Jifan Liu, Yanhua Ma, Lei Zhang, Jianyu Wang, R. Shu
The hyperspectral imager is a kind of camera that can image objects in many narrow spectral bands, and acousto-optic tunable filters (AOTFs) can be used as the optical filtering elements in such instruments. AOTFs have many advantages such as solid-state, small size, good environmental adaptability, programmable, electronically control and so on, which are suitable for space exploration. For instance, AOTFs have been used in Mars and Venus detection. However, more advantages of AOTFs can be utilized in spectral detection, such as random wavelength access and configurable spectral resolution, and more flexible imagers can be expected with these characteristics. As a result, a new hyperspectral imager based on AOTF has been realized. It can not only take images in the spectral range of 460~1100nm with more than one hundred narrow bands, but also allow users to select any set of bands and configure the spectral resolution in a certain range just by computer commands. To do so, a multi-channel RF generation system is developed to drive the AOTF. When multi RF frequencies are applied to the AOTF simultaneously, not only the central wavelength, but also the bandwidth and the passband shape of the selected band, can be controlled by configuring the RF signals. Such capability enhances the flexibility of hyperspectral imaging, but the increased number of configurable variables complicates the course of calibration, so some specific calibration setups and methods are needed. In this paper, the laboratory calibration of the imager is introduced, and some results are presented and analyzed.
{"title":"Calibration of an AOTF hyperspectral imager with configurable spectral selectivity","authors":"Jifan Liu, Yanhua Ma, Lei Zhang, Jianyu Wang, R. Shu","doi":"10.1117/12.902306","DOIUrl":"https://doi.org/10.1117/12.902306","url":null,"abstract":"The hyperspectral imager is a kind of camera that can image objects in many narrow spectral bands, and acousto-optic tunable filters (AOTFs) can be used as the optical filtering elements in such instruments. AOTFs have many advantages such as solid-state, small size, good environmental adaptability, programmable, electronically control and so on, which are suitable for space exploration. For instance, AOTFs have been used in Mars and Venus detection. However, more advantages of AOTFs can be utilized in spectral detection, such as random wavelength access and configurable spectral resolution, and more flexible imagers can be expected with these characteristics. As a result, a new hyperspectral imager based on AOTF has been realized. It can not only take images in the spectral range of 460~1100nm with more than one hundred narrow bands, but also allow users to select any set of bands and configure the spectral resolution in a certain range just by computer commands. To do so, a multi-channel RF generation system is developed to drive the AOTF. When multi RF frequencies are applied to the AOTF simultaneously, not only the central wavelength, but also the bandwidth and the passband shape of the selected band, can be controlled by configuring the RF signals. Such capability enhances the flexibility of hyperspectral imaging, but the increased number of configurable variables complicates the course of calibration, so some specific calibration setups and methods are needed. In this paper, the laboratory calibration of the imager is introduced, and some results are presented and analyzed.","PeriodicalId":355017,"journal":{"name":"Photoelectronic Detection and Imaging","volume":"25 3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123691632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Q. Duanmu, Guozheng Wang, Ye Li, Yang Wang, Hongchang Cheng, Xulei Qin, Zhenhua Jiang, D. Jiang
A Silicon microchannel arrays with the very high aspect ratio was prepared by the photo-assisted electrochemical etching process. The mechanism of silicon anisotropy etching, the process parameters, the inducing pit arrays and the channel morphology were investigated, and the condition of etching current density for steady microchannel growth was discussed. The continuous SiO2 thin film dynode was fabricated by LPCVD process. The insulation, conductive and electron emission layer of the dynodes were studied and prepared. We obtained the samples of silicon microchannel plate with 25 mm of the plate diameter, 4-6 μm of channel side size, 1-2 μm of the channel space, more than 40 of aspect ratio, 7° channel bias angle, and 165 of the electron gain at 680V working voltage. The experimental study on silicon microchannel plate indicates that the process of Silicon microchannel plate in this paper is feasible.
