CN104391291A - Fine particle laser radar system with adjustable focal position and self-calibration method - Google Patents

Abstract

The invention provides a fine-particle laser radar system with adjustable focus position and a self-calibration method, including a laser, an imaging CCD, a control computer, a beam expander (8), a first right-angle reflective prism (9), and an angle reflector (10 ), plane mirror (11), collimating mirror (12) and the second right-angle reflecting prism (13); (11), corner reflector (10), receiving optical system, collimating mirror (12), the second right-angle reflective prism (13) arrive at the imaging CCD after, the imaging CCD connects the control computer, and the control computer controls the laser. The adjustment of the position of the primary mirror in the present invention realizes the adjustment of the focal plane and the focus position, and realizes a whole set of debugging process of the fine-particle laser radar system from rough adjustment to fine adjustment. This method replaces artificial calibration and non-target images as reference points, improves accuracy and eliminates human errors caused by human operations.

Description

A focus position adjustable fine particle laser radar system and self-calibration method

technical field

The invention relates to an adjustable focus position and high-precision calibration method in a fine-particle laser radar system, belonging to the field of laser radar.

Background technique

Fine particle lidar can monitor parameters such as atmospheric aerosol backscattering coefficient, atmospheric extinction coefficient, atmospheric particle mass concentration, and atmospheric boundary layer height in real time. Atmospheric climatology and atmospheric environmental science research is playing an increasingly important role.

In order to reduce the influence of the blind area on the radar measurement distance, most of them now use coaxial transmitting and receiving devices and concentric transmitting and receiving devices. The telescopic system is an important part of the receiving device, and the index of the receiving optical system is mainly formulated based on the index of the telescopic system. The receiving optical system of the current lidar system mostly adopts the Cassegrain telescope system, in which the focal plane of the telescope can be placed in front of and behind the main mirror of the telescope according to different radar requirements. This patent proposes a method, that is, the position of the primary mirror can be adjusted to achieve the focus position, which can be adjusted according to the requirements, while realizing the versatility of the instrument, it can also realize the parallelism of the primary and secondary mirrors by adjusting the direction of the primary mirror, that is, the focus position can be adjusted according to requirements. to the center of the aperture stop. In addition, for the current high-precision instrument fine particle laser radar for monitoring atmospheric parameters, the measurement accuracy and measurement height are very important. The size of the field of view in the receiving optical system directly affects the measurement distance of the instrument. If the divergence in the transmitting optical system in the laser radar system is too small, it will affect the saturation of the near-field signal and the representativeness of the measured value. If the divergence angle is too large, it will directly measure the height of the instrument. If the laser radar’s emission optical divergence angle is larger than its own receiving optical system, the signal outside the field of view will not be accepted by the receiving optical system at all, resulting in the limitation of measurement parameters. The adjustable position of the focal plane proposed in this patent can directly change the viewing angle of the receiving optical system, avoid the loss of echo signals and enhance the representativeness of measurement values.

For high-precision measuring instruments, the accuracy of self-calibration directly affects the authenticity and accuracy of measurement parameters. At present, artificial calibration methods and CCD images are mostly used for calibration. Two-dimensional calibration itself has many human errors and uncontrollable error factors, so the adjustment accuracy is low, and the degree of automation is poor. However, the currently used CCD calibration method replaces manual calibration and reduces human error, but the calibration accuracy due to the lack of calibration points is not very high. In this patent, the replacement of the aperture diaphragm and the imaging CCD are used for calibration, which not only saves costs but also is simple and clear. At the same time, the target can be imaged in the CCD as a calibration point for calibration. We only need to calibrate the target image, so that It not only improves the accuracy of self-calibration but also reduces the error caused by human debugging.

Contents of the invention

The purpose of the present invention is to provide a high-precision fine-particle laser radar calibration method, which replaces manual calibration and non-target images as reference points, improves accuracy and eliminates human errors caused by manual operations. This invention also proposes a structural form in which the position of the primary mirror in the receiving optical system can be adjusted to realize the adjustable focal plane and focus position, and uses the above-mentioned calibration method to realize the debugging of a whole set of fine-particle laser radar system from coarse adjustment to fine adjustment process.

The technical scheme adopted in the present invention is: a fine-particle lidar system with adjustable focus position, including a laser, an imaging CCD, a control computer, a beam expander, a first right-angle reflective prism, a corner reflector, a plane reflector, and a collimating mirror and the second right-angle reflective prism; wherein the receiving optical system includes a receiving system secondary mirror, a receiving system main body, a primary mirror, an adjusting jack screw, an adjustable aperture diaphragm, a tension spring and a primary mirror holder; the primary mirror is fixed on the primary On the mirror fixing seat, the adjustment of the main mirror depends on the front and rear rotation of the adjusting top screw to adjust the front and rear position of the main mirror and the adjustment of a certain angle, so that the focal plane position and the focus position can be adjusted at the same time; the tension springs at 6 places are fixed On the receiving optical main body and the main mirror fixing seat, ensure that the adjusting top screw can be adjusted normally; the adjustable aperture diaphragm is connected with the receiving system main body with a fine thread, and the adjustable aperture is rotated forward and backward according to the requirements of the receiving optical system The aperture nut is used to find the position of the focal plane, so as to match the appropriate field of view of the fine-particle lidar; the laser light emitted by the laser passes through the beam expander, the first right-angle reflector, the plane reflector, the corner reflector, the receiving optical system, The collimating mirror and the second right-angle reflecting prism reach the imaging CCD, and the imaging CCD is connected to the control computer, which controls the laser.

