| CPC G01K 11/12 (2013.01) [G01K 3/14 (2013.01)] | 15 Claims |
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1. A laser-induced phosphorescence flow field three-dimensional temperature field measurement method based on a multispectral light field imaging system, wherein the multispectral light field imaging system comprises a primary lens, a microlens array, a first relay lens, a dichroic lens, a second relay lens, a third relay lens, a first image sensor, a first filter, a second image sensor and a second filter, wherein the microlens array is located at an image plane of the primary lens; a distance between the first relay lens and an equivalent plane of the microlens array is f+F, wherein f refers to a focal length of the microlens array, and F is a focal length of the first relay lens; the first relay lens together with the second relay lens and the third relay lens forms a 1:1 relay lens group imaging system on a spectral band first light path and a spectral band second light path respectively; the dichroic lens forms an included angle of 45° with a light axis; the first image sensor is located at a focal plane of the second relay lens, and the second image sensor is located at a focal plane of the third relay lens;
wherein the laser-induced phosphorescence flow field three-dimensional temperature field measurement method comprises:
sensing a light field with said multispectral light field imaging system such that light field images of the light field are collected by the first image sensor and the second image sensor respectively through the first relay lens and the dichroic lens and through one of the second relay lens and the third relay lens respectively;
based on the light field images, obtaining a three-dimensional spectral intensity distribution corresponding to the light field images; and
based on the three-dimensional spectral intensity distribution, obtaining a three-dimensional temperature distribution by an intensity ratio method;
wherein based on the light field images, obtaining the three-dimensional spectral intensity distribution corresponding to the light field images comprises:
based on the light field images, establishing a correspondence equation set of a position of a target object, a spectral intensity of the target object, and a light field image;
based on characteristics of a tangent-circle imaging region of a light field camera, simplifying the correspondence equation set by culling invalid pixels of the light field images and corresponding weight coefficients;
based on first-time Simultaneous Algebraic Reconstruction Technique (SART) algorithm, performing preliminary reconstruction;
by using a maximum inter-class variance method, performing binarization on a preliminary reconstruction result, setting a voxel spectral intensity value below a binarization threshold to zero and obtaining a voxel column vector without particle overlap;
based on a correspondence between a voxel column vector number and a voxel three-dimensional coordinate, reducing the voxel column vector to a three-dimensional voxel matrix, and obtaining a voxel of center of gravity of a three-dimensional connected body within the three-dimensional voxel matrix by using Gaussian fitting;
based on the center of gravity of the three-dimensional connected body, calculating the voxels of the centers of gravity of all three-dimensional connected bodies within the three-dimensional voxel matrix, marking three-dimensional coordinates of the voxels of the centers of gravity, culling all voxels other than the voxels of the centers of gravity in the three-dimensional voxel matrix to obtain a simplified three-dimensional voxel matrix, reducing the simplified three-dimensional voxel matrix to a simplified voxel column vector, and synchronizing a weigh coefficient matrix to a simplified weight coefficient matrix, so as to obtain a simplified light field tomographic reconstruction equation;
performing second-time SART tomographic reconstruction on the simplified tomographic reconstruction equation to obtain a target voxel column vector; and
based on a correspondence between three-dimensional coordinate of voxel of center of gravity and voxel column vector number, reducing the target voxel column vector to a target flow field control body three-dimensional voxel matrix.
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