2D photonic-crystal structures of Papilio blumei butterfly were constructed and the corresponding reflectance spectra were simulated by finite-difference time-domain (FDTD) method. The structural color of butterfly depends on the thickness of film and the size of air hole. Hence, we can obtain any color by manipulating the parameters of FDTD simulation model.
{"title":"Tunable structural color inspired by Papilio blumei butterfly","authors":"Cheng-chung Lee, Mei-ling Lo","doi":"10.1117/12.2190756","DOIUrl":"https://doi.org/10.1117/12.2190756","url":null,"abstract":"2D photonic-crystal structures of Papilio blumei butterfly were constructed and the corresponding reflectance spectra were simulated by finite-difference time-domain (FDTD) method. The structural color of butterfly depends on the thickness of film and the size of air hole. Hence, we can obtain any color by manipulating the parameters of FDTD simulation model.","PeriodicalId":212434,"journal":{"name":"SPIE Optical Systems Design","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134142788","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}
H. Becker, D. Tonova, M. Sundermann, L. Jensen, M. Gyamfi, D. Ristau, M. Mende
Advanced optical thin film design is the key to increase laser durability significantly: either by optimizing the electric field distribution within the coating, or by multi-index or rugate designs. Both ways may be even combined. The electric field distribution within a thin film stack was optimized to avoid peak intensities in critical layers using refractive index engineering and/or layer thickness grading. Femtosecond laser mirrors and dichroics for 780 nm and 390 nm were designed, realized and characterized. Here we present LIDT measurements of electric field optimized mirrors and dichroics, which are almost a factor of three higher compared to standard coating designs. At 780 nm a LIDT of 1.49 J/cm2 has been achieved and at 390 nm 0.58 J/cm2. With the exception of Al2O3, all investigated coating materials show a proportional dependence of the LIDT with electric field maximum, as expected by theory. For Al2O3 based systems the electrical field penetrates deep into the layer stack, a high number of interfaces are involved and interface effects probably limit the achievable LIDT. A similar effect was observed for rugate designs. To exclude such interface effects from the LIDT measurement, a special AR design was developed, which is practically equal for all high index materials. Here a LIDT above substrate damage threshold of 1.7 J/cm2 was achieved.
{"title":"Advanced femtosecond laser coatings raise damage thresholds","authors":"H. Becker, D. Tonova, M. Sundermann, L. Jensen, M. Gyamfi, D. Ristau, M. Mende","doi":"10.1117/12.2191225","DOIUrl":"https://doi.org/10.1117/12.2191225","url":null,"abstract":"Advanced optical thin film design is the key to increase laser durability significantly: either by optimizing the electric field distribution within the coating, or by multi-index or rugate designs. Both ways may be even combined. The electric field distribution within a thin film stack was optimized to avoid peak intensities in critical layers using refractive index engineering and/or layer thickness grading. Femtosecond laser mirrors and dichroics for 780 nm and 390 nm were designed, realized and characterized. Here we present LIDT measurements of electric field optimized mirrors and dichroics, which are almost a factor of three higher compared to standard coating designs. At 780 nm a LIDT of 1.49 J/cm2 has been achieved and at 390 nm 0.58 J/cm2. With the exception of Al2O3, all investigated coating materials show a proportional dependence of the LIDT with electric field maximum, as expected by theory. For Al2O3 based systems the electrical field penetrates deep into the layer stack, a high number of interfaces are involved and interface effects probably limit the achievable LIDT. A similar effect was observed for rugate designs. To exclude such interface effects from the LIDT measurement, a special AR design was developed, which is practically equal for all high index materials. Here a LIDT above substrate damage threshold of 1.7 J/cm2 was achieved.","PeriodicalId":212434,"journal":{"name":"SPIE Optical Systems Design","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127119683","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}
Compensation of lens-heating effects during the exposure scan in an optical lithographic system requires knowledge of the heating profile in the pupil of the projection lens. A necessary component in the accurate estimation of this profile is the total integrated distribution of light, relying on the squared modulus of the Fourier transform (FT) of the photomask layout for individual process layers. Requiring a layout representation in pixelated image format, the most common approach is to compute the FT numerically via the fast Fourier transform (FFT). However, the file size for a standard 26- mm×33-mm mask with 5-nm pixels is an overwhelming 137 TB in single precision; the data importing process alone, prior to FFT computation, can render this method highly impractical. A more feasible solution is to handle layout data in a highly compact format with vertex locations of mask features (polygons), which correspond to elements in an integrated circuit, as well as pattern symmetries and repetitions (e.g., GDSII format). Provided the polygons can decompose into shapes for which analytical FT expressions are possible, the analytical approach dramatically reduces computation time and alleviates the burden of importing extensive mask data. Algorithms have been developed for importing and interpreting hierarchical layout data and computing the analytical FT on a graphics processing unit (GPU) for rapid parallel processing, not assuming incoherent imaging. Testing was performed on the active layer of a 392- μm×297-μm virtual chip test structure with 43 substructures distributed over six hierarchical levels. The factor of improvement in the analytical versus numerical approach for importing layout data, performing CPU-GPU memory transfers, and executing the FT on a single NVIDIA Tesla K20X GPU was 1.6×104, 4.9×103, and 3.8×103, respectively. Various ideas for algorithm enhancements will be discussed.