The present invention also provides a self-calibration method for the fine-particle laser radar system with adjustable focus position. Using the above-mentioned fine-particle laser radar system with adjustable focus position, the laser is turned on, and the laser beam emitted by the laser is expanded by the beam expander and then passed through the first The right-angle reflective prism is reflected to the top of the receiving optical system, and a plane mirror is placed above the receiving optical system. The plane mirror reflects and then passes through the corner reflector. into the receiving optical system. The outgoing light of the receiving optical system passes through the collimating mirror and is reflected by the second right-angle reflective prism into the imaging CCD. The imaging CCD is connected to the main control computer, and the main control computer can control the laser; specifically, an adjustable two-dimensional precision turntable is installed in front of the imaging CCD The second right-angle reflective prism, adjust the adjustment knob below the second right-angle reflective prism at this time, so that the completed target image can be found in the received imaging CCD; write down the target scale value a of the calibrated size, which is formed in the imaging CCD at this moment The image should be blurred, so it is necessary to adjust the calibrated target position forward and backward, and observe the clarity of the target image in the CCD at the same time, find the clearest imaging point and record the target scale value b of the calibrated size at this time, then the front and rear The difference is the value of the front and back offset of the focal plane of the pinhole diaphragm;

Adjust the second right-angle reflective prism so that the center of the imaging image of the target coincides with the very center of the CCD itself, and read the values in the X-axis and Y-axis directions of the two-dimensional turntable. The two values recorded at this time are the focus position distance The distance from the center location.

Compared with the prior art, the present invention has the advantages of:

(1) Compared with the current fine-particle laser radar system, the field of view is mostly fixed or the size of the aperture diaphragm is changed to change the size of the field of view. The position of the primary mirror for debugging in the present invention can not only be automatically adjusted according to requirements The size of the field of view can be further adjusted automatically to improve the accuracy and reliability of the instrument test data.

(2) By replacing the target with a scale to provide a reference image with an adjustable focus position, the cross reticle center of the target itself can more accurately read the value on the turntable, so that the focus position and focal plane position can be precisely adjusted At the same time, the purpose of measurable focus position is realized.

Description of drawings

Fig. 1 is the adjustable mode of the focus position in the receiving optical system in the Cassegrain telescope of the present invention, wherein, 1 is the secondary mirror of the receiving system, 2 is the main body of the receiving system, 3 is the main mirror, 4 is the adjusting top wire, and 5 is adjustable Aperture diaphragm, 6 is a tension spring, and 7 is a fixing seat for the main mirror;

Figure 2 is a target style diagram;

Fig. 3 is the optical path diagram of the coaxial reflective radar transceiver system, wherein, 2 is the main body of the receiving system, 5 is the adjustable aperture diaphragm, 8 is the beam expander, 9 is the first right-angle reflective prism, and 10 is the corner reflector, 11 is a plane reflector, 12 is a collimator, and 13 is a second right-angle reflector.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

The schematic diagram of the structure and principle of the fine-particle lidar receiving optical system with adjustable focus position is shown in Figure 1. The receiving optical system includes the receiving system secondary mirror 1, the receiving system main body 2, the primary mirror 3, the adjusting top wire 4, and the adjustable aperture diaphragm 5, tension spring 6, main mirror holder 7 are formed. The main mirror 3 of the receiving optical system is fixed on the main mirror fixing seat 7 of the receiving optical system, and the adjustment of the main mirror 3 depends on the front and rear rotation of the adjusting screw 4 to adjust the front and rear positions and certain angles of the main mirror 3 of the receiving optical system The adjustment of the focal plane position and the focus position can be adjusted at the same time. The tension spring 6 at position 6 is fixed on the receiving system main body 2 and the main mirror fixing seat 7 to ensure that the adjusting top wire 4 can be in a normal adjustment state. The adjustable pinhole diaphragm 5 is connected with the main body 2 of the receiving system with a fine thread, and the position of the focal plane can be found by rotating the nut of the adjustable pinhole diaphragm 5 back and forth according to the requirements of the receiving optical system, so as to match a suitable fine particle laser radar field of view.

