Dispersion and beam wander combined atmospheric refraction error measurement device

Abstract

A device for measuring atmospheric refraction error combining dispersion and beam drift methods is disclosed, belonging to the field of atmospheric refraction error measurement technology. It solves the technical problems in existing optical measurement methods for atmospheric refraction error, where turbulence parameter measurements neglect secondary influencing factors, while dispersion methods require high precision in dispersion angle measurement. The measuring device of this invention includes a dual-wavelength laser, a collimating lens, a power attenuator, a focusing lens, and a high-resolution dual-color CCD arranged sequentially along the light propagation direction. The dual-wavelength laser outputs dual-wavelength laser light, which is collimated by the collimating lens and then incident on the power attenuator to achieve the same optical power. The laser light then passes through a turbulent region and is focused onto the high-resolution dual-color CCD by the focusing lens. Atmospheric refraction error is calculated using both beam drift and dispersion methods, thus achieving atmospheric refraction error measurement. This measuring device has a simple structure and can obtain high-precision results with relatively low-precision measurements.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of atmospheric refraction error measurement, and particularly relates to a dispersion and beam drift combined atmospheric refraction error measurement device. BACKGROUND

[0002] The refractive index distribution is related to atmospheric parameters such as temperature, pressure and humidity, and different refractive indexes in space cause the light to not propagate along a straight line in the atmosphere, which has a serious impact on the optical measurement precision of the light path exposed to the atmosphere, especially in long-distance high-precision application scenarios. With the increasing complexity of thermal radiation, convection and building environment in near-surface measurement, the influence of irregular atmosphere on measurement is also increasingly serious, so it is necessary to accurately measure the atmospheric refraction error and compensate it to improve the related measurement precision. Traditional non-optical atmospheric refraction measurement is mainly based on the ray tracing method of the layered model, this method has a large calculation scale and needs to obtain the atmospheric parameter distribution in space by other means, and the accuracy of measurement can be improved by optimizing the atmospheric layered model. The optical method to obtain the atmospheric refraction error does not need to obtain the large parameters in space, and can effectively realize the real-time compensation of the influence of atmospheric refraction on measurement. Traditional optical methods include turbulence parameter measurement and dispersion, and the turbulence parameter measurement includes light intensity flicker method and beam drift method. The turbulence parameter measurement method is based on the phenomenon that the light propagates in the atmosphere is affected by turbulence, and the refractive index structure constant representing turbulence is obtained by measuring the flicker, dispersion and offset of the received light spot and l0, and the average refractive index gradient is determined by using the two parameters to obtain the turbulence heat flux H to compensate the atmospheric refraction error, but the turbulence parameter measurement mainly considers the relationship between the turbulence heat flux and the average refractive index gradient, and ignores other secondary factors. The dispersion method is based on the principle that different wavelengths have different refractive indexes in the medium, and the atmospheric refraction error is obtained by the correlation between the dispersion angle and the measurement wavelength, but the dispersion method has high measurement precision requirements for the dispersion angle, for example, in the double-wavelength dispersion measurement of 430nm and 860nm, the measurement precision of the dispersion angle needs to be about 42 times of the atmospheric refraction error measurement. SUMMARY

[0003] Therefore, the application provides a dispersion and beam drift combined atmospheric refraction error measurement device to solve the technical problems that the turbulence parameter measurement mainly considers the relationship between the turbulence heat flux and the average refractive index gradient, and ignores other secondary factors, and the dispersion method has high measurement precision requirements for the dispersion angle.

[0004] The application achieves the above-mentioned purposes by adopting the following technical solutions.

[0005] The atmospheric refraction error measuring device with dispersion combined with beam drift of the present application comprises a double-wavelength laser, a collimating lens, a power attenuation sheet, a focusing lens and a high-resolution dual-color CCD arranged in sequence along the propagation direction of light, and a turbulent region is located between the power attenuation sheet and the focusing lens.

[0006] The double-wavelength laser outputs double-wavelength laser, the collimating lens collimates the double-wavelength laser output by the double-wavelength laser, the collimated double-wavelength laser is incident to the power attenuation sheet, the power attenuation sheet processes the double-wavelength laser to have the same optical power, the double-wavelength laser emitted from the power attenuation sheet is incident to the turbulent region, the focusing lens receives the double-wavelength laser passing through the turbulent region and focuses the double-wavelength laser on the high-resolution dual-color CCD, the double-wavelength laser spots on the high-resolution dual-color CCD are processed, the atmospheric refraction error is obtained by using the beam drift method to process any one of the two-wavelength spots, the atmospheric refraction error is obtained again by using the dispersion method to process the two-wavelength spots, the atmospheric refraction error obtained by the beam drift method is taken as a compensation term of the atmospheric refraction error obtained by the dispersion method, so that the atmospheric refraction error measurement is realized.

