阅读说明：本技术 一种基于微透镜阵列的多光谱成像系统及图像重建方法 (Multispectral imaging system based on micro-lens array and image reconstruction method ) 是由 吴衡 马建文 罗劭娟 陈梅云 赵艮平 程良伦 王涛 于 2020-07-28 设计创作，主要内容包括：本申请公开了一种基于微透镜阵列的多光谱成像系统及图像重建方法,其通过采用微透镜阵列与线性渐变滤光片,可以对被测目标物实现不同连续波段的成像且分割成多个子图像,并且,线性渐变滤光片相对于微透镜阵列呈一定角度倾斜设置,以使得面阵CCD探测器获取到高质量且高分辨率的图像,并通过最大后验估计方法,可以快速重建出高质量的图像。同时,本申请实施例仅采用面阵CCD探测器、微透镜阵列与线性渐变滤光片就可以实现对被测目标物采集图像数据,而又线性渐变滤光片安装方便,降低了硬件成本且结构紧凑。(The application discloses multispectral imaging system and image reconstruction method based on a micro-lens array, which can realize imaging of different continuous wave bands on a detected target object and divide the imaging into a plurality of sub-images by adopting the micro-lens array and a linear gradient filter, and the linear gradient filter is obliquely arranged at a certain angle relative to the micro-lens array so that an area array CCD detector obtains an image with high quality and high resolution, and can rapidly reconstruct the image with high quality by a maximum posterior estimation method. Meanwhile, the embodiment of the application can realize the image data acquisition of the detected target object only by adopting the area array CCD detector, the micro lens array and the linear gradient filter, and the linear gradient filter is convenient to install, reduces the hardware cost and has a compact structure.)

1. A multi-spectral imaging system based on a microlens array, comprising: the device comprises a calculation module, an area array CCD detector, a micro-lens array and a linear gradient filter;

the area array CCD detector, the micro lens array and the linear gradient filter are sequentially arranged along a light path, so that incident light rays sequentially pass through the linear gradient filter and the micro lens array to reach the area array CCD detector;

the center of a target surface of the area array CCD detector is arranged at the focus of the micro lens array, the linear gradient filter is arranged at a preset distance d relative to the micro lens array, and the linear gradient filter is rotated clockwise so as to be obliquely arranged relative to the micro lens array, and the size of the linear gradient filter is consistent with that of the micro lens array;

and the computing module is connected with the area array CCD detector and is used for reconstructing the image of the detected target object shot by the area array CCD detector based on a prestored maximum posterior estimation image reconstruction algorithm.

2. The microlens array based multispectral imaging system as recited in claim 1, wherein the microlens array comprises a plurality of microlenses that are coplanar, the plurality of microlenses being uniformly distributed, the microlenses being spherical lenses.

3. The microlens array based multispectral imaging system as recited in claim 2, wherein the refractive index n of the microlenses is 1.52mm, the diameter D of the microlenses is 2.3mm, and the spacing l between adjacent microlenses is 0.0625 mm.

4. The microlens array based multispectral imaging system as recited in claim 1, wherein the focal length f of the microlens array is 6 mm.

5. The microlens array based multispectral imaging system as recited in claim 1, wherein the linear graded filter is disposed at a predetermined distance d of 0.5mm from the microlens array.

6. The microlens array based multispectral imaging system as recited in claim 1, wherein the linear graded filter is horizontally angled at 7.125 ° with respect to the microlens array.

7. An image reconstruction method based on the multispectral imaging system based on the microlens array as claimed in any one of claims 1 to 6, comprising the following steps:

s1: the emergent light of the target object to be detected is incident to the linear gradient filter, and the emergent light is divided into light rays with different wave bands through the linear gradient filter;

s2: light rays with different wave bands are obliquely incident into each micro lens of the micro lens array, the micro lens array is an m multiplied by n array, and then the light rays incident from each micro lens form images on a target surface of the area array CCD detector and form images of m multiplied by n detected target objects;

s3: and reconstructing the image of the detected target object acquired by the area array CCD detector through a computing module based on a prestored maximum posterior estimation image reconstruction algorithm.