在光学光刻系统中，曝光扫描期间透镜加热效应的补偿需要了解投影透镜瞳孔中的加热剖面。准确估计该轮廓的必要组成部分是光的总积分分布，依赖于各个工艺层的掩膜布局的傅里叶变换(FT)的平方模量。由于需要像素化图像格式的布局表示，最常用的方法是通过快速傅里叶变换(FFT)对FT进行数值计算。然而，5纳米像素的标准26- mm×33-mm掩模的文件大小在单精度下是惊人的137 TB;在FFT计算之前，数据导入过程本身会使该方法非常不实用。更可行的解决方案是以高度紧凑的格式处理布局数据，其中包含掩模特征(多边形)的顶点位置，这些顶点位置对应于集成电路中的元素，以及图案对称和重复(例如，GDSII格式)。如果多边形可以分解为可以解析FT表达式的形状，则解析方法可以大大减少计算时间并减轻导入大量掩模数据的负担。已经开发了用于导入和解释分层布局数据以及在图形处理单元(GPU)上计算分析FT的算法，以实现快速并行处理，而不是假设非相干成像。在392- μm×297-μm虚拟芯片测试结构的有源层上进行了测试，该结构具有分布在6个层次上的43个子结构。在导入布局数据、执行CPU-GPU内存传输和在单个NVIDIA Tesla K20X GPU上执行FT方面，分析方法与数值方法的改进因素分别为1.6×104、4.9×103和3.8×103。将讨论算法增强的各种想法。
{"title":"Large-scale analytical Fourier transform of photomask layouts using graphics processing units","authors":"J. A. Sakamoto","doi":"10.1117/12.2192040","DOIUrl":"https://doi.org/10.1117/12.2192040","url":null,"abstract":"Compensation of lens-heating effects during the exposure scan in an optical lithographic system requires knowledge of the heating profile in the pupil of the projection lens. A necessary component in the accurate estimation of this profile is the total integrated distribution of light, relying on the squared modulus of the Fourier transform (FT) of the photomask layout for individual process layers. Requiring a layout representation in pixelated image format, the most common approach is to compute the FT numerically via the fast Fourier transform (FFT). However, the file size for a standard 26- mm×33-mm mask with 5-nm pixels is an overwhelming 137 TB in single precision; the data importing process alone, prior to FFT computation, can render this method highly impractical. A more feasible solution is to handle layout data in a highly compact format with vertex locations of mask features (polygons), which correspond to elements in an integrated circuit, as well as pattern symmetries and repetitions (e.g., GDSII format). Provided the polygons can decompose into shapes for which analytical FT expressions are possible, the analytical approach dramatically reduces computation time and alleviates the burden of importing extensive mask data. Algorithms have been developed for importing and interpreting hierarchical layout data and computing the analytical FT on a graphics processing unit (GPU) for rapid parallel processing, not assuming incoherent imaging. Testing was performed on the active layer of a 392- μm×297-μm virtual chip test structure with 43 substructures distributed over six hierarchical levels. The factor of improvement in the analytical versus numerical approach for importing layout data, performing CPU-GPU memory transfers, and executing the FT on a single NVIDIA Tesla K20X GPU was 1.6×104, 4.9×103, and 3.8×103, respectively. Various ideas for algorithm enhancements will be discussed.","PeriodicalId":212434,"journal":{"name":"SPIE Optical Systems Design","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121561522","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 polishing of high-precision surfaces of optical elements like spheres, aspheres and mirrors requires small polishing tools to achieve rms-surface errors below 2 nm. This can lead to typical mid-spatial frequency surface errors that cannot be considered by standard tolerancing tools anymore but might have a major impact on image performance criteria like wavefront error, distortion or image homogeneity. In this paper we will discuss an analytical approach to describe the effect of mid-spatial frequency surface errors on distortion and image homogeneity. Furthermore we have realized a Zemax user-defined surface allowing us to formulate rings and spokes of different frequencies and amplitudes and therefore giving us a tool to do the tolerancing of mid-spatial frequency errors in Zemax directly. We will present the results especially the dependency on the position of the surface in the optical system as well as the ratio of beam diameter to surface error size.
