CN1595196A - Optical calibrating apparatus and method of laser ranging system - Google Patents

Abstract

It is a laser distance-finding system optics calibration apparatus which comprises receiving optics system and laser and is characterized by the following: there is located with a receiving angular field stimulate laser in front of the receiving optics system; there is located with parallel light tube at the back of the receiving optics system and the laser; there is located with a image screen vertical to its main axis behind the parallel light tube; there is a surface array CCD behind the image screen which is connected with computer; The output end RS322 serial port and laser are connected with the receiving angular field stimulate laser outer trigger power.

Description

Laser distance measuring system optical alignment means and method

Technical field:

The present invention relates to laser ranging, particularly a kind of laser distance measuring system optical alignment means and method.

Background technology:

The earth observation laser distance measuring system is by the development of airborne laser height-finding technique, and following of realization machine is surveyed height in early days, and precision is relatively poor.Because popularizing of GPS technology, measuring accuracy improves rapidly.

The basic functional principle of laser distance measuring system is: the distance that light is passed by during obtaining by the mistiming of measuring emission laser and reception return laser beam, and then obtain distance value.

The performance of laser ceilometer/stadimeter is meant its range capability to a great extent, promptly maximum ranging.For remote laser ceilometer/stadimeter (more than the 20km), maximum ranging index is particularly important, has directly determined the use height/distance and the efficiency of measurement of this type systematic.

System must manufacture and design according to maximum ranging.According to maximum ranging formula

$Z_{\max }=\sqrt{\frac{P_T{S}_r{T}_T{T}_{R}A\left(z\right)\mathrm{\σ}\cos \mathrm{\θF}}{\mathrm{\π}{P}_{r\min }}}---\left(1\right)$

Z _Max: maximum ranging, P _T: emissive power, S _r: receiving area, T _T: emission coefficient optical transmittance, T _R: the receiving system optical transmittance, A (z): round trip propagation in atmosphere transmitance, σ: terrain object reflectivity, F are the central transmitance of optical filter, P _Rmin: I is surveyed power input, and θ is the incident angle on the relative object of emitted laser bundle surface.

Be at emission center, visual field and receive the maximum ranging of range measurement system under the perfect condition that the center, visual field overlaps fully by what this formula obtained.Under the constant situation of other condition, emissive power that can be by improving laser is to improve the maximum ranging of system.But under actual conditions, the coaxial precision that Laser emission and return laser beam receive is also depended in the maximum ranging of system.Deviation between the two can make the maximum ranging of range measurement system less than the above-mentioned theory value, and when deviation angle is excessive, system even can't find range.Improve the registration at emission center, visual field and reception center, visual field, become the key factor that improves system capability.In practice utilization, the calibration that receives center, visual field and emission center, the visual field most important factor of ranging that has the greatest impact often.The preliminary coincidence of structure and optical design principal security visual field, the precision adjustment of visual field registration is mainly guaranteed by optical alignment.

In traditional method, generally adopt parallel light tube to carry out optical alignment.Basic skills is: with the sounder in the laser instrument replacement range measurement system, its light beam of launching simulation receives visual field.Utilize parallel light tube the parallel beam of different directions to be focused on the character of the diverse location on the focal plane, the outgoing beam of range measurement system and the reception visual-field beam of simulation are focused on, whether overlap by the center of observing two pictures, judge whether the reception visual field is parallel with the central shaft of emission visual field.Greatest problem in the classic method is that optical correction work judges the coincidence degree of emission visual field and reception visual field by staff's optical imagery effect that detects by an unaided eye fully, it is bigger influenced by subjective factor, can not provide the coincidence degree that transmits and receives the visual field quantitatively, make the precision of optical alignment limited.

Summary of the invention:

The objective of the invention is to overcome above-mentioned the deficiencies in the prior art, a kind of laser distance measuring system optical alignment means and method are provided, it can provide emission center, visual field quantitatively and receive the registration at center, visual field, to realize that the high-precision optical correction of laser distance measuring system is improved the maximum ranging of laser distance measuring system to greatest extent.

