J. Schmitt, C. Bischoff, U. Rädel, M. Grau, U. Wallrabe, F. Völklein
Shaping of laser light intensities by using Diffractive Optical Elements allows the adaption of the incident light to its application. Fused silica is used where for example UV-light or high temperatures are mandatory. For high diffraction efficiency the quality of the etched surface areas is important. The investigation of different process parameters for Ion Beam and Reactive Ion Etching reveals that only Ion Beam Etching provides surfaces with optical quality. Measurements of the influence of the surface quality on the diffraction efficiencies prove that the surfaces generated by Reactive Ion Etching are not suitable. Due to the high selectivity of the process Reactive Ion Etching is nevertheless a reasonable choice for the fabrication of Diffractive Optical Elements. To improve the quality of the etched surfaces a post processing with Ion Beam Etching is developed. Simulations in MATLAB display that the angle dependent removal of the surface during the Ion Beam Etching causes a smoothing of the surface roughness. The positive influence of a post processing on the diffraction efficiency is outlined by measurements. The ion beam post processing leads to an increase of the etching depth. For the fabrication of high efficient Diffractive Optical Elements this has to be taken into account. The relation is investigated and transferred to the fabrication of four-level gratings. Diffraction efficiencies up to 78 % instead of the ideal 81 % underline the practicability of the developed post processing.
{"title":"Enhancement of RIE: etched Diffractive Optical Elements surfaces by using Ion Beam Etching","authors":"J. Schmitt, C. Bischoff, U. Rädel, M. Grau, U. Wallrabe, F. Völklein","doi":"10.1117/12.2191053","DOIUrl":"https://doi.org/10.1117/12.2191053","url":null,"abstract":"Shaping of laser light intensities by using Diffractive Optical Elements allows the adaption of the incident light to its application. Fused silica is used where for example UV-light or high temperatures are mandatory. For high diffraction efficiency the quality of the etched surface areas is important. The investigation of different process parameters for Ion Beam and Reactive Ion Etching reveals that only Ion Beam Etching provides surfaces with optical quality. Measurements of the influence of the surface quality on the diffraction efficiencies prove that the surfaces generated by Reactive Ion Etching are not suitable. Due to the high selectivity of the process Reactive Ion Etching is nevertheless a reasonable choice for the fabrication of Diffractive Optical Elements. To improve the quality of the etched surfaces a post processing with Ion Beam Etching is developed. Simulations in MATLAB display that the angle dependent removal of the surface during the Ion Beam Etching causes a smoothing of the surface roughness. The positive influence of a post processing on the diffraction efficiency is outlined by measurements. The ion beam post processing leads to an increase of the etching depth. For the fabrication of high efficient Diffractive Optical Elements this has to be taken into account. The relation is investigated and transferred to the fabrication of four-level gratings. Diffraction efficiencies up to 78 % instead of the ideal 81 % underline the practicability of the developed post processing.","PeriodicalId":212434,"journal":{"name":"SPIE Optical Systems Design","volume":"13 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":"127660810","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. Gómez-Pedrero, Diego Rodríguez-Ibáñez, J. Alonso, Juan A. Quirgoa
With the advent of techniques devised for the mass production of optical components made with surfaces of arbitrary form (also known as free form surfaces) in the last years, a parallel development of measuring systems adapted for these new kind of surfaces constitutes a real necessity for the industry. Profilometry is one of the preferred methods for the assessment of the quality of a surface, and is widely employed in the optical fabrication industry for the quality control of its products. In this work, we present the design, development and assembly of a new profilometer with five axis of movement, specifically suited to the measurement of medium size (up to 150 mm of diameter) "free-form" optical surfaces with sub-micrometer accuracy and low measuring times. The apparatus is formed by three X, Y, Z linear motorized positioners plus and additional angular and a tilt positioner employed to locate accurately the surface to be measured and the probe which can be a mechanical or an optical one, being optical one a confocal sensor based on chromatic aberration. Both optical and mechanical probes guarantee an accuracy lower than the micrometer in the determination of the surface height, thus ensuring an accuracy in the surface curvatures of the order of 0.01 D or better. An original calibration procedure based on the measurement of a precision sphere has been developed in order to correct the perpendicularity error between the axes of the linear positioners. To reduce the measuring time of the profilometer, a custom electronics, based on an Arduino™ controller, have been designed and produced in order to synchronize the five motorized positioners and the optical and mechanical probes so that a medium size surface (around 10 cm of diameter) with a dynamic range in curvatures of around 10 D, can be measured in less than 300 seconds (using three axes) keeping the resolution in height and curvature in the figures mentioned above.