[0007] Further, the distance between the collimating lens and the double-wavelength laser is exactly the focal length of the collimating lens.

[0008] Further, the high-resolution dual-color CCD is located at the focal plane of the focusing lens.

[0009] Further, the parameters of the power attenuation sheet are determined by the following method:

[0010] The double-wavelength laser, the collimating lens, the power attenuation sheet, the focusing lens, the high-resolution dual-color CCD and the turbulent region are arranged in sequence along the propagation direction of light.

[0011] The double-wavelength laser outputs double-wavelength laser, the collimating lens collimates the double-wavelength laser output by the double-wavelength laser, the collimated double-wavelength laser is incident to the power attenuation sheet, the power attenuation sheet processes the double-wavelength laser and then the double-wavelength laser is incident to the focusing lens, the focusing lens focuses the double-wavelength laser on the high-resolution dual-color CCD, the power attenuation sheet is adjusted by the light intensity of the two-wavelength laser focusing spots received by the high-resolution dual-color CCD, so that the two-wavelength lasers have the same optical power.

[0012] Further, the chromatic aberration of the collimating lens and the focusing lens causes the centroid separation distance of the two-wavelength receiving spots on the high-resolution dual-color CCD to not exceed one pixel.

[0013] Further, the process of processing the double-wavelength laser spots on the high-resolution dual-color CCD is as follows:

[0014] On the one hand, the refractive index structure constant characterizing turbulence is calculated by selecting a laser beam of a specific wavelength. The turbulent thermal flux H is obtained through these two parameters, along with the minimum turbulence scale l0, thereby calculating the average refractive index gradient in the turbulent region and obtaining the atmospheric refraction error.

[0015] On the other hand, the light spots of the two wavelength lasers are separated, and the resolution is improved by pixel interpolation technology to obtain the interpolated light spots. The interpolated light spots are then image-processed to find the centroids of the corresponding light spots and obtain the dispersion angle. Finally, the atmospheric refraction error under different measurement wavelengths is obtained by using the correlation coefficient between wavelength and dispersion angle.

[0016] The principle of this invention is as follows: Two wavelength laser beams emitted by a dual-wavelength laser form two measurement optical paths, achieving a completely shared optical path and thus avoiding the influence of component errors or assembly errors on measurement accuracy. A power attenuator ensures equal measurement power for both optical paths, avoiding the effects of power inconsistency. The receiving device uses a high-resolution dual-color CCD to receive both optical paths, achieving complete path sharing for the entire atmospheric refraction error measurement and effectively combining the two measurement schemes. During data processing, pixel interpolation can improve the measurement accuracy of the dispersion angle, and the beam drift method result can be used as a compensation term for the dispersion method according to actual conditions, achieving high-precision measurement of atmospheric refraction error.

[0017] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0018] The atmospheric refraction error measurement device combining dispersion and beam drift of the present invention combines the beam drift method and the dispersion method in turbulence parameter measurement, realizing the joint measurement of the two schemes on the same device. By using the result obtained by the beam drift measurement method as the correction term of the dispersion result (to verify whether the measured atmospheric refraction error is accurate), it can solve the problem that the dispersion method requires high dispersion angle measurement accuracy. Thus, under the premise of low dispersion angle measurement accuracy, it can provide a high-precision atmospheric refraction error considering factors other than temperature, and achieve effective compensation for atmospheric refraction in near-ground measurements.

[0019] The atmospheric refraction error measurement device combining dispersion and beam drift of the present invention uses a high-resolution dual-wavelength CCD that does not need to satisfy the relationship between the dispersion angle measurement and the actual angle measurement. It can achieve high-precision measurement of atmospheric refraction error under the premise of the same measurement accuracy or with small difference.

[0020] The atmospheric refraction error measurement device combining dispersion and beam drift of the present invention has a simple structure compared with other measurement methods such as light intensity scintillation method, and can obtain high-precision results with relatively low-precision measurement. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 This is a schematic diagram of the structure of the high-precision atmospheric refraction error measurement that combines dispersion measurement and turbulence parameter measurement according to the present invention.

[0023] Figure 2 A schematic diagram of the device used to adjust the power attenuator during the design process of the atmospheric refraction error measurement device combining dispersion and beam drift of the present invention.

[0024] Figure 3 A flowchart illustrating the high-resolution dual-color CCD processing of the spot of a dual-wavelength laser using an atmospheric refraction error measurement device combining dispersion and beam drift according to the present invention.

[0025] In the figure, 1 is a dual-wavelength laser source, 2 is a collimating lens, 3 is a power attenuator, 4 is a focusing lens, 5 is a high-resolution dual-color CCD, and 6 is a turbulent region. Detailed Implementation

[0026] To further understand the present invention, preferred embodiments of the present invention are described below. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.

