mathrm{<figure-callout\; id="2"\; label="R\; max"\; filenames="C20031010872400101.png"\; state="\{\{state\}\}">R</figure-callout>}}_{\max }^{}=\frac{W_t\&CenterDot;{\mathrm{\&rho;}}_{\mathrm{tar}}\&CenterDot;\cos \mathrm{\&alpha;}\&CenterDot;{\mathrm{\&tau;}}_a^2}{W_{\mathrm{ts}}\&CenterDot;{\mathrm{\&rho;}}_{\mathrm{tars}}\&CenterDot;{\cos \mathrm{\&alpha;}}_s\&CenterDot;{\mathrm{\&tau;}}_{\mathrm{as}}^2}\&CenterDot;{\mathrm{<figure-callout\; id="2"\; label="R\; s"\; filenames="C20031010872400101.png"\; state="\{\{state\}\}">R</figure-callout>}}_s^{}$

In the formula:

W _TsThe monopulse laser energy of=Wo τ o-laser ceilometer minimum detectable

The monopulse laser energy of the emission that Wo-energy meter (3) detects

When τ o-is 0 when the echo digital signal, the transmitance of attenuator (4)

The maximum monopulse laser energy of Wt-laser ceilometer (7) emission

ρ _TarThe surface reflectivity of-object

ρ _Tars-simulated target (5) surface reflectivity

α-laser is to the incident angle on object surface

α s-laser is to the incident angle on simulated target (5) surface

τ ² _a-laser ceilometer (7) is to the atmosphere round trip transmitance of surveying target

τ ² _As-laser ceilometer (7) is to the atmosphere round trip transmitance of simulated target (5)

Rs-laser ceilometer (7) is to the distance between the simulated target (5).

Claims (4)

1, a kind of equipment for measuring the distance measuring ability of laser altimeter, it is characterized in that its composition is: along the laser beam advancing direction that the laser emission system (71) of this laser altimeter (7) sends successively comprises mirror ( 1), reflecting mirror (2), attenuator (4), analog target (5), are provided with energy meter (3) in the transmission direction of transflector (1); Transflector (1) and laser beam form 45 °, the reflector (2) is positioned at the reflected light direction of the lens (1), the reflector (2) is 45° with the laser beam, and the effect of the two is to place the laser altimeter (7 ) the laser beam deflection that sends, makes it coaxial with the laser receiving system (72) of laser altimeter (7); There is also waveform display system (6), and this waveform display system (6) and described laser A receiving system (72) is connected for displaying the echo digital signal. 2. The device for measuring the ranging capability of a laser altimeter according to claim 1, characterized in that the attenuator (4) consists of an attenuation sheet bracket (41) and an attenuation sheet comprising a plurality of attenuation sheets (421). The sheet group (42) is formed, and the attenuation sheet support (41) has a plurality of attenuation sheet sockets (411), for the attenuation sheet (421) to be inserted. 3. The device for measuring the distance measuring capability of a laser altimeter according to claim 2, characterized in that the simulated target (5) is a reflective plate with a known surface reflectivity. 4. A method of using the device for measuring the range-finding capability of a laser altimeter as claimed in claim 1, comprising the following steps: 1. The laser altimeter (7) is docked with the measuring equipment, so that the included angle of the optical axis of the laser emitting system (71) of the mirror (1) and the laser altimeter (7) is 45 °, and the reflector ( 2) The included angle with the optical axis of the laser receiving system (72) of the laser altimeter (7) is also 45 °, and guarantees that the laser beam reflected by the reflector (2) and the laser receiving system (72) The optical axis is coaxial; ②. Set a simulated target (5) at a certain distance Rs in the direction of laser beam advancement; ③. The energy of the single pulse of the emitted laser beam is set to a certain value, which is monitored by the energy meter (3) as Wo; ④. Increase the attenuation sheet (421) of the attenuator (4), and monitor the digital signal of the laser echo by the laser receiving system (72) of the laser rangefinder (7) at the same time, when the echo digital signal is 0, write down The transmittance τo of the attenuator (4); 5. Utilize the following formula to calculate the maximum range _Rmax of the laser altimeter (7): ${\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; max</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; t</span>}}<span\; class="notranslate">\; \&CenterDot;</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; tar</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}\mathrm{<span\; class="notranslate">\; \&alpha;</span>}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; a</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}{{\mathrm{<span\; class="notranslate">\; W</span>}}_{\mathrm{<span\; class="notranslate">\; ts</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; \&rho;</span>}}_{\mathrm{<span\; class="notranslate">\; tars</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>\mathrm{<span\; class="notranslate">\; cos</span>}{\mathrm{<span\; class="notranslate">\; \&alpha;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; \&tau;</span>}}_{\mathrm{<span\; class="notranslate">\; as</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; \&Center\; Dot;</span>{\mathrm{<span\; class="notranslate">\; R</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}$ In the formula: W _ts ＝Woτo—the minimum detectable single-pulse laser energy of the laser altimeter Wo—the emitted single-pulse laser energy detected by the energy meter (3) τo—When the echo digital signal is 0, the transmittance of the attenuator (4) Wt—the maximum single-pulse laser energy emitted by the laser altimeter (7) ρ _tar — surface reflectance of the target ρ _tars — surface reflectivity of simulated target (5) α—the incident angle of the laser on the surface of the target αs—the incident angle of the laser on the surface of the simulated target (5) τ ² _a —Atmospheric two-way transmittance from the laser altimeter (7) to the measured target τ ² _as —Atmospheric two-way transmittance from the laser altimeter (7) to the simulated target (5) Rs—the distance between the laser altimeter (7) and the simulated target (5).

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