随着近年来为任意形状表面(也称为自由形状表面)制造的光学元件的大规模生产而设计的技术的出现，适用于这些新型表面的测量系统的平行发展构成了该行业的真正必要性。轮廓测量法是评估表面质量的首选方法之一，在光学制造行业中被广泛应用于产品的质量控制。在这项工作中，我们介绍了一种具有五轴运动的新型轮廓仪的设计，开发和组装，特别适合于测量中等尺寸(直径高达150毫米)。具有亚微米精度和低测量时间的“自由形状”光学表面。该装置由三个X, Y, Z直线电动定位器和附加的角度定位器和倾斜定位器组成，用于精确定位待测表面，探头可以是机械探头或光学探头，光学探头是基于色差的共聚焦传感器。光学和机械探头在确定表面高度时保证精度低于微米，从而确保表面曲率精度为0.01 D或更好。为了校正直线定位机轴线之间的垂直度误差，提出了一种基于精密球体测量的原始校准方法。为了减少轮廓仪的测量时间，基于Arduino™控制器的定制电子设备已经设计和生产，以便同步五个电动定位器和光学和机械探头，以便在不到300秒的时间内测量一个中等尺寸的表面(直径约10厘米)，动态范围在10 D左右(使用三个轴)，保持高度和曲率的分辨率在上面提到的数字。
{"title":"Design and development of a profilometer for the fast and accurate characterization of optical surfaces","authors":"J. Gómez-Pedrero, Diego Rodríguez-Ibáñez, J. Alonso, Juan A. Quirgoa","doi":"10.1117/12.2191058","DOIUrl":"https://doi.org/10.1117/12.2191058","url":null,"abstract":"With the advent of techniques devised for the mass production of optical components made with surfaces of arbitrary form (also known as free form surfaces) in the last years, a parallel development of measuring systems adapted for these new kind of surfaces constitutes a real necessity for the industry. Profilometry is one of the preferred methods for the assessment of the quality of a surface, and is widely employed in the optical fabrication industry for the quality control of its products. In this work, we present the design, development and assembly of a new profilometer with five axis of movement, specifically suited to the measurement of medium size (up to 150 mm of diameter) \"free-form\" optical surfaces with sub-micrometer accuracy and low measuring times. The apparatus is formed by three X, Y, Z linear motorized positioners plus and additional angular and a tilt positioner employed to locate accurately the surface to be measured and the probe which can be a mechanical or an optical one, being optical one a confocal sensor based on chromatic aberration. Both optical and mechanical probes guarantee an accuracy lower than the micrometer in the determination of the surface height, thus ensuring an accuracy in the surface curvatures of the order of 0.01 D or better. An original calibration procedure based on the measurement of a precision sphere has been developed in order to correct the perpendicularity error between the axes of the linear positioners. To reduce the measuring time of the profilometer, a custom electronics, based on an Arduino™ controller, have been designed and produced in order to synchronize the five motorized positioners and the optical and mechanical probes so that a medium size surface (around 10 cm of diameter) with a dynamic range in curvatures of around 10 D, can be measured in less than 300 seconds (using three axes) keeping the resolution in height and curvature in the figures mentioned above.","PeriodicalId":212434,"journal":{"name":"SPIE Optical Systems Design","volume":"23 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":"127499476","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}
Development of antireflective coatings realized by thin film systems requires their characterization and optimization of their properties. Functional properties of such interference devices are determined by optical constants and thicknesses of the individual films and various defects taking place in these systems. In optics industry the characterization of the films is mostly performed in a relatively narrow spectral range using simple dispersion models and, moreover, the defects are not taken into account at all. This manner of characterization fails if applied to real-world non-ideal thin film systems because the measured data do not contain sufficient information about all the parameters describing the system including imperfections. Reliable characterization requires the following changes: extension of spectral range of measurements, combination of spectrophotometry and ellipsometry, utilization of physically correct dispersion models (Kramers-Kronig consistency, sum rules), inclusion of structural defects instrument imperfection into the models and