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 共查询到10条相似文献,搜索用时 93 毫秒
1.
孟凡欣  邢中阳  许中杰  程湘爱 《强激光与粒子束》2022,34(1):011010-1-011010-9
干涉成像光谱技术是利用光的干涉原理获取目标光谱信息的一种成像技术。为研究其在强光下的干扰效果和机理,以大孔径静态成像光谱仪为典型对象,开展了相关仿真实验研究。以实际地物的图像和光谱信息为对象,仿真生成了原始干涉成像图案,并模拟830 nm单波长激光和超连续谱激光两种干扰源,分别研究不同辐照强度下的典型干扰效果,分析时假设光谱角大于30°时原始光谱信息丢失。基于本文的仿真模型,得到的相关结果表明,在830 nm的单波长激光干扰情况下,当干扰与目标成像峰值之比大于0.2∶1时原始光谱信息无法正确复原(光谱角大于30°),但模拟加入830 nm滤光片后,干扰效果被有效滤除。在超连续谱激光干扰情况下,不考虑饱和阈值时光谱角数值最终稳定在21°;考虑探测器饱和阈值为目标成像强度峰值3倍时,干扰与目标成像峰值之比大于2.1∶1时,原始光谱信息便无法分辨。该研究可能为同类型光谱仪的激光辐照效应和损伤机理的后续研究,以及光谱成像系统的激光防护和性能优化提供参考。  相似文献   

2.
An acousto-optic tunable filter that is insensitive to the polarization of incident light is studied both theoretically and experimentally. The fundamental possibility of designing an acousto-optic filter of nonpolarized light is demonstrated. The filter operates in the visible range of electromagnetic waves with λ=480–750 nm and provides a high spatial and temporal resolution. The number of resolvable spots of the filtered image reaches a value of 400×400 with the spectral bandwidth of the device being Δλ=1.7 nm. The results of the processing of optical images formed by arbitrarily polarized light beams are discussed. An acousto-optic filter based on a TeO2 crystal can be used in optics and spectroscopy in the processing of light beams with an arbitrary polarization, as well as in analyzing optical images formed by light beams whose polarization varies with time.  相似文献   

3.
This work aims the detection of the histopathologic alterations of in vitro human gastric mucosa using spectral informations from laser-induced fluorescence spectroscopy (LIFS) technique with excitation at 488 nm (argon laser). A total of 108 biopsies with endoscopic diagnosis of gastritis and gastric cancer were obtained at the antral gastric region, from 35 patients with dyspeptic digestive complaints. The biopsies were collected during the endoscopic examination. On each biopsy fragment the autofluorescence spectrum was collected in two random points, through a fiber-optic catheter coupled to the excitation laser. The fluorescence emission spectra collected by the fibers were directed to the spectrograph and detected by the CCD camera. The spectra were then separated in groups (N, normal; LI, light inflammation; MI, moderated inflammation; CA, adenocarcinoma), based on the histopathology. The ratio between the emission wavelengths 550 and 600 nm was used as a diagnostic parameter. Analysis of fluorescence spectra was able to identify the normal tissue from adenocarcinoma lesions with 100% of sensibility and specificity. The ratio intensities between inflammation (light and moderated), although presented significantly statistical differences when compared to the normal mucosa, do not furnish enough sensibility and specificity for use as an identification method due to high variations. LIFS, with excitation of 488 nm, could be used in the differentiation of normal tissue and neoplasic lesions, assisting a less invasive diagnosis.  相似文献   

4.
在Bruker ER 200D ESR 谱仪上安装一套自制的谱-空间2D ESR成像系统,这套系统由一对梯度场线圈、电源、微机及图像重建程序组成. 用滤波反投影图像重建方法,实现了两种自由基样品的谱-空间2D ESR成像,由2D 图像得到样品中自由基的自旋密度空间分布及相应的波谱参数. 讨论了成像参数与图像精度的关系.  相似文献   

5.
Regularities of the wide-aperture mode of light diffraction by acoustic waves in crystals with different values of birefringence are considered. The diffraction has been investigated theoretically and experimentally with the aim of applying it in acousto-optic filters used in processing uncollimated optical beams and images. It is proved that the main filtration parameters depend on the birefringence of crystals used in processing luminous fluxes. By the example of wide-aperture filters based on paratellurite, magnesium fluoride, and potassium dihydrogen phosphate crystals, it is shown that the choice of crystals with high birefringence may increase the maximum attainable angular aperture and throughput of devices. It is also proved that application of crystalline compounds of mercury and tellurium (characterized by high optical anisotropy) in filters increases spectral resolution and improves the quality of filtered images.  相似文献   