{"title":"Experimental investigation on silicon microchannel plate electron multiplier","authors":"Q. Duanmu, Guozheng Wang, Ye Li, Yang Wang, Hongchang Cheng, Xulei Qin, Zhenhua Jiang, D. Jiang","doi":"10.1117/12.897420","DOIUrl":"https://doi.org/10.1117/12.897420","url":null,"abstract":"A Silicon microchannel arrays with the very high aspect ratio was prepared by the photo-assisted electrochemical etching process. The mechanism of silicon anisotropy etching, the process parameters, the inducing pit arrays and the channel morphology were investigated, and the condition of etching current density for steady microchannel growth was discussed. The continuous SiO2 thin film dynode was fabricated by LPCVD process. The insulation, conductive and electron emission layer of the dynodes were studied and prepared. We obtained the samples of silicon microchannel plate with 25 mm of the plate diameter, 4-6 μm of channel side size, 1-2 μm of the channel space, more than 40 of aspect ratio, 7° channel bias angle, and 165 of the electron gain at 680V working voltage. The experimental study on silicon microchannel plate indicates that the process of Silicon microchannel plate in this paper is feasible.","PeriodicalId":355017,"journal":{"name":"Photoelectronic Detection and Imaging","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126835010","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Due to the insufficient employment of the correlation among wavelet coefficients, existing significance coding methods can't reduce entropy redundancy efficiently. In order to solve this problem, a significance context model based on intraband and interband correlation is proposed. The model uses neighbor coefficients in the same subband and a parent coefficient in the lower subband as context to predict the current coding coefficient. Neighbor weight and parent weight are defined to distinguish prediction effect of neighbor coefficients and parent coefficient. For neighbor coefficients, different neighbor weight values are assigned according to their directions and bit-planes. Parent coefficient as a significant coefficient has the same prediction effect on either the current bit-plane or above bit-plane, so it is assigned only one weight value. With classifying the coding coefficients according to neighbor weight and parent weight, and merging the contexts with similar probability distribution, the final context classification scheme fitting for most remote sensing images is acquired. Experimental results have shown that the proposed significance context model is prior to the JPEG2000's. It can employ correlation among wavelet coefficients more sufficiently, and remarkably improve the compression performance.
{"title":"A novel context model for remote sensing image compression","authors":"Qingyuan Wang","doi":"10.1117/12.899567","DOIUrl":"https://doi.org/10.1117/12.899567","url":null,"abstract":"Due to the insufficient employment of the correlation among wavelet coefficients, existing significance coding methods can't reduce entropy redundancy efficiently. In order to solve this problem, a significance context model based on intraband and interband correlation is proposed. The model uses neighbor coefficients in the same subband and a parent coefficient in the lower subband as context to predict the current coding coefficient. Neighbor weight and parent weight are defined to distinguish prediction effect of neighbor coefficients and parent coefficient. For neighbor coefficients, different neighbor weight values are assigned according to their directions and bit-planes. Parent coefficient as a significant coefficient has the same prediction effect on either the current bit-plane or above bit-plane, so it is assigned only one weight value. With classifying the coding coefficients according to neighbor weight and parent weight, and merging the contexts with similar probability distribution, the final context classification scheme fitting for most remote sensing images is acquired. Experimental results have shown that the proposed significance context model is prior to the JPEG2000's. It can employ correlation among wavelet coefficients more sufficiently, and remarkably improve the compression performance.","PeriodicalId":355017,"journal":{"name":"Photoelectronic Detection and Imaging","volume":"194 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115055711","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The camera's motion of detecting and tracking GEOs in spaced-based or ground-based observation platform is very complicated because of the controls of camera's motion for accomplishing the tracking and the motion of platform itself. The controls include: the converts between spontaneous encounter mode and vertical scan mode, detecting and tracking the GEOs with different velocities, etc. The sudden conversion between different modes would make a obvious imaging difference between the two neighbor star-images: stellar shape turn long strip from point, the background's motion is not also uniform linear or constant angular rotation. The imaging difference and irregularity of background's motion enhance the difficulties of star images registration. But the step of registration is necessary in processing of detecting and tracking GEOs based on images sequence. At present almost registration algorithms are designed for some ideal situations or some special conditions needed, thus less of robust to overwhelm the imaging difference and irregularity of background's motion, so most of these are not suitable for automatically detecting and tracking under complicated circumstances in engineering. Another point is that these algorithms are constructed only in image processing level and not consider from astronomy angle. In this paper, an algorithm identifying stars for navigation in astronomy fields is introduced to images registration. For accomplishing to convert camera coordinate to right ascension and declination of sun, there are some parameters should be got in advance, including CCD camera's focal length, field angle and the current camera's axis pointing for building a proper star catalogue. Fortunately to an observation platform, these parameters are known.