simultaneous processing of all experimental data. This enables us to remove or reduce a correlation among the parameters searched so that correct and sufficiently precise determination of parameter values is achieved. Since the presence and properties of the defects are difficult to control independently by tuning of the deposition conditions, the optimization does not in general involve the elimination of defects. Instead they are taken into account in the design of the film systems. The outlined approach is demonstrated on the characterization and optimization of ultraviolet antireflective coating formed by double layer of Al2O3 and MgF2 deposited on fused silica.
{"title":"Wide spectral range characterization of antireflective coatings and their optimization","authors":"D. Franta, D. Nečas, I. Ohlídal, J. Jankuj","doi":"10.1117/12.2190109","DOIUrl":"https://doi.org/10.1117/12.2190109","url":null,"abstract":"Development of antireflective coatings realized by thin film systems requires their characterization and optimization of their properties. Functional properties of such interference devices are determined by optical constants and thicknesses of the individual films and various defects taking place in these systems. In optics industry the characterization of the films is mostly performed in a relatively narrow spectral range using simple dispersion models and, moreover, the defects are not taken into account at all. This manner of characterization fails if applied to real-world non-ideal thin film systems because the measured data do not contain sufficient information about all the parameters describing the system including imperfections. Reliable characterization requires the following changes: extension of spectral range of measurements, combination of spectrophotometry and ellipsometry, utilization of physically correct dispersion models (Kramers-Kronig consistency, sum rules), inclusion of structural defects instrument imperfection into the models and simultaneous processing of all experimental data. This enables us to remove or reduce a correlation among the parameters searched so that correct and sufficiently precise determination of parameter values is achieved. Since the presence and properties of the defects are difficult to control independently by tuning of the deposition conditions, the optimization does not in general involve the elimination of defects. Instead they are taken into account in the design of the film systems. The outlined approach is demonstrated on the characterization and optimization of ultraviolet antireflective coating formed by double layer of Al2O3 and MgF2 deposited on fused silica.","PeriodicalId":212434,"journal":{"name":"SPIE Optical Systems Design","volume":"33 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":"124668920","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. L. Pearson, Gareth W. Roberts, P. Rees, S. Thompson
The use of autocollimator-based profilometers of the Nanometer Optical measuring Machine (NOM) design has been reported for the evaluation of X-ray optics for some time. We report a related development in the use of a non-contact NOM profilometer for the in situ measurement of base radius of curvature and conic constant for E-ELT primary mirror segments during fabrication. The instrument is unusual in NOM design in that it is deployable onto a CNC polishing machine in an industrial fabrication environment. Whilst the measurement of radius of curvature of spherical surfaces over a single scan has been reported previously, here we report on the use of this instrument to measure optical surfaces with an aspheric departure of 180 micrometers using a grid of multiple scans and bespoke surface fitting software. The repeatability of the measurement has been found to be approximately 1 mm in a measured radius of curvature of approximately 90 m. The absolute accuracy is limited by the accuracy of the calibration of the autocollimator and the in situ calibration of the instrument during operation.
