阅读说明：本技术 高动态范围恒星探测成像方法及星敏感器 (High dynamic range fixed star detection imaging method and star sensor ) 是由 何家维 何昕 魏仲慧 吕游 穆治亚 张磊 王军 于 2019-10-31 设计创作，主要内容包括：本发明公开一种高动态范围恒星探测成像方法及星敏感器,其中的探测成像方法包括：S1、用分光棱镜将光学镜头收集的星光能量按能量比例分配为至少两条不同响应度的光路；S2、至少两条不同响应度的光路分别通过一路图像传感器同步进行光电转换,形成不同响应度的低动态范围图像；S3、通过图像处理与控制电路提取出各幅低动态范围图像内不同亮度等级的恒星的有效灰度信息,合成高动态范围的数字星图。利用本发明能够实现星敏感器的高灵敏度、高分辨率、高动态范围的恒星探测。(The invention discloses a detection imaging method for a fixed star with a high dynamic range and a star sensor, wherein the detection imaging method comprises the following steps: s1, distributing the star light energy collected by the optical lens into at least two light paths with different responsivities according to the energy proportion by using a light splitting prism; s2, synchronously performing photoelectric conversion on at least two light paths with different responsivities through one image sensor respectively to form low dynamic range images with different responsivities; and S3, extracting effective gray scale information of stars with different brightness levels in each low dynamic range image through an image processing and control circuit, and synthesizing a digital star map with a high dynamic range. The star sensor can realize the star detection with high sensitivity, high resolution and high dynamic range.)

1. A high dynamic range sidereal detection imaging method is characterized by comprising the following steps:

s1, distributing the star light energy collected by the optical lens into at least two light paths with different responsivities according to the energy proportion by using a light splitting prism;

s2, the at least two light paths with different responsivities are respectively subjected to photoelectric conversion synchronously through one image sensor to form low dynamic range images with different responsivities;

and S3, extracting effective gray scale information of stars with different brightness levels in each low dynamic range image through an image processing and control circuit, and synthesizing a digital star map with a high dynamic range.

2. The method according to claim 1, wherein the image sensors are aligned in time with integration time points to obtain images with different responsivities by simultaneous exposure.

3. The method according to claim 2, wherein the energy ratio of each optical path is changed by coating a film on the beam splitter prism, and the energy ratio of the optical path received by each image sensor is controlled to obtain a plurality of low dynamic range images with different responsivity ranges.

4. The method according to claim 2, wherein a plurality of low dynamic range images with different responsivity ranges are obtained by different exposure parameters of each image sensor.

5. The method according to claim 2, wherein a plurality of low dynamic range images of different responsivity ranges are obtained using a plurality of image sensors of the same series having the same resolution as the pixel size and different sensitivities.

6. The high-dynamic-range sidereal detection imaging method according to claim 1, wherein the image processing and control circuit performs star recognition and attitude calculation on the digital star map after synthesizing the digital star map, and finally performs communication framing to form attitude data for outputting.

7. The star sensor for star detection is characterized by comprising an optical lens, a beam splitter prism and an electronic system; wherein the content of the first and second substances,

the optical lens is used for collecting the star light energy of a certain day area;

the beam splitter prism is used for distributing the star light energy collected by the optical lens into at least two light paths with different responsivities according to an energy proportion;

the electronic system comprises image sensors and an image processing and control circuit, the number of the image sensors is the same as that of light paths split by the beam splitter prism, and each image sensor is used for synchronously carrying out photoelectric conversion on the corresponding light path to form low dynamic range images with different responsivities; the image processing and control circuit is used for carrying out data fusion on the low dynamic range images with different responsivities to extract effective gray information of stars with different brightness levels in each low dynamic range image and synthesize a digital star map with a high dynamic range.

8. The star sensor for star detection according to claim 7, wherein the image sensor is a scientific grade CMOS sensor.

9. The star sensor for star detection according to claim 8, wherein said electronics system further comprises an interface circuit for outputting attitude data formed by said image processing and control circuit performing planetary recognition, attitude calculation and communication framing on said digital star map.

10. The star sensor for star detection according to claim 7, wherein the image processing and control circuit is an architecture of FPGA with DDR.

Technical Field

The invention relates to the technical field of attitude measurement sensitive equipment and star sensors, in particular to a high-dynamic-range star detection imaging method and a star sensor.