{"title":"Algorithm based on star map matching for star images registration","authors":"Xiao-liang Xi, Yong Yu, Xiao-dong Zhou, Jian Zhang","doi":"10.1117/12.900927","DOIUrl":"https://doi.org/10.1117/12.900927","url":null,"abstract":"The camera's motion of detecting and tracking GEOs in spaced-based or ground-based observation platform is very complicated because of the controls of camera's motion for accomplishing the tracking and the motion of platform itself. The controls include: the converts between spontaneous encounter mode and vertical scan mode, detecting and tracking the GEOs with different velocities, etc. The sudden conversion between different modes would make a obvious imaging difference between the two neighbor star-images: stellar shape turn long strip from point, the background's motion is not also uniform linear or constant angular rotation. The imaging difference and irregularity of background's motion enhance the difficulties of star images registration. But the step of registration is necessary in processing of detecting and tracking GEOs based on images sequence. At present almost registration algorithms are designed for some ideal situations or some special conditions needed, thus less of robust to overwhelm the imaging difference and irregularity of background's motion, so most of these are not suitable for automatically detecting and tracking under complicated circumstances in engineering. Another point is that these algorithms are constructed only in image processing level and not consider from astronomy angle. In this paper, an algorithm identifying stars for navigation in astronomy fields is introduced to images registration. For accomplishing to convert camera coordinate to right ascension and declination of sun, there are some parameters should be got in advance, including CCD camera's focal length, field angle and the current camera's axis pointing for building a proper star catalogue. Fortunately to an observation platform, these parameters are known.","PeriodicalId":355017,"journal":{"name":"Photoelectronic Detection and Imaging","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115518737","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A biological sensor based on the resonant transmission characteristics of metal meshes has been proposed in the terahertz (THz) region. We simulated THz transmission characteristics of two kinds of structure by FDTD method: arrays of circular hole and rectangular hole. Their resonant frequencies at the interface of metal and air are 1.42THz and 1.225THz respectively. We find that the refractive index and thickness of the sample commonly affect the surface plasma's resonant frequency. When coupled with a layer of sample of 50 micron on the metallic meshes, the resonance frequency would shift to a lower frequency with an increasing refractive index. Sensitivity of two kinds of structure is 0.64 THz/RIU and 0.507 THz/RIU respectively. The sensitivity differences of two kinds of structure lie mainly in the different dominant resonant transmission mechanism. The thickness also affected detection sensitivity. When thickness of sample is less than the corresponding resonance wavelength, we need to consider the influence of thickness. This theoretical simulation can be good reference for the following experiment.