8. The image reconstruction method according to claim 7, wherein the step S3 specifically includes:

s301: dividing the images of m multiplied by n measured objects acquired by the area array CCD detector into corresponding sub-images, and recording each sub-image as S_iM × n sub-images can be obtained. From this, a sequence of partial images S can be obtained, denoted by

S＝[S₁,S₂,...,S_i,...,S_m*n]；

S302: selecting any sub-image at the most middle position of the sub-image sequence S as a target image S_fAnd connecting the other sub-images with the target imageRegistering the images to obtain a new registered sub-image sequence Q ═ Q [ < Q >₁,Q₂,...,Q_i,Q_f,...,Q_m*n]Wherein Q is_iFor the i-th registered sub-image S in the sub-image sequence S_i，Q_fIs a target image S_f；

S303: by means of the sub-image sequence Q, a mathematical model is established of,

the formula is simplified to obtain Z ═ HX + N, wherein Z ═ Q^TZ is a reconstructed sub-image, H is an image transformation matrix, X is an image to be reconstructed, and N is a noise vector;

s304: obtaining the target image by optimizing a conditional probability density function between X and Z, the conditional probability density function being

Wherein M is^-1E is an autocorrelation matrix, T is a transpose of the matrix;

iterative computation is carried out on the formula to obtain

Technical Field

The application relates to the technical field of multispectral imaging, in particular to a multispectral imaging system based on a micro-lens array and a corresponding image reconstruction method.

Background

The spectral imaging technology is an important component in the technical field of optical imaging and detection. The spectral imaging technology and the optical imaging technology are integrated, and the spectral information and the spatial characteristic information of the measured object can be simultaneously obtained. The spectral imaging technology has the advantage of multispectral resolution, and can directly identify the target object from the space, so that the method has extremely high application value in the aspects of target identification, natural disaster early warning, agricultural product detection and the like.

The currently mainstream multispectral imaging technology includes dispersive type, interference type, and optical filter type. The dispersive multispectral imaging technology utilizes prism or grating light splitting and then imaging by an imaging system. The interference type multispectral imaging technology detects an interference pattern of a measured object by using an interferometer, and then obtains spectral information through Fourier transform calculation. The dispersive and interference multispectral imaging systems have complex structures and high requirements on hardware. The filter type multispectral imaging technology is characterized in that a filter is added into an imaging system for light splitting to generate light with various spectrums, and then imaging is carried out. Compared with a dispersion type and an interference type, the optical filter type multispectral imaging system is simple in structure, high in spatial resolution and spectral resolution and wide in application prospect in the actual civil and military fields. However, the existing optical filter type multispectral imaging system has the problems of poor imaging quality, low resolution, high hardware requirement and the like. Therefore, an optical filter type multispectral imaging system with compact structure, good imaging quality and low hardware cost is urgently needed to be developed.

Disclosure of Invention

The application provides a multispectral imaging system and an image reconstruction method based on a micro-lens array, which are used for solving the technical problems of poor imaging quality, high hardware cost and complex structure in the prior art.

In view of the above, the present application provides in a first aspect a multispectral imaging system based on a microlens array, comprising: the device comprises a calculation module, an area array CCD detector, a micro-lens array and a linear gradient filter;

the area array CCD detector, the micro lens array and the linear gradient filter are sequentially arranged along a light path, so that incident light rays sequentially pass through the linear gradient filter and the micro lens array to reach the area array CCD detector;

the center of a target surface of the area array CCD detector is arranged at the focus of the micro lens array, the linear gradient filter is arranged at a preset distance d relative to the micro lens array, and the linear gradient filter is rotated clockwise so as to be obliquely arranged relative to the micro lens array, and the size of the linear gradient filter is consistent with that of the micro lens array;

and the computing module is connected with the area array CCD detector and is used for reconstructing the image of the detected target object shot by the area array CCD detector based on a prestored maximum posterior estimation image reconstruction algorithm.