Background

The measurement principle of the star sensor is that the component of a star vector in a star sensor coordinate system is measured by imaging a star space, and then the three-axis attitude of a carrier relative to an inertial coordinate system is determined by utilizing the precise position of a known star. The star sensor takes a detected star as a measurement basis, performs star detection through an optical system and an image sensor to ensure that enough usable star number exists in a field of view, and performs information processing such as target extraction, star recognition, attitude calculation and the like. When the detection limit star of the star sensor is not high, the sufficient number of the available stars can be ensured by increasing the view field, and the imaging dynamic range of the image sensor can still meet the requirement of simultaneously detecting the bright star and the dark star. However, in some application fields, the measurement accuracy of the star sensor with a small field of view is higher, at this time, the sensitivity of the star sensor and the detection limit star need to be improved to ensure the number of available stars, the brightness range of the star to be detected at this time exceeds the dynamic range of the image sensor, bright stars and dark stars cannot be considered in the same image, the gray level of the bright stars in the star map is saturated or the dark stars cannot be seen, and the target extraction and star recognition of the star map are not facilitated.

When a bright star and a dark star appear in the same image, the star sensor is required to have High Dynamic Range (HDR) imaging capability. For an image sensor, the dynamic range may be defined as the ratio of the most unsaturated input signal to the least detectable input signal. For a star sensor, dynamic range may be understood as the ratio of the brightest detectable unsaturated star irradiance to the darkest detectable star irradiance. According to the definition, the star and the like are taken as target energy measurement standards, and the imaging dynamic range is required to reach 112dB on the assumption that the star detection range is from-1 and the like to 13 and the like. At present, the highest dynamic range which can be achieved by an image sensor (imaging device) is about 90dB generally in the world, and the imaging with the ultra-large dynamic range is difficult to realize only by the characteristics of the imaging device. The multiple exposure synthesis method commonly used in the HDR imaging field needs to perform multiple exposure on the same scene in a time-sharing manner, the time resolution of the method is reduced, the data updating rate of the star sensor is reduced, the artifact is easily generated on the HDR image, and the method is not suitable for high-dynamic carrier attitude measurement. Although the methods such as the digital micromirror device imaging method, the detector pixel synthesis method and the like can expand the imaging dynamic range, the methods have limitations and are not suitable for being applied to star sensors. Therefore, a brand new star sensor design idea is needed to realize the high dynamic range star detection of the star sensor.

Disclosure of Invention

The invention aims to solve the technical problems and provides a high-dynamic-range star detection imaging method and a star sensor. The invention can acquire the digital star map with high dynamic range on the premise of not reducing the spatial resolution and the time resolution, so that the star sensor can effectively detect the bright star and the dark star in the same star map.

In order to achieve the purpose, the invention adopts the following specific technical scheme:

the invention provides a high dynamic range star detection imaging method, which comprises the following steps:

s1, distributing the star light energy collected by the optical lens into at least two light paths with different responsivities according to the energy proportion by using a light splitting prism;

s2, synchronously performing photoelectric conversion on at least two light paths with different responsivities through one image sensor respectively to form low dynamic range images with different responsivities;

and S3, extracting effective gray scale information of stars with different brightness levels in each low dynamic range image through an image processing and control circuit, and synthesizing a digital star map with a high dynamic range.

Preferably, the image sensors are synchronously exposed with integration time points aligned in time to obtain images of different responsivities.

Preferably, the energy proportion of each light path is changed through the coating of the light splitting prism, the energy proportion of the light path received by each image sensor is controlled, and a plurality of low dynamic range images in different responsivity ranges are obtained.

Preferably, a plurality of low dynamic range images of different responsivity ranges are obtained by different exposure parameters of the respective image sensors.

Preferably, a plurality of low dynamic range images of different responsivity ranges are obtained using a plurality of image sensors of the same series having the same resolution as the pixel size and different sensitivities.

Preferably, after the image processing and control circuit synthesizes the digital star maps, the image processing and control circuit performs star recognition and attitude calculation on the digital star maps, and finally performs communication framing to form attitude data.

The invention also provides a star sensor for star detection, which comprises an optical lens, a beam splitter prism and an electronic system; wherein the content of the first and second substances,

the optical lens is used for collecting the star light energy in a certain day area;

the beam splitter prism is used for distributing the star light energy collected by the optical lens into at least two light paths with different responsivities according to the energy proportion;

the electronic system comprises image sensors and an image processing and control circuit, wherein the number of the image sensors is the same as that of light paths split by the beam splitter prism, and each image sensor is used for synchronously carrying out photoelectric conversion on the corresponding light path to form low dynamic range images with different responsivities; the image processing and control circuit is used for carrying out data fusion on the low dynamic range images with different responsivities to extract effective gray information of stars with different brightness levels in each low dynamic range image and synthesize a digital star map with a high dynamic range.

Preferably, the image sensor is a scientific grade CMOS sensor.

Preferably, the electronic system further comprises an interface circuit for outputting the attitude data formed by the image processing and control circuit for planetary recognition, attitude calculation and communication framing of the digital star map.

Preferably, the image processing and control circuit is an architecture of FPGA collocated with DDR.