{"title":"Tolerancing the impact of mid-spatial frequency surface errors of lenses on distortion and image homogeneity","authors":"K. Achilles, K. Uhlendorf, D. Ochse","doi":"10.1117/12.2191261","DOIUrl":"https://doi.org/10.1117/12.2191261","url":null,"abstract":"The polishing of high-precision surfaces of optical elements like spheres, aspheres and mirrors requires small polishing tools to achieve rms-surface errors below 2 nm. This can lead to typical mid-spatial frequency surface errors that cannot be considered by standard tolerancing tools anymore but might have a major impact on image performance criteria like wavefront error, distortion or image homogeneity. In this paper we will discuss an analytical approach to describe the effect of mid-spatial frequency surface errors on distortion and image homogeneity. Furthermore we have realized a Zemax user-defined surface allowing us to formulate rings and spokes of different frequencies and amplitudes and therefore giving us a tool to do the tolerancing of mid-spatial frequency errors in Zemax directly. We will present the results especially the dependency on the position of the surface in the optical system as well as the ratio of beam diameter to surface error size.","PeriodicalId":212434,"journal":{"name":"SPIE Optical Systems Design","volume":"9626 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129672690","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}
All the star trackers must be composed of a baffle system to removes stray lights intensity. The baffle is designed to mount in front of the optical system. The performance of a star tracker is often limited by the stray light level on the detector. According to the space conditions, the baffle may deflect due to the temperature variation during the mission. Sun heat flux imposed to the baffle from one side and heat radiates from baffle to the space in all sides. In our case, the baffle is fixed to the satellite structure by four titanium screw. A finite element model has been used to modeling the baffle and temperature distribution and deflection is obtained in worst cold and hot conditions. Results show that in the worst cold condition, baffle is deflected symmetrically whereas in hot case, deflection is not symmetric and the side exposed to the sun light is elongated. Using ray tracing methods along with Monte Carlo algorithm, the baffle efficiency is obtained and compared for both cases. Results show that baffle deflections are not so extreme to force us to cover it with the MLI.
{"title":"Effects of temperature variations on the performance of a space imaging system baffle","authors":"J. Haghshenas, Behzad Mohasel Afshari","doi":"10.1117/12.2191496","DOIUrl":"https://doi.org/10.1117/12.2191496","url":null,"abstract":"All the star trackers must be composed of a baffle system to removes stray lights intensity. The baffle is designed to mount in front of the optical system. The performance of a star tracker is often limited by the stray light level on the detector. According to the space conditions, the baffle may deflect due to the temperature variation during the mission. Sun heat flux imposed to the baffle from one side and heat radiates from baffle to the space in all sides. In our case, the baffle is fixed to the satellite structure by four titanium screw. A finite element model has been used to modeling the baffle and temperature distribution and deflection is obtained in worst cold and hot conditions. Results show that in the worst cold condition, baffle is deflected symmetrically whereas in hot case, deflection is not symmetric and the side exposed to the sun light is elongated. Using ray tracing methods along with Monte Carlo algorithm, the baffle efficiency is obtained and compared for both cases. Results show that baffle deflections are not so extreme to force us to cover it with the MLI.","PeriodicalId":212434,"journal":{"name":"SPIE Optical Systems Design","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115059705","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}
Janos C. Keresztes, R. J. Koshel, R. Chipman, J. Stover, W. Saeys
Common illumination systems in short wave infrared (SWIR) hyperspectral imaging (HSI) include direct or indirect tungsten halogen lights. While direct lights provide more radiation onto the samples than dome setups, thus being more energy efficient, the acquired images often suffer from specular reflections and gloss. Glare artifacts in images increase variability in the data limiting the accuracy of machine vision algorithms for defect detection and quality inspection, or even providing false positives. Although domes are known to provide a near Lambertian illumination and glare free images, glossy regions and heterogeneities may remain in the data in practice. More particularly, in the field of fruit and vegetable quality inspection, due to their waxy surface, it remains challenging to design an efficient realistic lighting system. This paper suggests a new approach to optimize the illumination of fruit and vegetables based on measurements of the bidirectional reflectance distribution function (BRDF), shape and Stokes parameters. From these measured values, a BRDF model is loaded into ray-tracing software for realistic illumination engineering in order to determine the most suitable illumination scheme. This concept is applied to apples and a cross polarizer (CP) with freeform optics (FO) optical configuration is proposed, which allows the FO to be optimized to maximize uniformity in the field of view of the imager and removes the parallel polarized gloss on the apples. The performance of this CP illumination system was determined experimentally for a set of apples. This cross polarized (CP) illumination system provided a uniformity (U) of 92% and an efficiency (ν) of 90%, while U = 87% and ν = 14% for an ideal dome configuration when illuminating a rectangular target. The simulated imaged apples with assigned optical properties performed better with CP (U=80%) than when using a dome (U=73%) by 7%. Finally, the sensitivity of the design for the light positioning and spectral tolerance are investigated.