Technical solution of the present invention is as follows:

A kind of laser distance measuring system optical alignment means, comprise receiving optics and laser instrument, it is characterized in that establishing reception visual field simulated laser device before this receiving optics, after receiving optics and laser instrument, be parallel light tube, establish a picture screen perpendicular to its main shaft after this parallel light tube, behind this picture screen is area array CCD, and this area array CCD links to each other with computing machine, and this fanout RS322 serial ports connects laser instrument and receives the external trigger source interface of visual field simulated laser device.

Exit end at this reception visual field simulated laser device is equipped with the first absorption optical filter, and the output terminal of described laser instrument has the second absorption optical filter.

With above-mentioned optical alignment means laser distance measuring system is carried out the method for optical correction, it is characterized in that comprising the following steps:

1.. computing machine sends signal to laser instrument, reception visual field simulated laser device and area array CCD respectively, to realize synchronous working;

2.. area array CCD is gathered the emission visual field and is received the visual field light spot image from the picture screen, sends into computing machine and carries out data processing, and show on computer screen;

3.. the light spot image that picture is shielded monitors and analyzes, and simultaneously laser distance measuring system is adjusted, and implements slightly calibration;

4.. when emission center, visual field and the excentricity that receives the center, visual field less than 1/10 the time, computing machine carries out data processing by the barycenter statistic law, laser distance measuring system is carried out essence calibration, reach designing requirement up to emission center, visual field with reception center, visual field or overlap fully.

The process of described smart calibration is as follows:

A. utilize the method for tabling look-up that image is carried out dark current correction and radiant correction;

B. use the barycenter statistic law to calculate the center of emission visual field hot spot and reception visual field hot spot, obtain its brightness value; And with the 1/e of its brightness value ²The threshold values that uses when being made as the actuarial barycenter;

C. ignore the picture element of brightness value, brightness value in the image is reused the barycenter that the barycenter statistic law calculates hot spot greater than the picture element of threshold values, and calculate the diameter of hot spot simultaneously less than threshold values;

D. calculate excentricity, represent to launch the registration of visual field and reception visual field with excentricity quantitatively.

Technique effect of the present invention:

1. utilize apparatus of the present invention that laser distance measuring system is carried out optical correction, directly perceived, high efficiency;

2. apparatus of the present invention are handled through ccd image collection and computer data, can obtain the center, emission visual field and the deviation that receives the center, visual field of laser distance measuring system quantitatively at any time, guiding optics calibration in real time, and make it to reach design standards, even overlap the calibration accuracy height fully.

3. be provided with absorption optical filter in apparatus of the present invention, can protect the safety of ccd detector, in order to avoid supersaturation influences image quality, the absorption of regulating this optical filter can obtain high-quality light spot image.

Description of drawings:

Fig. 1 is the structural representation of laser distance measuring system optical alignment means of the present invention.

Fig. 2 is the process flow diagram that apparatus of the present invention are carried out optical correction.

Embodiment:

See also Fig. 1 earlier, Fig. 1 is the structural representation of laser distance measuring system optical alignment means of the present invention, this shows, laser distance measuring system optical alignment means of the present invention

A kind of laser distance measuring system optical alignment means, comprise receiving optics 3 and laser instrument 4, it is characterized in that establishing reception visual field simulated laser device 1 before this receiving optics 3, after receiving optics 3 and laser instrument 4, be parallel light tube 6, establish picture screen 7 perpendicular to its main shaft after this parallel light tube 6, behind this picture screen 7 is area array CCD 8, and this area array CCD 8 links to each other with computing machine 9, and the external trigger source of these computing machine 9 output terminal RS322 serial ports and laser instrument 4 and reception visual field simulated laser device 1 joins.The course of work of apparatus of the present invention is as follows:

The absorption optical filter of laser beam process 2 backs that A, reception visual field simulated laser device 1 send enter parallel light tube 5 by receiving optics 3, converge at last as shielding to simulate on 7 and receive visual field 52; The laser beam that ranging laser 4 sends is by absorption optical filter 5, enters to converge in picture screen 7 behind the parallel light tube 6 and form emission visual fields 51.