{"title":"Metallic meshes as biochemistry sensor chip in the terahertz region","authors":"Binbin Li, Jing-ling Shen","doi":"10.1117/12.900162","DOIUrl":"https://doi.org/10.1117/12.900162","url":null,"abstract":"A biological sensor based on the resonant transmission characteristics of metal meshes has been proposed in the terahertz (THz) region. We simulated THz transmission characteristics of two kinds of structure by FDTD method: arrays of circular hole and rectangular hole. Their resonant frequencies at the interface of metal and air are 1.42THz and 1.225THz respectively. We find that the refractive index and thickness of the sample commonly affect the surface plasma's resonant frequency. When coupled with a layer of sample of 50 micron on the metallic meshes, the resonance frequency would shift to a lower frequency with an increasing refractive index. Sensitivity of two kinds of structure is 0.64 THz/RIU and 0.507 THz/RIU respectively. The sensitivity differences of two kinds of structure lie mainly in the different dominant resonant transmission mechanism. The thickness also affected detection sensitivity. When thickness of sample is less than the corresponding resonance wavelength, we need to consider the influence of thickness. This theoretical simulation can be good reference for the following experiment.","PeriodicalId":355017,"journal":{"name":"Photoelectronic Detection and Imaging","volume":"143 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116041638","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Coordinate measuring system which based on the theory of binocular stereo vision is widely used in many areas, whereas their effective measuring ranges are usually not larger than ten meters. In modern times the surveillance of large scale is used more and more in the civil and military area with the development of camera and computer technology. So based on this requirement this paper developed a new measuring model for this binocular stereo vision measuring system which is proper used in outdoor surveillance to get the 3D coordinate of the moving object. When the distance between two cameras is hundreds meters, the installation and camera calibration are quiet simple and convenient without expensive calibration apparatus and an elaborate setup or a planar pattern shown at a few different orientations or complicated camera imaging model and the parameters of math model are easy to get. After building the model of measuring system error analysis is performed to show influence of every parameter on the measuring system error. Both computer simulation and real data have been used to test the validity of our new simple measuring system model.
{"title":"The simple model of large scale co-ordinate measuring system and its error analysis","authors":"Huimin Cai, Wei Zhu, Kejie Li, Meilian Liu","doi":"10.1117/12.900595","DOIUrl":"https://doi.org/10.1117/12.900595","url":null,"abstract":"Coordinate measuring system which based on the theory of binocular stereo vision is widely used in many areas, whereas their effective measuring ranges are usually not larger than ten meters. In modern times the surveillance of large scale is used more and more in the civil and military area with the development of camera and computer technology. So based on this requirement this paper developed a new measuring model for this binocular stereo vision measuring system which is proper used in outdoor surveillance to get the 3D coordinate of the moving object. When the distance between two cameras is hundreds meters, the installation and camera calibration are quiet simple and convenient without expensive calibration apparatus and an elaborate setup or a planar pattern shown at a few different orientations or complicated camera imaging model and the parameters of math model are easy to get. After building the model of measuring system error analysis is performed to show influence of every parameter on the measuring system error. Both computer simulation and real data have been used to test the validity of our new simple measuring system model.","PeriodicalId":355017,"journal":{"name":"Photoelectronic Detection and Imaging","volume":"8194 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129829041","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Xiao-min Liu, Bei Wang, Xu Lu, E. Liang, Guoguang Yang
This paper describes a new concept related to the MEMS(Micro Electro Mechanical system) imaging-array sensors with the structure of micro-cantilever-arrays for detecting far IR and THz radiation. The measure principle is based on an improved optical lever and the core component is a set of micro-displacement measuring device with nano-degree displacement measurement. The amplification coefficient of this improved optical cantilever can reach 102~103 times, combined with a high resolving power to 10-10m. Compared with focal plane arrays sensors, these tape sensors have the ability to measure deformations of micro-cantilever-arrays caused by far IR or THz radiation directly, which can increase the radiation detector sensitivity. The validity of this method is proved by practical experiments. Imaging-array sensors, based on this measure principle, can be made into a new-type MEMS Far IR or THz sensors.
{"title":"Far infrared / Terahertz micromechanical imaging-array sensors based on nano-scale optical measurement technology","authors":"Xiao-min Liu, Bei Wang, Xu Lu, E. Liang, Guoguang Yang","doi":"10.1117/12.900788","DOIUrl":"https://doi.org/10.1117/12.900788","url":null,"abstract":"This paper describes a new concept related to the MEMS(Micro Electro Mechanical system) imaging-array sensors with the structure of micro-cantilever-arrays for detecting far IR and THz radiation. The measure principle is based on an improved optical lever and the core component is a set of micro-displacement measuring device with nano-degree displacement measurement. The amplification coefficient of this improved optical cantilever can reach 102~103 times, combined with a high resolving power to 10-10m. Compared with focal plane arrays sensors, these tape sensors have the ability to measure deformations of micro-cantilever-arrays caused by far IR or THz radiation directly, which can increase the radiation detector sensitivity. The validity of this method is proved by practical experiments. Imaging-array sensors, based on this measure principle, can be made into a new-type MEMS Far IR or THz sensors.","PeriodicalId":355017,"journal":{"name":"Photoelectronic Detection and Imaging","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126675296","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In material classification, distilling eigenvalue will use the object's true gray levels. The problem is objects in a bag almost always overlap with others. Being able to identify the object of interest and remove the overlap effects becomes the key issue that needs to be solved. First, the paper took an n-object-overlapping problem simplified to a two-object-overlapping problem. So the research focus turned to computing true gray levels for two-object-overlapping problem. It was necessary to develop models that can be used to remove the background object overlapping effects. The author took back scatter images for example, discussed the development of the mathematical model for removing the overlapping effects, solved the model parameter by experiment and analyzed model error. This method has been used in x-ray security inspection equipment of DT Inspection equipment limited company. The results of application show that the algorithm is feasible. This is a unique contribution to the explosive detection community.