{"title":"A cross-polarized freeform illumination design for glare reduction in fruit quality inspection","authors":"Janos C. Keresztes, R. J. Koshel, R. Chipman, J. Stover, W. Saeys","doi":"10.1117/12.2193858","DOIUrl":"https://doi.org/10.1117/12.2193858","url":null,"abstract":"Common illumination systems in short wave infrared (SWIR) hyperspectral imaging (HSI) include direct or indirect tungsten halogen lights. While direct lights provide more radiation onto the samples than dome setups, thus being more energy efficient, the acquired images often suffer from specular reflections and gloss. Glare artifacts in images increase variability in the data limiting the accuracy of machine vision algorithms for defect detection and quality inspection, or even providing false positives. Although domes are known to provide a near Lambertian illumination and glare free images, glossy regions and heterogeneities may remain in the data in practice. More particularly, in the field of fruit and vegetable quality inspection, due to their waxy surface, it remains challenging to design an efficient realistic lighting system. This paper suggests a new approach to optimize the illumination of fruit and vegetables based on measurements of the bidirectional reflectance distribution function (BRDF), shape and Stokes parameters. From these measured values, a BRDF model is loaded into ray-tracing software for realistic illumination engineering in order to determine the most suitable illumination scheme. This concept is applied to apples and a cross polarizer (CP) with freeform optics (FO) optical configuration is proposed, which allows the FO to be optimized to maximize uniformity in the field of view of the imager and removes the parallel polarized gloss on the apples. The performance of this CP illumination system was determined experimentally for a set of apples. This cross polarized (CP) illumination system provided a uniformity (U) of 92% and an efficiency (ν) of 90%, while U = 87% and ν = 14% for an ideal dome configuration when illuminating a rectangular target. The simulated imaged apples with assigned optical properties performed better with CP (U=80%) than when using a dome (U=73%) by 7%. Finally, the sensitivity of the design for the light positioning and spectral tolerance are investigated.","PeriodicalId":212434,"journal":{"name":"SPIE Optical Systems Design","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115018544","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}
Y. Tokuta, K. Okita, K. Okuda, T. Kitayama, M. Nakano, S. Nakatani, R. Kudo, K. Yamamura, K. Endo
Aspherical optical elements with high accuracy are important in several fields such as third-generation synchrotron radiation and extreme-ultraviolet lithography. Then the demand of measurement method for aspherical or free-form surface with nanometer resolution is rising. Our purpose is to develop a non-contact profiler to measure free-form surfaces directly with repeatability of figure error of less than 1 nm PV. To achieve this purpose we have developed three-dimensional Nanoprofiler which traces normal vectors of sample surface. The measurement principle is based on the straightness of LASER light and the accuracy of a rotational goniometer. This machine consists of four rotational stages, one translational stage and optical head which has the quadrant photodiode (QPD) and LASER head at optically equal position. In this measurement method, we conform the incident light beam to reflect the beam by controlling five stages and determine the normal vectors and the coordinates of the surface from signal of goniometers, translational stage and QPD. We can obtain three-dimensional figure from the normal vectors and the coordinates by a reconstruction algorithm. To evaluate performance of this machine we measure a concave aspherical mirror ten times. From ten results we calculate measurement repeatability, and we evaluate measurement uncertainty to compare the result with that measured by an interferometer. In consequence, the repeatability of measurement was 2.90 nm (σ) and the difference between the two profiles was ±20 nm. We conclude that the two profiles was correspondent considering systematic errors of each machine.