Laser facula on B, 8 pairs of picture screens 7 of area array CCD is surveyed and imaging.Excessive for preventing the shoot laser energy, cause imaging CCD8 pixel satiety and cause image deformation, should regulate the attenuation coefficient of the first absorption attenuator 2 and the second absorption attenuator 5 as one sees fit.The photosurface that should note CCD8 when obtaining image is vertical with the central shaft that receives the visual field with the central shaft of emission visual field, otherwise the image that will obtain being out of shape influences data analysis.The view data that CCD8 obtains is input in the computing machine 9.

C, utilize optical alignment means of the present invention that laser distance measuring system is carried out the method for optical correction, comprise the following steps:

Computing machine 9 sends signal to laser instrument 4, reception visual field simulated laser device 1 and area array CCD 8 respectively, to realize synchronous working;

Area array CCD is gathered emission visual field 51 and the light spot image that receives visual field 52 from picture screen 7, sends into computing machine 9 and carries out data processing, and show on the display screen of computing machine 9;

Light spot image is monitored and analyzes, simultaneously laser distance measuring system is calibrated;

When emission center, visual field and the excentricity that receives the center, visual field less than 1/10 the time, computing machine 9 carries out data processing by the barycenter statistic law, and laser distance measuring system carried out essence calibration, reach designing requirement up to emission center, visual field with reception center, visual field or overlap fully.

Apparatus of the present invention are carried out the flow process of optical correction shown in 2 to laser distance measuring system.After computing machine 9 was started working, initialization also started image capture device, showed greater than 1/10 o'clock that in excentricity adopt thick calibration mode, excentricity enters smart calibration mode after 1/10.

Under thick calibration mode, computing machine 9 is gathered the imaging of CCD8 in real time, and uses the barycenter statistic algorithm to calculate the center (x that transmits and receives the visual field hot spot with certain frequency to a frame image data _c, y _c) and excentricity.The formula of barycenter statistic algorithm is:

$x_c=\frac{\underset{x=1}{\overset{N}{\mathrm{\Σ}}}\underset{y=1}{\overset{N}{\mathrm{\Σ}}}\mathrm{xg}(x,y)}{\underset{x=1}{\overset{N}{\mathrm{\Σ}}}\underset{y=1}{\overset{N}{\mathrm{\Σ}}}g(x,y)}$ $y_c=\frac{\underset{x=1}{\overset{N}{\mathrm{\Σ}}}\underset{y=1}{\overset{N}{\mathrm{\Σ}}}\mathrm{yg}(x,y)}{\underset{x=1}{\overset{N}{\mathrm{\Σ}}}\underset{y=1}{\overset{N}{\mathrm{\Σ}}}g(x,y)}$

X wherein, y is respectively horizontal stroke, the ordinate of picture element; (x is (x, the brightness value of picture element y) for coordinate figure y) to g.

Adopt the barycenter statistic algorithm can reduce the influence of the light intensity fluctuation of LASER Light Source own, increase the stability of result of calculation, and not strict during perpendicular to beam direction at the CCD8 photosurface, result of calculation more approaches the subpoint of visual field central shaft than the geometric center of simply asking hot spot.

Under smart calibration mode, monitoring of software stops being seen real time imagery of CCD8 and data processing.After being carried out dark current correction and radiant correction, select for use image the shooting quality better image to adopt several integral method denoisings.The result of calculation that the spot diameter of reception visual field calculates excentricity has a significant impact.The light that reception used herein visual field simulated laser device sends is mainly basic mode, and the laser facula basic mode size is defined as:

$\mathrm{\&omega;}=\mathrm{\&omega;}{|}_{I=I_0/{\mathrm{<figure-callout\; id="2"\; label="e"\; filenames="A20041002563200111.png"\; state="\{\{state\}\}">e</figure-callout>}}^2}$

Promptly defining brightness is laser facula center brightness 1/e ²The position be the hot spot edge.According to the first center of using centroid algorithm to estimate to calculate two hot spots of this definition, obtain its brightness value, the 1/e of its brightness value ²The threshold value of using during for the actuarial barycenter.Ignore the picture element of brightness value, brightness value in the image is reused the barycenter of barycenter statistic algorithm actuarial glossing up greater than the picture element of threshold value, and calculate the diameter of hot spot simultaneously less than threshold value.Can obtain the center of hot spot comparatively accurately with this barycenter statistic algorithm that has preanalysis.Simultaneously, by the preanalysis of data, can obtain the diameter that receives the visual field hot spot comparatively accurately.Both all help improving the computational accuracy of excentricity, thereby realize high-precision optical correction.