{"title":"Use of a NOM profilometer to measure large aspheric surfaces","authors":"J. L. Pearson, Gareth W. Roberts, P. Rees, S. Thompson","doi":"10.1117/12.2191322","DOIUrl":"https://doi.org/10.1117/12.2191322","url":null,"abstract":"The use of autocollimator-based profilometers of the Nanometer Optical measuring Machine (NOM) design has been reported for the evaluation of X-ray optics for some time. We report a related development in the use of a non-contact NOM profilometer for the in situ measurement of base radius of curvature and conic constant for E-ELT primary mirror segments during fabrication. The instrument is unusual in NOM design in that it is deployable onto a CNC polishing machine in an industrial fabrication environment. Whilst the measurement of radius of curvature of spherical surfaces over a single scan has been reported previously, here we report on the use of this instrument to measure optical surfaces with an aspheric departure of 180 micrometers using a grid of multiple scans and bespoke surface fitting software. The repeatability of the measurement has been found to be approximately 1 mm in a measured radius of curvature of approximately 90 m. The absolute accuracy is limited by the accuracy of the calibration of the autocollimator and the in situ calibration of the instrument during operation.","PeriodicalId":212434,"journal":{"name":"SPIE Optical Systems Design","volume":"53 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":"115305821","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}
G. Dubroca, M. Richert, Didier Loiseaux, J. Caron, J. Bézy
To increase the accuracy of earth-observation spectro-imagers, it is necessary to achieve high levels of depolarization of the incoming beam. The preferred device in space instrument is the so-called polarization scrambler. It is made of birefringent crystal wedges arranged in a single or dual Babinet. Today, with required radiometric accuracies of the order of 0.1%, it is necessary to develop tools to find optimal and low sensitivity solutions quickly and to measure the performances with a high level of accuracy.
{"title":"Recent developments in the design and verification of crystalline polarization scramblers for space applications","authors":"G. Dubroca, M. Richert, Didier Loiseaux, J. Caron, J. Bézy","doi":"10.1117/12.2191226","DOIUrl":"https://doi.org/10.1117/12.2191226","url":null,"abstract":"To increase the accuracy of earth-observation spectro-imagers, it is necessary to achieve high levels of depolarization of the incoming beam. The preferred device in space instrument is the so-called polarization scrambler. It is made of birefringent crystal wedges arranged in a single or dual Babinet. Today, with required radiometric accuracies of the order of 0.1%, it is necessary to develop tools to find optimal and low sensitivity solutions quickly and to measure the performances with a high level of accuracy.","PeriodicalId":212434,"journal":{"name":"SPIE Optical Systems Design","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115227937","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}
Infrared optical systems are widely used for surveillance, military and many other purposes. Image quality of such systems should be stable over wide working temperature range from – 40 up to +60°C. Due to temperature dependence of properties of optical materials and mechanical parts it is a difficult task to achieve the required stability. Passive and active methods exist to compensate the most significant aberration – so called thermal defocus. Passive compensation ways are the most attractive because complicated mechanical parts or devices are not required. The work is aimed at developing and improving of the IR system design methods. The analysis of thermoaberrations starts with analysis of possibilities of chromatic and thermal defocus correction in two and three component systems. Based on these results the development and improvement of the design method which was proposed earlier was implemented. Examples of designed systems are given. Results of the work may be helpful for designers to find optimal material combination for further designing of thermostabilized systems working in IR region.