{"title":"The measurement of an aspherical mirror by three-dimensional nanoprofiler","authors":"Y. Tokuta, K. Okita, K. Okuda, T. Kitayama, M. Nakano, S. Nakatani, R. Kudo, K. Yamamura, K. Endo","doi":"10.1117/12.2191040","DOIUrl":"https://doi.org/10.1117/12.2191040","url":null,"abstract":"Aspherical optical elements with high accuracy are important in several fields such as third-generation synchrotron radiation and extreme-ultraviolet lithography. Then the demand of measurement method for aspherical or free-form surface with nanometer resolution is rising. Our purpose is to develop a non-contact profiler to measure free-form surfaces directly with repeatability of figure error of less than 1 nm PV. To achieve this purpose we have developed three-dimensional Nanoprofiler which traces normal vectors of sample surface. The measurement principle is based on the straightness of LASER light and the accuracy of a rotational goniometer. This machine consists of four rotational stages, one translational stage and optical head which has the quadrant photodiode (QPD) and LASER head at optically equal position. In this measurement method, we conform the incident light beam to reflect the beam by controlling five stages and determine the normal vectors and the coordinates of the surface from signal of goniometers, translational stage and QPD. We can obtain three-dimensional figure from the normal vectors and the coordinates by a reconstruction algorithm. To evaluate performance of this machine we measure a concave aspherical mirror ten times. From ten results we calculate measurement repeatability, and we evaluate measurement uncertainty to compare the result with that measured by an interferometer. In consequence, the repeatability of measurement was 2.90 nm (σ) and the difference between the two profiles was ±20 nm. We conclude that the two profiles was correspondent considering systematic errors of each machine.","PeriodicalId":212434,"journal":{"name":"SPIE Optical Systems Design","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115329080","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}
Zernike polynomial surface and wavefront descriptions have been used in the manufacture of projection optics for microlithography since the 1970’s. This is because the optical tolerances are so small that one cannot rely on trial-anderror to achieve diffraction-limited wavefront correction. No manufactured optical surface can be considered to be spherical or even rotationally symmetrical; they have to be measured and systematically compensated. Over the last few decades of Moore’s Law there have been continuing decreases in wavefront tolerances and a consequent increase in sophistication of deterministic optical polishing and compensation strategies for residual surface and alignment errors. Optical designs have evolved from all-spherical to the inclusion of rotationally symmetric aspheric surfaces, more recently in the form of Forbes Q-type polynomials, to Zernike polynomials that include bilaterally symmetric terms. These historical trends and their application to EUV projection optics are reviewed and illustrated with two recent optical designs.
{"title":"Frits Zernike and microlithography","authors":"D. M. Williamson","doi":"10.1117/12.2191129","DOIUrl":"https://doi.org/10.1117/12.2191129","url":null,"abstract":"Zernike polynomial surface and wavefront descriptions have been used in the manufacture of projection optics for microlithography since the 1970’s. This is because the optical tolerances are so small that one cannot rely on trial-anderror to achieve diffraction-limited wavefront correction. No manufactured optical surface can be considered to be spherical or even rotationally symmetrical; they have to be measured and systematically compensated. Over the last few decades of Moore’s Law there have been continuing decreases in wavefront tolerances and a consequent increase in sophistication of deterministic optical polishing and compensation strategies for residual surface and alignment errors. Optical designs have evolved from all-spherical to the inclusion of rotationally symmetric aspheric surfaces, more recently in the form of Forbes Q-type polynomials, to Zernike polynomials that include bilaterally symmetric terms. These historical trends and their application to EUV projection optics are reviewed and illustrated with two recent optical designs.","PeriodicalId":212434,"journal":{"name":"SPIE Optical Systems Design","volume":"9 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114395691","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}
B. Gür, G. Otter, R. Jansen, J. Groote-Schaarsberg, S. Brinkers
Optical components with scattering properties, so-called diffusers, are core elements of calibration units in earth observation instruments. Their performance influences significantly the achievable accuracy of scientific observations. It is of high importance however to characterize the scattering properties of such a diffuser with minimum uncertainty on-ground before launched into orbit and before being utilized in its calibration purpose. Over the past decades TNO has operated an “Absolute Radiometric Calibration Facility (ARCF)” to ensure such accurate characterization of space components. In the recent past TNO has put increased efforts in upgrading and modernizing its facility into a modern high class facility (ARCF 2.0) to measure scattering properties of a variety of materials and components to meet the growing demands for accurate measurements for space applications. This paper describes the above mentioned facility ARCF 2.0 with its unique measurement capabilities and outlies several examples.