[0027] like Figure 1 As shown, the atmospheric refraction error measurement device combining dispersion and beam drift of the present invention includes a dual-wavelength laser 1, a collimating lens 2, a power attenuator 3, a focusing lens 4 and a high-resolution dual-color CCD 5 arranged sequentially along the direction of light propagation, and the turbulent region 6 is located between the power attenuator 3 and the focusing lens 4.

[0028] The transmitting device consists of a dual-wavelength laser 1, a collimating lens 2, and a power attenuator 3. The receiving device consists of a focusing lens 4 and a high-resolution dual-color CCD 5. The dual-wavelength laser 1 outputs a dual-wavelength laser. The collimating lens 2 collimates the dual-wavelength laser output from the dual-wavelength laser 1. The collimated dual-wavelength laser propagates to the power attenuator 3, which processes the two wavelengths to achieve the same optical power. The dual-wavelength laser emitted from the power attenuator 3 is then incident on the turbulent region 6. The focusing lens 4 receives the dual-wavelength laser after it has passed through the turbulent region 6 and focuses it onto the high-resolution dual-color CCD 5. The dual-wavelength laser spot on the high-resolution dual-color CCD 5 is processed to measure the atmospheric refraction error after the dual-wavelength laser passes through the turbulent region 6. Specifically, the atmospheric refraction error is obtained by processing either of the two wavelength spots using the beam drift method, and the atmospheric refraction error is obtained again by processing the two wavelength spots using the dispersion method. The atmospheric refraction error obtained by the beam drift method is used as a compensation term for the atmospheric refraction error obtained by the dispersion method, thus achieving the measurement of atmospheric refraction error.

[0029] In the above technical solution, the distance between the collimating lens 2 and the dual-wavelength laser 1 is exactly the focal length of the collimating lens 2. The power attenuator 3 is placed at any position between the turbulent region 6 and the collimating lens 2. The high-resolution dual-color CCD 5 is located at the focal plane of the focusing lens 4. The dual-wavelength laser 1, collimating lens 2, power attenuator 3, focusing lens 4, and high-resolution dual-color CCD 5 are usually arranged sequentially from left to right, but are not limited to this arrangement.

[0030] In the above technical solution, the collimating lens 2 and the focusing lens 4 need to be achromatic, requiring that the centroid separation distance of the two wavelength receiving light spots generated by the chromatic difference of the collimating lens 2 and the focusing lens 4 on the high-resolution dual-color CCD 5 cannot exceed one pixel.

[0031] In the above technical solution, the output power of the two wavelength lasers may be inconsistent, and the coatings of related optical components have different transmittance for different wavelengths, resulting in different incident powers for the two wavelength lasers, which has a significant impact on the measurement. The power attenuator 3 processes the dual-wavelength lasers to have the same optical power, thereby eliminating the impact of different laser powers on the accuracy of the dispersion angle measurement. For example... Figure 2As shown, the parameters of the power attenuator 3 are determined by the following method: a dual-wavelength laser 1, a collimating lens 2, a power attenuator 3, a focusing lens 4, a high-resolution dual-color CCD 5, and a turbulence region 6 are arranged sequentially along the direction of light propagation; the dual-wavelength laser 1 outputs dual-wavelength laser, the collimating lens 2 collimates the dual-wavelength laser output by the dual-wavelength laser 1, the collimated dual-wavelength laser is incident on the power attenuator 3, the power attenuator 3 processes the dual-wavelength laser and then incident on the focusing lens 4, the focusing lens 4 focuses the dual-wavelength laser onto the high-resolution dual-color CCD 5, and the power attenuator 3 is adjusted by the light intensity of the focused spot of the two wavelength lasers received by the high-resolution dual-color CCD 5, so that the two wavelength lasers have the same optical power.

[0032] In the above technical solutions, such as Figure 3 As shown, the process of processing the dual-wavelength laser spot on a high-resolution dual-color CCD5 is as follows: On the one hand, one wavelength laser is selected to calculate the refractive index structure constant characterizing turbulence. Using the minimum turbulence scale l0 and these two parameters, the turbulent thermal flux H is obtained, and the average refractive index gradient at location 6 in the turbulent region is calculated, thus yielding the atmospheric refraction error. On the other hand, the laser spots of the two wavelengths are separated, and pixel interpolation technology can be used to improve resolution. Image processing is then performed on the interpolated spots to find the centroids of the corresponding spots, thus obtaining the dispersion angle. Based on the obtained dispersion angle, the atmospheric refraction error at different measurement wavelengths is obtained through the correlation coefficient between wavelength and dispersion angle. The centroids of the two wavelength receiving spots can be obtained using adaptive thresholding and other centroid algorithms. After obtaining the atmospheric refraction errors calculated by the two schemes, the atmospheric refraction error measured by the dispersion method can be used as the main term, and the result of the beam drift method can be used as a compensation term, thereby achieving a higher accuracy in atmospheric refraction error measurement. Specifically, if the atmospheric refraction error measured by the dispersion method is θ1, and the atmospheric error measured by the beam drift method is θ2, the total atmospheric refraction error can be expressed as θ = θ1 + aθ2, where a is related to the dual-wavelength method and the interpolation algorithm in the dispersion method. In practice, the actual value of 'a' can be obtained by measuring the atmospheric refraction error of a known target. That is, by using a azimuth measuring instrument to measure the known target and obtain the actual atmospheric refraction error θ, and after obtaining the values ​​of two atmospheric refraction errors θ1 and θ2 using the instrument, the value of 'a' can be obtained by solving the above formula, and thus applied to random targets with unknown azimuth.