{"title":"Digital image processing algorithms to determining an object's true gray levels in x-ray back scatter images","authors":"Lina Sun","doi":"10.1117/12.900188","DOIUrl":"https://doi.org/10.1117/12.900188","url":null,"abstract":"In material classification, distilling eigenvalue will use the object's true gray levels. The problem is objects in a bag almost always overlap with others. Being able to identify the object of interest and remove the overlap effects becomes the key issue that needs to be solved. First, the paper took an n-object-overlapping problem simplified to a two-object-overlapping problem. So the research focus turned to computing true gray levels for two-object-overlapping problem. It was necessary to develop models that can be used to remove the background object overlapping effects. The author took back scatter images for example, discussed the development of the mathematical model for removing the overlapping effects, solved the model parameter by experiment and analyzed model error. This method has been used in x-ray security inspection equipment of DT Inspection equipment limited company. The results of application show that the algorithm is feasible. This is a unique contribution to the explosive detection community.","PeriodicalId":355017,"journal":{"name":"Photoelectronic Detection and Imaging","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126803309","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
It is important to retrieve aerosol optical properties over coastal region not only for study of oceanic productivity but also for study of climate because coastal region is highly influenced by neighboring aerosol source regions. The present operational Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol retrieval algorithm works reasonably well over clear ocean areas but fails to give any results over brighter coastal waters. This is because: the turbid waters are not dark for the two aerosol retrieval channels centered near 0.553ìm, 0.646ìm. We have developed an aerosol retrieval algorithm for remote sensing of aerosol properties over turbid coastal water. In this algorithm, channels centered near 0.86,1.24,1.64 and 2.13ìm are used. If necessary, the reflectance of 0.86ìm will be corrected. The proposed algorithm is applicable for MODIS data observed over turbid coastal water in the southeast of China. The retrieval results agree quite well with the measurements obtained with sun photometers, and it can be easily used in the present operational aerosol retrieval algorithm. As a result, many valuable aerosol data can be obtained.
{"title":"A new method for improving the MODIS aerosol retrieval over coastal water","authors":"Jiacheng Wang","doi":"10.1117/12.900580","DOIUrl":"https://doi.org/10.1117/12.900580","url":null,"abstract":"It is important to retrieve aerosol optical properties over coastal region not only for study of oceanic productivity but also for study of climate because coastal region is highly influenced by neighboring aerosol source regions. The present operational Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol retrieval algorithm works reasonably well over clear ocean areas but fails to give any results over brighter coastal waters. This is because: the turbid waters are not dark for the two aerosol retrieval channels centered near 0.553ìm, 0.646ìm. We have developed an aerosol retrieval algorithm for remote sensing of aerosol properties over turbid coastal water. In this algorithm, channels centered near 0.86,1.24,1.64 and 2.13ìm are used. If necessary, the reflectance of 0.86ìm will be corrected. The proposed algorithm is applicable for MODIS data observed over turbid coastal water in the southeast of China. The retrieval results agree quite well with the measurements obtained with sun photometers, and it can be easily used in the present operational aerosol retrieval algorithm. As a result, many valuable aerosol data can be obtained.","PeriodicalId":355017,"journal":{"name":"Photoelectronic Detection and Imaging","volume":"83 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129072477","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We have developed a novel THz detector which uses the cantilever technology and surface plasmon resonance (SPR) technology to achieve a high sensitivity. The Micro Electro Mechanical System (MEMS) technology is adopted to fabricate the detector, which comprise thermo-sensitive bi-material micro-cantilever, prism and optical readout system. The bi-material of Si3N4 and Al is used to fabricate the micro-cantilever because of the good absorption characteristic for THz of Si3N4 and the great difference