{"title":"The absolute radiometric calibration facility ARCF 2.0 at TNO","authors":"B. Gür, G. Otter, R. Jansen, J. Groote-Schaarsberg, S. Brinkers","doi":"10.1117/12.2191595","DOIUrl":"https://doi.org/10.1117/12.2191595","url":null,"abstract":"Optical components with scattering properties, so-called diffusers, are core elements of calibration units in earth observation instruments. Their performance influences significantly the achievable accuracy of scientific observations. It is of high importance however to characterize the scattering properties of such a diffuser with minimum uncertainty on-ground before launched into orbit and before being utilized in its calibration purpose. Over the past decades TNO has operated an “Absolute Radiometric Calibration Facility (ARCF)” to ensure such accurate characterization of space components. In the recent past TNO has put increased efforts in upgrading and modernizing its facility into a modern high class facility (ARCF 2.0) to measure scattering properties of a variety of materials and components to meet the growing demands for accurate measurements for space applications. This paper describes the above mentioned facility ARCF 2.0 with its unique measurement capabilities and outlies several examples.","PeriodicalId":212434,"journal":{"name":"SPIE Optical Systems Design","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130935366","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}
J. Hartung, M. Beier, T. Peschel, A. Gebhardt, S. Risse
For optical systems consisting of metal (in general freeform) mirrors there exist several diamond turning fabrication approaches. These are distuingished by the effort in manufacturing and integration of the later system. The more work one puts into the manufacturing stage the less complicated is the alignment and integration afterwards. For example the most degrees of freedom have to be aligned in integration phase if every mirror of the system is fabricated as a single optical component. For a three mirror anastigmat with three freeform mirrors the degrees of freedom sum up to 18. Therefore the mirror fabrication itself is more or less easy, but the integration is very difficult. There are three major parts in the design and manufacturing process chain to be considered for tackling this integration problem. At the first position in the process chain there is the optical design occuring. At this stage a negotiation between manufacturing and design could improve manufacturability because of more possible integration approaches. The second stage is the mechanical design. Here the appropriate manufacturing approach is already chosen, but may be revisited due to incompatiblities with, e.g., stress specifications. The third level is the manufacturing stage. Here are different clamping approaches and fabrication methods possible. The current article will focus on an approach ("snap-together") where two mirrors are fabricated on one substrate and therefore a reduction of the number of degrees of freedom to be aligned are reduced to six. This improves the amount of time needed for the system integration significantly in contrast to a single mirror fabrication.
{"title":"Mechanical design implementation and mathematical considerations for ultra precise diamond turning of multiple freeform mirrors on a common substrate","authors":"J. Hartung, M. Beier, T. Peschel, A. Gebhardt, S. Risse","doi":"10.1117/12.2191043","DOIUrl":"https://doi.org/10.1117/12.2191043","url":null,"abstract":"For optical systems consisting of metal (in general freeform) mirrors there exist several diamond turning fabrication approaches. These are distuingished by the effort in manufacturing and integration of the later system. The more work one puts into the manufacturing stage the less complicated is the alignment and integration afterwards. For example the most degrees of freedom have to be aligned in integration phase if every mirror of the system is fabricated as a single optical component. For a three mirror anastigmat with three freeform mirrors the degrees of freedom sum up to 18. Therefore the mirror fabrication itself is more or less easy, but the integration is very difficult. There are three major parts in the design and manufacturing process chain to be considered for tackling this integration problem. At the first position in the process chain there is the optical design occuring. At this stage a negotiation between manufacturing and design could improve manufacturability because of more possible integration approaches. The second stage is the mechanical design. Here the appropriate manufacturing approach is already chosen, but may be revisited due to incompatiblities with, e.g., stress specifications. The third level is the manufacturing stage. Here are different clamping approaches and fabrication methods possible. The current article will focus on an approach (\"snap-together\") where two mirrors are fabricated on one substrate and therefore a reduction of the number of degrees of freedom to be aligned are reduced to six. This improves the amount of time needed for the system integration significantly in contrast to a single mirror fabrication.","PeriodicalId":212434,"journal":{"name":"SPIE Optical Systems Design","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131192190","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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