The invention can obtain the following technical effects:

1. the star sensor provided by the invention can simultaneously acquire the gray information of bright stars and dark stars, and avoids the problem that the gray information is lost due to the saturation of the bright stars caused by insufficient dynamic range of imaging.

2. Different from a time-sharing multi-exposure mode, the invention adopts a plurality of image sensors to expose the same star field at the same time so as to solve the problem that the time resolution can be reduced, and is suitable for measurement under the condition of carrier motion.

3. The invention does not carry out optical modulation or synthesis at the pixel level, does not reduce the spatial resolution, and can acquire the sidereal image with high sensitivity, high resolution and high dynamic range.

Drawings

FIG. 1 is a schematic diagram of a logical structure of a star sensor for star detection according to one embodiment of the present invention;

FIG. 2 is a schematic diagram of the operating principle of a star sensor for star detection according to an embodiment of the present invention.

FIG. 3 is a flow diagram of a high dynamic range sidereal detection imaging method according to one embodiment of the present invention.

Wherein the reference numerals include: the system comprises a light shield 200, an optical lens 201, a beam splitter prism 202, a low responsivity light path 203, a high responsivity light path 204, an L sensor 205, an H sensor 206, an image processing and control circuit 207 and an interface circuit 208.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not to be construed as limiting the invention.

Referring to fig. 1 and 2, an embodiment of the invention provides a star sensor for star detection, including: an optical lens 201, a beam splitter prism 202 and an electronic system, wherein the optical lens 201 is used for collecting star light energy in a certain day area. The beam splitter prism 202 is used for distributing the star light energy collected by the optical lens 201 into at least two light paths with different responsivities according to the energy proportion. The electronic system comprises image sensors and an image processing and control circuit, wherein the number of the image sensors is the same as that of light paths split by the beam splitter prism, namely one light path corresponds to one image sensor, and each image sensor is used for synchronously carrying out photoelectric conversion on the light path corresponding to the image sensor to form low dynamic range images with different responsivities; the image processing and control circuit 207 is used for performing data fusion on the low dynamic range images with different responsivities to extract effective gray information of stars with different brightness levels in each low dynamic range image, and synthesizing a digital star map with a high dynamic range.

Furthermore, the star sensor capable of realizing the high dynamic range fixed star detection also comprises a mechanical structure, wherein the mechanical structure comprises a shell, and an optical lens base, a beam splitter prism base and a circuit board fixing frame which are respectively arranged in the shell, the optical lens is arranged on the optical lens base, the beam splitter prism is arranged on the beam splitter prism base, and the electronic system is arranged on the circuit board fixing frame.

In a preferred embodiment, a light shield 200 is attached to the front end of the optical lens 201, and the light shield 200 is used to suppress stray light rays of the sun and the moon from entering the optical lens 201.

The following description will take an example in which the beam splitter prism 202 splits two optical paths, and splitting more optical paths can be similarly obtained.

The two optical paths split by the beam splitter prism 202 are a low-responsivity optical path 203 (hereinafter, referred to as an L optical path) and a high-responsivity optical path 204 (hereinafter, referred to as an H optical path), respectively, and the energy distributed by the H optical path 204 is greater than that distributed by the L optical path 203. Corresponding to the L optical path 203 is a low-responsivity image sensor 205 (hereinafter, simply referred to as an L sensor) for photoelectrically converting the L optical path 203 to form an image of low responsivity (hereinafter, simply referred to as an L image). Corresponding to the H optical path 204 is a high-responsivity image sensor 206 (hereinafter, simply referred to as an H sensor) for photoelectrically converting the H optical path 204 to form a high-responsivity image (hereinafter, simply referred to as an H image), both of which are low-dynamic-range images.

The image processing and control circuit 207 is configured to perform data fusion on the L image and the H image by using a data fusion method to extract effective gray information of stars with high brightness levels and low brightness levels in the L image and the H image, and synthesize the effective gray information into a digital star map with a high dynamic range, where the digital star map is a star image. According to the invention, the gray information of the stars with high brightness levels and low brightness levels is obtained simultaneously, so that the problem that the gray information is lost due to the saturation of the stars due to insufficient dynamic range of imaging is avoided.

In a specific embodiment of the present invention, the image processing and control circuit 207 adopts an FPGA (field programmable Gate Array) to implement a Data calculation function in cooperation with a DDR (Double Data Rate) architecture, performs Data fusion on the L image and the H image to extract effective gray information of stars in the L image and the H image, and a specific calculation process of synthesizing the effective gray information into a high dynamic range digital star map is the prior art, and therefore, details are not described herein.

The invention can adjust the energy distribution of the L light path 203 and the H light path 204 by the following three ways:

first mode

The energy proportion of the L light path 203 and the H light path 204 is changed by coating a film on the beam splitter prism 202, so that the energy proportion of the light paths received by the L sensor 205 and the H sensor 206 is controlled, and a plurality of low dynamic range images in different responsivity ranges are obtained.