The schematic diagram of the structure principle of the high-precision laser radar automatic calibration system is shown in Figure 3. The fine particle laser radar system mainly includes a computer, a transmitting optical system, a debugging right-angle reflective prism assembly, a receiving optical system, and a CCD for receiving signal sources. Specifically, the high-precision laser radar automatic calibration system includes: a laser, an imaging CCD, a control computer, a receiving optical system, a beam expander 8, a first right-angle reflector 9, a corner reflector 10, a plane reflector 11, a quasi- The straight mirror 12, the second right-angle reflecting prism 13, and the adjustable aperture diaphragm 5 in the receiving optical system are replaced with targets with a calibrated size, and the target pattern is shown in FIG. 2 .

Self-calibration steps:

Turn on the laser, the laser light emitted by the laser is expanded by the beam expander 8 and then reflected to the top of the receiving optical system by the first right-angle reflective prism 9, and a plane mirror 11 is placed above the receiving optical system, after the reflection of the plane mirror 11 After being reflected by the corner reflector 10, the two-dimensional turntable under the corner reflector 10 is adjusted so that the reflected light spot can enter the receiving optical system. The outgoing light of the receiving optical system passes through the collimator 12 and is reflected by the second right-angle reflective prism 13 into the imaging CCD. The imaging CCD is connected to the main control computer, which can control the laser. Specifically, the second right-angle reflective prism 13 of the adjustable two-dimensional precision turntable is installed in front of the imaging CCD. At this time, the adjustment knob below the second right-angle reflective prism 13 is adjusted so that the completed target image can be found in the received imaging CCD. Write down the target scale value a of the calibrated size. At this moment, the image formed in the imaging CCD should be blurred. In this case, it is necessary to adjust the calibrated target position back and forth, and at the same time observe the clarity of the target image in the CCD to find the clearest image. Point and write down the target scale value b of the calibrated size at this time, then the difference before and after is the value of the front and rear offset of the focal plane of the aperture diaphragm.

Adjust the second right-angle reflective prism 13 so that the center of the imaging image of the target coincides with the very center of the CCD itself, read the values in the X-axis and Y-axis directions of the two-dimensional turntable, and the two values recorded at this time are the focus positions The distance from the center location.

Parts not described in detail in the present invention belong to the known techniques of those skilled in the art.

Claims (2)

1. the adjustable fine particle laser radar system in focal position, it is characterized in that: comprise laser instrument, imaging CCD, computer for controlling, beam expanding lens (8), the first right-angle reflecting prism (9), corner reflector (10), plane mirror (11), collimating mirror (12) and the second right-angle reflecting prism (13); Wherein receiving optics comprises receiving system secondary mirror (1), receiving system main body (2), primary mirror (3), regulates jackscrew (4), adjustable aperture (5), tension extension spring (6) and primary mirror holder (7); Primary mirror (3) is fixed on primary mirror holder (7), the adjustment of primary mirror (3) regulates the front and back position of primary mirror (3) and the adjustment of certain angle by regulating the front and back spinning in and out of jackscrew (4), realizes focal plane position and focal position is simultaneously adjustable; The tension extension spring (6) at 6 places is fixed on above receiving system main body (2) and primary mirror holder (7), ensures to regulate jackscrew (4) can adjustment state normally; Adjustable aperture (5) adopts fine thread to be connected with receiving system main body (2), require to rotate by front and back the position that adjustable aperture (5) nut finds focal plane according to receiving optics, thus match suitable fine particle laser radar visual field; The laser that laser instrument sends arrives imaging CCD successively after beam expanding lens (8), the first right-angle reflecting prism (9), plane mirror (11), corner reflector (10), receiving optics, collimating mirror (12), the second right-angle reflecting prism (13), imaging CCD connection control computing machine, computer for controlling controls laser instrument.

2. the self-calibrating method of the adjustable fine particle laser radar system in focal position, utilize the adjustable fine particle laser radar system in the focal position described in claim 1, it is characterized in that: open laser instrument, the laser that laser instrument sends reflexes to the top of receiving optics again after beam expanding lens (8) expands through the first right-angle reflecting prism (9), and above receiving optics holding plane catoptron (11), reflect through 45° angle reverberator (10) again after plane mirror (11) reflection, regulate the dimensional turntable of corner reflector (10) below, the hot spot of reflection is enable to enter in receiving optics, receiving optics emergent light reflexes in imaging CCD through collimating mirror (12) by the second right-angle reflecting prism (13), imaging CCD is connected with main control computer, main control computer can control laser instrument, concrete, second right-angle reflecting prism (13) of adjustable two dimension precise rotating platform is installed in imaging CCD front, now regulate the conciliation knob of the second right-angle reflecting prism (13) below, make the target image that can find in the imaging CCD of reception, write down the target scale value a demarcating size, this is engraved in imaging in imaging CCD should be fuzzy, at this moment the target position that before and after just needing, adjustment is demarcated, observe the sharpness of target image in CCD simultaneously, find the most clearly imaging point and write down the target scale value b of demarcation size now, then the difference before and after is exactly the numerical value offset before and after aperture focal plane,

The second right-angle reflecting prism (13) is regulated to make the image center of target at CCD and the very center superposition of CCD itself, read the X-axis of dimensional turntable and the numerical value of Y direction, two numerical value now write down are the distance of distance center position, focal position.