{"title":"Research of aberration properties and passive athermalization of optical systems for infrared region","authors":"G. Romanova, Grzegorz Pyś","doi":"10.1117/12.2191119","DOIUrl":"https://doi.org/10.1117/12.2191119","url":null,"abstract":"Infrared optical systems are widely used for surveillance, military and many other purposes. Image quality of such systems should be stable over wide working temperature range from – 40 up to +60°C. Due to temperature dependence of properties of optical materials and mechanical parts it is a difficult task to achieve the required stability. Passive and active methods exist to compensate the most significant aberration – so called thermal defocus. Passive compensation ways are the most attractive because complicated mechanical parts or devices are not required. The work is aimed at developing and improving of the IR system design methods. The analysis of thermoaberrations starts with analysis of possibilities of chromatic and thermal defocus correction in two and three component systems. Based on these results the development and improvement of the design method which was proposed earlier was implemented. Examples of designed systems are given. Results of the work may be helpful for designers to find optimal material combination for further designing of thermostabilized systems working in IR region.","PeriodicalId":212434,"journal":{"name":"SPIE Optical Systems Design","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121087217","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}
Thermal management in solid state laser is a challenge to the high power laser industry’s ability to provide continued improvements in device and system performance. In this work an investigation of heat generation and thermo-mechanical effect in a high-power Nd:YAG and Yb:YAG cylindrical-type solid state laser pumped longitudinally with different power by fibre coupled laser diode is carried out by numerical simulation based on the finite element method (FEM). Impact of the dopant concentration on the power conversion efficiency is included in the simulation. The distribution of the temperature inside the lasing material is resolute according to the thermal conductivity. The thermo-mechanical effect is explored as a function of pump power in order to determine the maximum pumping power allowed to prevent the crystal’s fracture. The presented simulations are in broad agreement with analytical solutions; provided that the boundary condition of the pump induced heat generation is accurately modelled.
{"title":"Heat generation and thermo-mechanical effect modeling in longitudinally diode-pumped solid state lasers","authors":"F. Lakhdari, Ismahen Osmani, S. Tabet","doi":"10.1117/12.2191158","DOIUrl":"https://doi.org/10.1117/12.2191158","url":null,"abstract":"Thermal management in solid state laser is a challenge to the high power laser industry’s ability to provide continued improvements in device and system performance. In this work an investigation of heat generation and thermo-mechanical effect in a high-power Nd:YAG and Yb:YAG cylindrical-type solid state laser pumped longitudinally with different power by fibre coupled laser diode is carried out by numerical simulation based on the finite element method (FEM). Impact of the dopant concentration on the power conversion efficiency is included in the simulation. The distribution of the temperature inside the lasing material is resolute according to the thermal conductivity. The thermo-mechanical effect is explored as a function of pump power in order to determine the maximum pumping power allowed to prevent the crystal’s fracture. The presented simulations are in broad agreement with analytical solutions; provided that the boundary condition of the pump induced heat generation is accurately modelled.","PeriodicalId":212434,"journal":{"name":"SPIE Optical Systems Design","volume":"18 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127436211","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}
G. Lousberg, V. Moreau, J. Schumacher, M. Piérard, Aude Somja, P. Gloesener, C. Flebus
AMOS has developed a hybrid active optics system that combines hydraulic and pneumatic properties of actuators to support a 4-m primary mirror. The mirror is intended to be used in the Daniel K. Inouye Solar Telescope (DKIST, formerly the Advanced Technology Solar Telescope) that will be installed by the National Solar Observatory (NSO) atop the Haleakala volcano in Hawaii. The mirror support design is driven by the needs of (1) minimizing the support-induced mirror distortions under telescope operating conditions, (2) shaping the mirror surface to the desired profile, and (3) providing a high stiffness against wind loads. In order to fulfill these requirements, AMOS proposes an innovative support design that consist of 118 axial actuators and 24 lateral actuators. The axial support is based on coupled hydraulic and pneumatic actuators. The hydraulic part is a passive system whose main function is to support the mirror weight with a high stiffness. The pneumatic part is actively controlled so as to compensate for low-order wavefront aberrations that are generated by the mirror support itself or by any other elements in the telescope optical chain. The performances of the support and its adequacy with the requirements are assessed with the help of a comprehensive analysis loop involving finite-element, thermal and optical modellings.