Consider the needs of real-time monitoring under the thick calibration mode, data are not carried out dark current correction and radiant correction, also do not adopt the barycenter statistic algorithm that has preanalysis, only data are carried out disposable analysis obtains the facula mass center position.

In sum, the process of the smart calibration of the present invention can be summarized as follows:

1.. utilize the method for tabling look-up that image is carried out dark current correction and radiant correction;

2.. use centroid algorithm to calculate the center of two hot spots, obtain its brightness value; And with the 1/e of its brightness value ²The threshold values that uses when being made as the actuarial barycenter;

3.. ignore the picture element of brightness value, brightness value in the image is reused the barycenter of barycenter statistic algorithm actuarial glossing up greater than the picture element of threshold values, and calculate the diameter of hot spot simultaneously less than threshold values;

4.. calculate excentricity, with excentricity quantitative expression emission visual field and the registration that receives the visual field.

Compared with the prior art, the present invention has outstanding substantive distinguishing features and significant technical progress.Owing to adopted the method for software and hardware combining, made whole optical alignment means more be tending towards completeization.Use by this device, the operating personnel's of optical correction working strength reduces greatly, simultaneously owing to adopt excentricity to represent the visual field registration quantitatively, eliminated the subjective error that eye-observation brings, the use that cooperates high pixel to count image capture device, greatly improve the precision of optical correction, shortened the time of optical correction.This device adopts mode initiatively to obtain light spot image, has avoided range measurement system emission laser and optical alignment means to obtain the asynchronous of image time.

Claims (4)

1, a kind of laser distance measuring system optical alignment means, comprise receiving optics (3) and laser instrument (4), it is characterized in that this receiving optics (3) is established before receives visual field simulated laser device (1), in receiving optics (3) and laser instrument (4) is parallel light tube (6) afterwards, this parallel light tube (6) is established picture screen (7) perpendicular to its main shaft afterwards, behind this picture screen (7) is area array CCD (8), this area array CCD (8) links to each other with computing machine (9), and the external trigger source of this computing machine (9) output terminal RS322 serial ports and laser instrument (4) and reception visual field simulated laser device (1) joins.

2, optical alignment means according to claim 1 is characterized in that: the exit end at this reception visual field simulated laser device (1) is equipped with the first absorption optical filter (2), and the output terminal of described laser instrument (4) has the second absorption optical filter (5).

3, optical alignment means according to claim 1 and 2 is carried out the method for optical correction to laser distance measuring system, it is characterized in that comprising the following steps:

1.. computing machine (9) sends signal to laser instrument (4), reception visual field simulated laser device (1) and area array CCD (8) respectively, to realize synchronous working;

2.. area array CCD (8) is gathered emission visual field (51) and is received visual field (52) light spot image from picture screen (7), sends into computing machine (9) and carries out data processing, and show on the display screen of computing machine (9);

3.. to monitoring as the light spot image on the screen (7) and analyzing, simultaneously laser distance measuring system is adjusted, implemented slightly calibration;

4.. when emission center, visual field and the excentricity that receives the center, visual field less than 1/10 the time, computing machine (9) carries out data processing by the barycenter statistic law, laser distance measuring system is carried out essence calibration, reach designing requirement up to emission center, visual field with reception center, visual field or overlap fully.

4, optical standard method according to claim 3 is characterized in that the process of described smart calibration is as follows:

A. utilize the method for tabling look-up that image is carried out dark current correction and radiant correction;

B. use the barycenter statistic law to calculate the center of emission visual field hot spot and reception visual field hot spot, obtain its brightness value; And with the 1/e of its brightness value ²The threshold values that uses when being made as the actuarial barycenter;

C. ignore the picture element of brightness value, brightness value in the image is reused the barycenter that the barycenter statistic law calculates hot spot greater than the picture element of threshold values, and calculate the diameter of hot spot simultaneously less than threshold values;

D. calculate excentricity, represent to launch the registration of visual field and reception visual field with excentricity quantitatively.

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