[0033] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the embodiments. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all embodiments here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An atmospheric refraction error measurement device combining dispersion and beam drift, characterized in that, It includes a dual-wavelength laser (1), a collimating lens (2), a power attenuator (3), a focusing lens (4), and a high-resolution dual-color CCD (5) arranged sequentially along the direction of light propagation, and the turbulent region (6) is located between the power attenuator (3) and the focusing lens (4); The dual-wavelength laser (1) outputs dual-wavelength lasers. The collimating lens (2) collimates the dual-wavelength lasers output by the dual-wavelength laser (1). The collimated dual-wavelength lasers are incident on the power attenuator (3). The power attenuator (3) processes the dual-wavelength lasers to have the same optical power. The dual-wavelength lasers emitted from the power attenuator (3) are incident on the turbulent region (6). The focusing lens (4) receives the dual-wavelength lasers that have passed through the turbulent region (6) and focuses the dual-wavelength lasers onto the high-resolution dual-color CCD (5). The dual-wavelength laser spots on the high-resolution dual-color CCD (5) are processed. The atmospheric refraction error is obtained by processing either of the two wavelength spots using the beam drift method. At the same time, the atmospheric refraction error is obtained again by processing the two wavelength spots using the dispersion method. The atmospheric refraction error obtained by the beam drift method is used as a compensation term for the atmospheric refraction error obtained by the dispersion method, thereby realizing the measurement of atmospheric refraction error.

2. The atmospheric refraction error measuring device combining dispersion and beam drift according to claim 1, characterized in that, The distance between the collimating lens (2) and the dual-wavelength laser (1) is exactly the focal length of the collimating lens (2).

3. The atmospheric refraction error measuring device combining dispersion and beam drift according to claim 1, characterized in that, The high-resolution dual-color CCD (5) is located at the focal plane of the focusing lens (4).

4. The atmospheric refraction error measuring device combining dispersion and beam drift according to claim 1, characterized in that, The parameters of the power attenuator (3) are determined by the following method: Along the direction of light propagation, a dual-wavelength laser (1), a collimating lens (2), a power attenuator (3), a focusing lens (4), a high-resolution dual-color CCD (5), and a turbulent region (6) are arranged sequentially. A dual-wavelength laser (1) outputs dual-wavelength lasers. A collimating lens (2) collimates the dual-wavelength lasers output by the dual-wavelength laser (1). The collimated dual-wavelength lasers are incident on a power attenuator (3). The power attenuator (3) processes the dual-wavelength lasers and then incident them onto a focusing lens (4). The focusing lens (4) focuses the dual-wavelength lasers onto a high-resolution dual-color CCD (5). The power attenuator (3) is adjusted by the light intensity of the focused spot of the two wavelength lasers received by the high-resolution dual-color CCD (5) to achieve the same optical power for the two wavelength lasers.

5. The atmospheric refraction error measuring device combining dispersion and beam drift according to claim 1, characterized in that, The centroid separation distance between the two wavelength receiving spots generated by the chromatic difference of the collimating lens (2) and the focusing lens (4) on the high-resolution dual-color CCD (5) cannot exceed one pixel.

6. The atmospheric refraction error measuring device combining dispersion and beam drift according to claim 1, characterized in that, The process of processing the dual-wavelength laser spot on the high-resolution dual-color CCD (5) is as follows: On the one hand, the refractive index structure constant characterizing turbulence is calculated by selecting a laser beam of a specific wavelength. With the minimum turbulence scale l0, the turbulence thermal flux H is obtained through these two parameters, and the average refractive index gradient at the turbulence region (6) is calculated, thereby obtaining the atmospheric refractive error; On the other hand, the light spots of the two wavelength lasers are separated, and the resolution is improved by pixel interpolation technology to obtain the interpolated light spots. The interpolated light spots are then image-processed to find the centroids of the corresponding light spots and obtain the dispersion angle. Finally, the atmospheric refraction error under different measurement wavelengths is obtained by using the correlation coefficient between wavelength and dispersion angle.

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