In order to find an effective method of detecting thrips defect on green-peel citrus, a defect segmentation method was developed using a single threshold value based on combination of characteristic wavelengths princi...In order to find an effective method of detecting thrips defect on green-peel citrus, a defect segmentation method was developed using a single threshold value based on combination of characteristic wavelengths principal component analysis （PCA） and B-spline lighting correction method in this study. At first, four characteristic wavelengths （523, 587, 700 and 768 nm） were obtained using PCA of Vis-NIR （visible and near-infrared） bands and analysis of weighting coefficients; secondarily, PCA was performed using characteristic wavelengths and the second principal component （PC2） was selected to classify images; then, B-spline lighting correction method was proposed to overcome the influence of lighting non-uniform on citrus when thrips defect was segmented; finally, thrips defect on citrus was extracted by global threshold segmentation and morphological image processing. The experimental results show that thrips defect in citrus can be detected with an accuracy of 96.5% by characteristic wavelengths PCA and B-spline lighting correction method. This study shows that thrips defect on green-peel citrus can be effectively identified using hyperspectral imaging technology.展开更多
Absorption imaging is a fundamental technique for quantitatively extracting information from ultracold atom experiments.Since ultracold^(6)Li atoms are prepared and detected under high magnetic fields,the suitable det...Absorption imaging is a fundamental technique for quantitatively extracting information from ultracold atom experiments.Since ultracold^(6)Li atoms are prepared and detected under high magnetic fields,the suitable detuning of the probe light can reach the GHz level compared to zero-field imaging.Therefore,based on the energy level structure of^(6)Li atoms and the requirements of subsequent experiments,we design a high-field imaging system with a large frequency range and good robustness,starting from the rationality of the optical layout design and employing offset locking techniques.This imaging system covers the entire crossover region from Bose–Einstein condensate to Bardeen–Cooper–Schrieffer(BEC–BCS)and realizes free switching between zero-field and high-field imaging.Additionally,by introducing a proportionality coefficient to correct for the intensity fluctuations of the probe light,we mitigate its disturbance on the statistical measurement of particle numbers in the experiment.This work not only provides a design reference for other quantum gas experiments requiring absorption imaging under strong bias magnetic fields,but also serves as an important reference for improving the imaging performance.展开更多
A new type of light fiehl display is proposed using a head-mounted display （HMD） and a micro structure array （MSA, lens array or pinhole array）. Each rendering point emits abundant rays from different directions i...A new type of light fiehl display is proposed using a head-mounted display （HMD） and a micro structure array （MSA, lens array or pinhole array）. Each rendering point emits abundant rays from different directions into the viewer＇s pupil, and at one time the dense light field is generated inside the exit pupil of the HMD through the eyepiece. Therefore, the proposed method not only solves the problem of accommodation and convergence conflict in a traditional HMD, but also drastically reduces the huge data in real three-dimensional （3D） display. To demonstrate the proposed method, a prototype is developed, which is capable of giving the observer a real perception of depth.展开更多
基金supproted by the National Key Technology R&D Program of China(2012BAF07B05)
文摘In order to find an effective method of detecting thrips defect on green-peel citrus, a defect segmentation method was developed using a single threshold value based on combination of characteristic wavelengths principal component analysis （PCA） and B-spline lighting correction method in this study. At first, four characteristic wavelengths （523, 587, 700 and 768 nm） were obtained using PCA of Vis-NIR （visible and near-infrared） bands and analysis of weighting coefficients; secondarily, PCA was performed using characteristic wavelengths and the second principal component （PC2） was selected to classify images; then, B-spline lighting correction method was proposed to overcome the influence of lighting non-uniform on citrus when thrips defect was segmented; finally, thrips defect on citrus was extracted by global threshold segmentation and morphological image processing. The experimental results show that thrips defect in citrus can be detected with an accuracy of 96.5% by characteristic wavelengths PCA and B-spline lighting correction method. This study shows that thrips defect on green-peel citrus can be effectively identified using hyperspectral imaging technology.
基金supported by the National Natural Science Foundation of China(Grant Nos.92365208 and 11920101004)the National Key Research and Development Program of China(Grant Nos.2021YFA0718300 and 2021YFA1400900).
文摘Absorption imaging is a fundamental technique for quantitatively extracting information from ultracold atom experiments.Since ultracold^(6)Li atoms are prepared and detected under high magnetic fields,the suitable detuning of the probe light can reach the GHz level compared to zero-field imaging.Therefore,based on the energy level structure of^(6)Li atoms and the requirements of subsequent experiments,we design a high-field imaging system with a large frequency range and good robustness,starting from the rationality of the optical layout design and employing offset locking techniques.This imaging system covers the entire crossover region from Bose–Einstein condensate to Bardeen–Cooper–Schrieffer(BEC–BCS)and realizes free switching between zero-field and high-field imaging.Additionally,by introducing a proportionality coefficient to correct for the intensity fluctuations of the probe light,we mitigate its disturbance on the statistical measurement of particle numbers in the experiment.This work not only provides a design reference for other quantum gas experiments requiring absorption imaging under strong bias magnetic fields,but also serves as an important reference for improving the imaging performance.
基金partially supported by the National Basic Research Program of China(No.2013CB328805)the National Science Foundation of China(NSFC,No.61205024,61178038)the National Key Technology R&D Program(No.2012BAH64F03)
文摘A new type of light fiehl display is proposed using a head-mounted display （HMD） and a micro structure array （MSA, lens array or pinhole array）. Each rendering point emits abundant rays from different directions into the viewer＇s pupil, and at one time the dense light field is generated inside the exit pupil of the HMD through the eyepiece. Therefore, the proposed method not only solves the problem of accommodation and convergence conflict in a traditional HMD, but also drastically reduces the huge data in real three-dimensional （3D） display. To demonstrate the proposed method, a prototype is developed, which is capable of giving the observer a real perception of depth.