Second mode

Sensitivity control is realized by the L sensor 205 and the H sensor 206 with different exposure parameters, so that two low dynamic range images with different responsivity ranges are obtained. For example: if the H optical path 204 employs high-gain shooting and the L optical path 203 employs low-gain shooting, two low-dynamic-range images with different responsivities are acquired.

Third mode

The L sensor 205 and the H sensor 206 obtain two low dynamic range images with different responsivity ranges by using two image sensors of the same series having the same resolution as the pixel size and different sensitivities.

It should be noted that the low dynamic range may be limited by the integration time, and the integration time of the image sensor may be shortened by changing the aperture of the optical lens, so as to obtain a suitable low dynamic range, so that each image sensor obtains a suitable low dynamic range image.

In another embodiment of the invention, after parameters such as the ratio of the light splitting energy of the L optical path to the light splitting energy of the H optical path, the integration time and the like are determined, the limit detection stars and the like and the adjacent saturated stars and the like of the L image and the H image can be calculated according to indexes such as quantum efficiency and the like of the image sensor with a specific model, so that the dynamic range of the star sensor can be determined.

After the image processing and control circuit synthesizes the digital star map, the star recognition and attitude calculation are carried out on the digital star map, and finally communication framing is carried out to form attitude data. In some embodiments of the present invention, the electronic system further includes an interface circuit 208, the attitude data is finally output to the outside through the interface circuit 208, and the interface circuit 208 is a prior art, and therefore, the details are not described herein.

The working principle of the invention is as follows: the star detection sensor for the fixed star in the high dynamic range adopts a light splitting prism of a common light path to generate a plurality of light paths of the same scene at the same time, each light path carries out photoelectric conversion through a corresponding image sensor to obtain a plurality of images in the low dynamic range, then the effective gray information of the fixed star with different brightness levels in each image is extracted from the plurality of images in the low dynamic range by using a data fusion method, and the effective gray information is synthesized into a digital star map to obtain a star image. Because the invention does not carry on the optical modulation or synthesis of the picture element level, the spatial resolution does not reduce, can obtain the sidereal image of high sensitivity, high resolution, high dynamic range.

The above details describe the star sensor structure for star detection provided by the embodiments of the present invention, and the present invention further provides a detection imaging method for a high dynamic range of a star by using a star sensor, corresponding to the star sensor.

The embodiment of the invention provides a high dynamic range star detection imaging method, which comprises the following steps:

step 1, distributing the star light energy collected by the optical lens into at least two light paths with different responsivities according to an energy proportion by using a light splitting prism.

The reason for distributing the capacities of the multiple light paths according to different energy proportions is to obtain images with different responsivities after photoelectric conversion is carried out by the image sensor so as to extract effective gray information of stars with high brightness levels and low brightness levels in each responsivity image.

And 2, synchronously performing photoelectric conversion on at least two light paths with different responsivities through one image sensor respectively to form low dynamic range images with different responsivities.

By adjusting the energy distribution ratio of each optical path, low dynamic range images of different responsivity ranges can be obtained.

The embodiment of the invention can adjust the energy distribution of each light path in the following three ways:

first mode

The energy proportion of each light path is changed by coating a film on the light splitting prism, so that the energy proportion of the light path received by each image sensor is controlled, and a plurality of low dynamic range images in different responsivity ranges are obtained.

Second mode

Sensitivity control is realized by different exposure parameters of each image sensor, so that a plurality of low dynamic range images with different responsivity ranges are obtained. For example: if the H optical path adopts high-gain shooting, and the L optical path adopts low-gain shooting, two low-dynamic-range images with different responsivities are obtained.

Third mode

Each path of image sensor adopts a plurality of image sensors of the same series with the same resolution and the same pixel size but different sensitivities to obtain a plurality of low dynamic range images with different responsivity ranges.

It should be noted that the low dynamic range may be limited by the integration time, and the integration time of the image sensor may be shortened by changing the aperture of the optical lens, so as to obtain a suitable low dynamic range, so that each image sensor obtains a suitable low dynamic range image.

And 3, extracting effective gray information of stars with different brightness levels in each low dynamic range image through an image processing and control circuit, and synthesizing a digital star map with a high dynamic range.

After the image processing and control circuit synthesizes the digital star map, the star recognition and attitude calculation are carried out on the digital star map, and finally communication framing is carried out to form attitude data. The attitude data is finally output through an interface circuit.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

The above embodiments of the present invention should not be construed as limiting the scope of the present invention. Any other corresponding changes and modifications made according to the technical idea of the present invention should be included in the protection scope of the claims of the present invention.