AMOS开发了一种混合主动光学系统，该系统结合了执行器的液压和气动特性来支持一个4米的主镜。该镜面将用于Daniel K. Inouye太阳望远镜(DKIST，前身为先进技术太阳望远镜)，该望远镜将由美国国家太阳天文台(NSO)安装在夏威夷的哈雷阿卡拉火山上。镜面支撑设计是由以下需求驱动的:(1)在望远镜运行条件下，最大限度地减少支撑引起的镜面变形;(2)将镜面塑造成所需的轮廓;(3)提供抗风荷载的高刚度。为了满足这些要求，AMOS提出了一种创新的支撑设计，由118个轴向致动器和24个横向致动器组成。轴向支撑是基于耦合的液压和气动执行器。液压部分是一个被动系统，其主要功能是支撑具有高刚度的镜面重量。气动部分是主动控制的，以补偿由反射镜支架本身或望远镜光学链中的任何其他元件产生的低阶波前像差。在包括有限元、热学和光学模型在内的综合分析循环的帮助下，对支架的性能及其是否满足要求进行了评估。
{"title":"Design and analysis of an active optics system for a 4-m telescope mirror combining hydraulic and pneumatic supports","authors":"G. Lousberg, V. Moreau, J. Schumacher, M. Piérard, Aude Somja, P. Gloesener, C. Flebus","doi":"10.1117/12.2191272","DOIUrl":"https://doi.org/10.1117/12.2191272","url":null,"abstract":"AMOS has developed a hybrid active optics system that combines hydraulic and pneumatic properties of actuators to support a 4-m primary mirror. The mirror is intended to be used in the Daniel K. Inouye Solar Telescope (DKIST, formerly the Advanced Technology Solar Telescope) that will be installed by the National Solar Observatory (NSO) atop the Haleakala volcano in Hawaii. The mirror support design is driven by the needs of (1) minimizing the support-induced mirror distortions under telescope operating conditions, (2) shaping the mirror surface to the desired profile, and (3) providing a high stiffness against wind loads. In order to fulfill these requirements, AMOS proposes an innovative support design that consist of 118 axial actuators and 24 lateral actuators. The axial support is based on coupled hydraulic and pneumatic actuators. The hydraulic part is a passive system whose main function is to support the mirror weight with a high stiffness. The pneumatic part is actively controlled so as to compensate for low-order wavefront aberrations that are generated by the mirror support itself or by any other elements in the telescope optical chain. The performances of the support and its adequacy with the requirements are assessed with the help of a comprehensive analysis loop involving finite-element, thermal and optical modellings.","PeriodicalId":212434,"journal":{"name":"SPIE Optical Systems Design","volume":"381 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124743389","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 micro-optical array projector is a new and innovative possibility to project patterns onto arbitrary shaped surfaces1 . In contrast to single-aperture systems the illuminance of the projected image is raised by only increasing the lateral extent of the projector while keeping the length constant. Thanks to the setup - analogous to a fly’s eye condenser – we obtain a very compact design with homogenization of illumination. The images to be projected are presented as arbitrarily curved CAD-objects. Because of its complexity, the first attempt was a chief-ray backtrace implemented into a CAD-program, with the individual projectorlets modelled as pinhole cameras. With this principle one can trace the slides for several applications like the projection on perpendicular, as well as tilted and curved surfaces. Since aberrations cannot be considered with the simple CAD backtrace described above, we used the commercially available raytracer Zemax®, controlled by a macro, working in conjunction with a CADprogram for improved slide mask generation. Despite both methods, depending on the complexity of the optical system, are generating the fundamental mask data, the paper will show that there is a tradeoff between calculation time and accuracy. Based on this evaluation we will discuss further development as well as the possibility of improvement concerning the calculation methods. The different methods were investigated to determine their advantages and disadvantages. This provides the basis for the scope of application. Further we will demonstrate simulations as well as results obtained with built demonstrators.