6.
Objective assessment of gastrointestinal mucosal color is extremely important in the endoscopic diagnosis of digestive tract disease. In this paper, we propose a method to clarify the spectral characteristics of gastric and colon cancer. A large number of spectral reflectance data of mucous membrane are measured by the endoscopic spectroscopy system (ESS) in the National Cancer Center Hospital East, Kashiwa, Japan and the Department of Internal Medicine, Self-Defense Force Center Hospital, Tokyo, Japan. We assume that early cancer appears primarily in the spectral data of short wavelength, because it is usually present in a superficial cell where short wavelength light is scattered more strongly than long wavelength light. To identify the features in the short wavelength components, the spectral reflectance was divided by the reflectance of a long wavelength. We investigated the possibility of distinguishing early cancer from normal spectral data through statistical analysis, employing the projection axis as the mean difference between them. Early cancer and normal spectral data were projected on the projection axis, and the Student’s T-test was applied to evaluate the mean of the distribution between these data.  相似文献   

7.
Xiaopeng Deng  Daomu Zhao 《Optik》2012,123(10):924-927
A new method for larger size images recognition is proposed based on high-pass filtering and frequency spectrum correlation. The input images are first filtered by a high-pass filter. Then the filtered input images, which are overlapped rather than displaced from each other in the input plane, serve as the input images for frequency spectrum correlator. As a result, only one sharp correlation peak yields in the center of output plane when the target image matches with the reference image. More importantly, the method is especially suitable for larger size image recognition because of the input and correlation ways, which ensures better utilization of the space-bandwidth product and efficient utilization of the spatial light modulator and detector. Computer simulation results are presented to demonstrate the feasibility and effectiveness of this method.  相似文献   

8.
Point pattern matching is an essential step in many image processing applications.This letter investigates the spectral approaches of point pattern matching,and presents a spectral feature matching algorithm based on kernel partial least squares(KPLS).Given the feature points of two images,we define position similarity matrices for the reference and sensed images,and extract the pattern vectors from the matrices using KPLS,which indicate the geometric distribution and the inner relationships of the feature points.Feature points matching are done using the bipartite graph matching method.Experiments conducted on both synthetic and real-world data demonstrate the robustness and invariance of the algorithm.  相似文献   

9.
Flow diagnostics based on molecular Rayleigh scattering are discussed along with the results of a feasibility study to non-intrusively measure flow properties in a small supersonic wind tunnel. The technique uses an injection seeded, frequency doubled Nd:YAG laser tuned to an absorption band of iodine. The molecular Rayleigh scattered light is filtered with an iodine cell to block light at the laser frequency. The Doppler-shifted Rayleigh scattered light that passes through the iodine cell is analyzed with a planar mirror Fabry-Perot interferometer used in a static imaging mode. An intensified CCD camera is used to record the images. The images are analyzed at several subregions, where the flow properties are determined. Each image is obtained with a single laser pulse, giving instantaneous measurements.  相似文献   

10.
Optical imaging of an exposed cortex for brain function measurement is an attractive method for both clinical and physiological investigations. Spectral imaging of the exposed cortical tissue enables measurement of the activity-dependent changes in oxy- and deoxy-haemoglobin independently. Since the diffusely reflected light from the exposed cortex is highly scattered in the cortical tissue, the wavelength dependence of the optical properties of the tissue is likely to affect the images of oxy- and deoxy-haemoglobin changes obtained from the spectral images. In this study, the spectral images of the model of exposed cortical tissue are calculated by Monte Carlo simulation to investigate the influence of blurring by tissue scattering on the brain function measurement by the imaging. The images of the change in oxy- and deoxy-haemoglobin obtained from the spectral images at near infrared wavelengths are broadened and blurred due to the scattering in the cortical tissue. The influence of cross talk is more significant in the image calculated from the spectral images at the visible wavelengths. Inappropriate choice of the spectral range of images might increase cross talk and error in the images of oxy- and deoxy-haemoglobin changes.  相似文献   

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