in thermal expansion coefficient of the bi-material for the deformation of the micro-cantilever. In order to increase the deformation of micro-cantilever, the method of computer simulation is used to obtain the optimal structure of micro-cantilever and the thickness of Si3N4 and Al. The function of the glass prism is to make the incident light generate total reflection under certain conditions. The gold film is sputtering on the top of glass slide using the method of magnetron sputtering and it is necessary for the generation of SPR performance. The optical readout system can make the change of cantilever bending convert to the change of reflection luminous intensity proportionally. The heat on the micro-cantilever coming from the THz radiation can lose easily in the air, so the detector is placed vertically in a cylindrical vacuum chamber which is sealed with quartz glasses and polyethylene lamina at the two end surfaces respectively. The quartz glass is used for the incidence of visible polarized light and the polyethylene lamina for the THz radiation. In order to maintain the vacuum performance of the chamber, the mechanical pump and molecular pump are adopted. In static mode, THz radiation absorption raises the temperature of micro-cantilever, so it bends proportionally. The micro-cantilever bending changes the thicknesses of the gap between the micro-cantilever and the metallic thin film on the micro-prism. It will result in a shift of the SPR angle. Therefore, the surface plasmon excitation efficiency and therewith the measured at a fixed incident angle reflectance of a metallic film will be changed almost proportionally to the cantilever bending. Consequently, the radiation energy of THz can be determined via the metallic film reflectivity change. Finally, the technology of image processing is introduced in detail.
{"title":"A high sensitivity THz detector","authors":"Bo Su, Guoteng Duan","doi":"10.1117/12.900992","DOIUrl":"https://doi.org/10.1117/12.900992","url":null,"abstract":"We have developed a novel THz detector which uses the cantilever technology and surface plasmon resonance (SPR) technology to achieve a high sensitivity. The Micro Electro Mechanical System (MEMS) technology is adopted to fabricate the detector, which comprise thermo-sensitive bi-material micro-cantilever, prism and optical readout system. The bi-material of Si3N4 and Al is used to fabricate the micro-cantilever because of the good absorption characteristic for THz of Si3N4 and the great difference in thermal expansion coefficient of the bi-material for the deformation of the micro-cantilever. In order to increase the deformation of micro-cantilever, the method of computer simulation is used to obtain the optimal structure of micro-cantilever and the thickness of Si3N4 and Al. The function of the glass prism is to make the incident light generate total reflection under certain conditions. The gold film is sputtering on the top of glass slide using the method of magnetron sputtering and it is necessary for the generation of SPR performance. The optical readout system can make the change of cantilever bending convert to the change of reflection luminous intensity proportionally. The heat on the micro-cantilever coming from the THz radiation can lose easily in the air, so the detector is placed vertically in a cylindrical vacuum chamber which is sealed with quartz glasses and polyethylene lamina at the two end surfaces respectively. The quartz glass is used for the incidence of visible polarized light and the polyethylene lamina for the THz radiation. In order to maintain the vacuum performance of the chamber, the mechanical pump and molecular pump are adopted. In static mode, THz radiation absorption raises the temperature of micro-cantilever, so it bends proportionally. The micro-cantilever bending changes the thicknesses of the gap between the micro-cantilever and the metallic thin film on the micro-prism. It will result in a shift of the SPR angle. Therefore, the surface plasmon excitation efficiency and therewith the measured at a fixed incident angle reflectance of a metallic film will be changed almost proportionally to the cantilever bending. Consequently, the radiation energy of THz can be determined via the metallic film reflectivity change. Finally, the technology of image processing is introduced in detail.","PeriodicalId":355017,"journal":{"name":"Photoelectronic Detection and Imaging","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-06-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121609806","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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