Preferably, the microlens array comprises a plurality of coplanar microlenses, the microlenses are uniformly distributed, and the microlenses are spherical lenses.

Preferably, the refractive index n of the microlens is 1.52mm, the diameter D of the microlens is 2.3mm, and the distance l between adjacent microlenses is 0.0625 mm.

Preferably, the focal length f of the microlens array is 6 mm.

Preferably, the linear graded filter is disposed at a preset distance d of 0.5mm with respect to the microlens array.

Preferably, the horizontal included angle of the linear graded filter with respect to the microlens array is 7.125 °.

The application also provides an image reconstruction method, and the multispectral imaging system based on the micro-lens array comprises the following steps:

s1: the emergent light of the target object to be detected is incident to the linear gradient filter, and the emergent light is divided into light rays with different wave bands through the linear gradient filter;

s2: light rays with different wave bands are obliquely incident into each micro lens of the micro lens array, the micro lens array is an m multiplied by n array, and then the light rays incident from each micro lens form images on a target surface of the area array CCD detector and form images of m multiplied by n detected target objects;

s3: and reconstructing the image of the detected target object acquired by the area array CCD detector through a computing module based on a prestored maximum posterior estimation image reconstruction algorithm.

Preferably, the step S3 specifically includes:

s301: dividing the images of m multiplied by n measured objects acquired by the area array CCD detector into corresponding sub-images, and recording each sub-image as S_iM × n sub-images can be obtained. From this, a sequence of partial images S can be obtained, denoted by

S＝[S₁,S₂,...,S_i,...,S_m*n]；

S302: selecting any sub-image at the most middle position of the sub-image sequence S as a target image S_fAnd registering other sub-images with the target image to obtain a new registered sub-image sequence Q (Q ═ Q)₁,Q₂,...,Q_i,Q_f,...,Q_m*n]Wherein Q is_iFor the i-th registered sub-image S in the sub-image sequence S_i，Q_fIs a target image S_f；

S303: by means of the sub-image sequence Q, a mathematical model is established of,

the formula is simplified to obtain Z ═ HX + N, wherein Z ═ Q^TZ is the reconstructed sub-image, H is the image transformation matrix, and X is the image to be reconstructedReconstructing an image, N being a noise vector;

s304: obtaining the target image by optimizing a conditional probability density function between X and Z, the conditional probability density function being

Wherein M is^-1E is an autocorrelation matrix, T is a transpose of the matrix;

iterative computation is carried out on the formula to obtain

And obtaining a reconstructed image of the object to be detected.

According to the technical scheme, the embodiment of the application has the following advantages:

the embodiment of the application provides a multispectral imaging system and an image reconstruction method based on a micro-lens array, and the multispectral imaging system and the image reconstruction method can realize imaging of different continuous wave bands on a detected target object and divide the imaging into a plurality of sub-images by adopting the micro-lens array and a linear gradient filter, and the linear gradient filter is obliquely arranged at a certain angle relative to the micro-lens array, so that an area array CCD detector obtains an image with high quality and high resolution, and the image with high quality can be rapidly reconstructed by a maximum posterior estimation method. Meanwhile, the embodiment of the application can realize the image data acquisition of the detected target object only by adopting the area array CCD detector, the micro lens array and the linear gradient filter, and the linear gradient filter is convenient to install, reduces the hardware cost and has a compact structure.

Drawings

Fig. 1 is a schematic structural diagram of a multispectral imaging system based on a microlens array according to an embodiment of the present application;

fig. 2 is a schematic structural diagram of a microlens array of a multispectral imaging system based on a microlens array according to an embodiment of the present application;

fig. 3 is a flowchart of an image reconstruction method according to an embodiment of the present application.

Detailed Description

In order to make the technical solutions of the present application better understood, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.