机器视觉中均匀照明成像的LED环形阵列设计 
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LED Ring Array Design for Uniform Illumination Imaging in Machine Vision
1 复旦大学信息科学与工程学院电光源研究所, 上海 200433
2 复旦大学工程与应用技术研究院, 上海 200433
图 & 表
图 1. 表面反射的几何形状
Fig. 1. Geometry of surface reflection
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图 2. LED环形阵列照明模型示意图
Fig. 2. Schematic of LED ring array illumination model
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图 3. LED环形阵列照明设计流程图
Fig. 3. Flow chart of LED ring array illumination design
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图 4. ρ=0°时单环不同半径的照度分布。(a)~(e)照度均匀度分别是23.85%, 22.50%, 20.35%, 17.79%, 15.51%
Fig. 4. Illumination distribution of different radius with ρ=0° in single ring. (a)--(e) Illumination uniformity is 23.85%, 22.50%, 20.35%, 17.79%, and 15.51%, respectively
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图 5. 组合A3-B1-C1-D1对应的归一化后的照度分布和中间线的照度分布。(a)照度分布;(b)中间线的照度分布
Fig. 5. Normalized illumination distribution and illumination distribution of central line corresponding to the combination of A3-B1-C1-D1. (a) Illumination distribution; (b) illumination distribution of central line
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图 6. 均匀度与照射角度的关系
Fig. 6. Relation between uniformity and irradiating angle
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图 7. 不同照射角度下的光强值。(a) ρ=0°;(b) ρ=20°;(c) ρ=40°
Fig. 7. Light intensity at different irradiating angles. (a) ρ=0°; (b) ρ=20°; (c) ρ=40°
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图 8. 20°照射角下对应的归一化照度。(a) 2D照度分布图;(b)中间线照度分布图;(c) 3D照度分布图
Fig. 8. Normalized illumination corresponding to irradiating angle of 20°. (a) 2D map of illumination distribution; (b) illumination distribution map of central line; (c) 3D map of illumination distribution
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图 9. 实验系统示意图。(a)设计的LED环形阵列;(b)实验装置
Fig. 9. Schematic of experimental system. (a) Designed LED ring array; (b) experimental setup
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图 10. 不同照明环境下的3D样品成像效果。(a)样品图像;(b)最优光环境下拍摄的图像;(c)~(f)非均匀光环境下的图像
Fig. 10. 3D sample imaging effect under different illuminating conditions. (a) Sample image; (b) image taken in optimal light environment; (c)--(f) images in non-uniform light environment
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图 11. 样品细节图。(a)最优光环境下的3D样品图像;(b)对应的灰度等级图
Fig. 11. Sample details. (a) 3D sample image in optimal light environment; (b) corresponding gray level map
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图 12. 最优光环境下对应的光斑和灰度分布。(a)光斑;(b)中心区域的3D灰度等级分布
Fig. 12. Corresponding light spot and gray distribution in optimal light environment. (a) Light spot; (b) 3D gray level distribution in central area
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表 1ρ=0°时,LED环形阵列照度均匀度分布
Table1. Illumination uniformity distribution of LED ring array at ρ=0°
| β | r=30 mm | r=70 mm | r=110 mm |
|---|
| 8 | 63.57% | 63.07% | 57.65% | | 16 | 71.58% | 69.30% | 66.71% |
|
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表 2机器视觉光环境影响因子及其水准设置
Table2. Influence factors and level setting for machine vision light environment
| Symbol | Parameter | Number of levels | Level 1 | Level 2 | Level 3 |
|---|
| A | β | 3 | 8 | 12 | 16 | | B | r' /mm | 3 | 20 | 30 | 40 | | C | α | 3 | 3 | 4 | 5 | | D | ρ /(°) | 3 | 15 | 30 | 45 |
|
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表 3仿真模拟直交表
Table3. Simulation of direct intersection table
| s' | A | B | C | D | Illumination uniformity /% | ε |
|---|
| 1 | 1 | 1 | 1 | 1 | 80.76 | 38.14 | | 2 | 1 | 2 | 2 | 2 | 79.62 | 38.02 | | 3 | 1 | 3 | 3 | 3 | 77.91 | 37.83 | | 4 | 2 | 1 | 2 | 3 | 80.82 | 38.15 | | 5 | 2 | 2 | 3 | 1 | 81.40 | 38.21 | | 6 | 2 | 3 | 1 | 2 | 81.17 | 38.19 | | 7 | 3 | 1 | 3 | 2 | 80.84 | 38.15 | | 8 | 3 | 2 | 1 | 3 | 80.82 | 38.15 | | 9 | 3 | 3 | 2 | 1 | 82.29 | 38.31 |
|
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表 4不同水准值对应的S/N值
Table4. Corresponding S/N value of different level values
| Control level | A | B | C | D |
|---|
| 1 | 37.9987 | 38.1489 | 38.1607 | 38.2211 | | 2 | 38.1836 | 38.1278 | 38.1593 | 38.1203 | | 3 | 38.2033 | 38.1089 | 38.0656 | 38.0442 |
|
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表 5均匀性的ANOVA结果
Table5. ANOVA results of uniformity
| Parameter | A | B | C | D |
|---|
| Sd | 0.0255 | 0.0008 | 0.0059 | 0.0158 | | Contribution /% | 53.10 | 1.67 | 12.38 | 32.85 |
|
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表 6测试灯具参数
Table6. Parameters of test luminaire
| Parameter | Value |
|---|
| Total number of LEDs | 96 | | α | 3 | | ρ /(°) | 20 | | Radius of inner ring /mm | 35 | | Radius of outer ring /mm | 50 |
|
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史晨阳, 林燕丹. 机器视觉中均匀照明成像的LED环形阵列设计[J]. 光学学报, 2020, 40(20): 2011003. Chenyang Shi, Yandan Lin. LED Ring Array Design for Uniform Illumination Imaging in Machine Vision[J]. Acta Optica Sinica, 2020, 40(20): 2011003.
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