{"title":"Array projector design for projection on arbitrarily curved surfaces","authors":"S. Fischer, P. Schreiber, A. Riedel, M. Sieler","doi":"10.1117/12.2191333","DOIUrl":"https://doi.org/10.1117/12.2191333","url":null,"abstract":"The micro-optical array projector is a new and innovative possibility to project patterns onto arbitrary shaped surfaces1 . In contrast to single-aperture systems the illuminance of the projected image is raised by only increasing the lateral extent of the projector while keeping the length constant. Thanks to the setup - analogous to a fly’s eye condenser – we obtain a very compact design with homogenization of illumination. The images to be projected are presented as arbitrarily curved CAD-objects. Because of its complexity, the first attempt was a chief-ray backtrace implemented into a CAD-program, with the individual projectorlets modelled as pinhole cameras. With this principle one can trace the slides for several applications like the projection on perpendicular, as well as tilted and curved surfaces. Since aberrations cannot be considered with the simple CAD backtrace described above, we used the commercially available raytracer Zemax®, controlled by a macro, working in conjunction with a CADprogram for improved slide mask generation. Despite both methods, depending on the complexity of the optical system, are generating the fundamental mask data, the paper will show that there is a tradeoff between calculation time and accuracy. Based on this evaluation we will discuss further development as well as the possibility of improvement concerning the calculation methods. The different methods were investigated to determine their advantages and disadvantages. This provides the basis for the scope of application. Further we will demonstrate simulations as well as results obtained with built demonstrators.","PeriodicalId":212434,"journal":{"name":"SPIE Optical Systems Design","volume":"82 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125117026","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}
F. Bruder, T. Fäcke, R. Hagen, Dennis Hönel, E. Orselli, C. Rewitz, T. Rölle, G. Walze
For a long time volume Holographic Optical Elements (vHOE) have been discussed as an alternative, but were hampered by a lack of suitable materials. They provide several benefits over surface corrugated diffractive optical element like high diffraction efficiency due to their ability to reconstruct a single diffraction order, freedom of optical design by freely setting the replay angles and adjusting their bandwidth by a selection of the vHOE’s thickness. Additional interesting features are related to their high Bragg selectivity providing transparent films for off-Bragg illumination. In this paper we report on our newly developed photopolymer film technology (Bayfol® HX) that uniquely requires no post processing after holographic exposure. We explain the governing non-local polymerization driven diffusion process leading to an active mass transport triggered by constructive interference. Key aspects of the recording process and their impact on index modulation formation is discussed. The influence on photopolymer film thickness on the bandwidth is shown. A comparison between coupled wave theory (CWT) simulation and experimental results is given. There are two basic recording geometries: reflection and transmission vHOEs. We explain consequences of how to record them properly and discuss in more detail the special challenges in transmission hologram recording. Here beam ratio and customization of photopolymer film properties can be applied most beneficially to achieve highest diffraction efficiency.
{"title":"Diffractive optics with high Bragg selectivity: volume holographic optical elements in Bayfol® HX photopolymer film","authors":"F. Bruder, T. Fäcke, R. Hagen, Dennis Hönel, E. Orselli, C. Rewitz, T. Rölle, G. Walze","doi":"10.1117/12.2191587","DOIUrl":"https://doi.org/10.1117/12.2191587","url":null,"abstract":"For a long time volume Holographic Optical Elements (vHOE) have been discussed as an alternative, but were hampered by a lack of suitable materials. They provide several benefits over surface corrugated diffractive optical element like high diffraction efficiency due to their ability to reconstruct a single diffraction order, freedom of optical design by freely setting the replay angles and adjusting their bandwidth by a selection of the vHOE’s thickness. Additional interesting features are related to their high Bragg selectivity providing transparent films for off-Bragg illumination. In this paper we report on our newly developed photopolymer film technology (Bayfol® HX) that uniquely requires no post processing after holographic exposure. We explain the governing non-local polymerization driven diffusion process leading to an active mass transport triggered by constructive interference. Key aspects of the recording process and their impact on index modulation formation is discussed. The influence on photopolymer film thickness on the bandwidth is shown. A comparison between coupled wave theory (CWT) simulation and experimental results is given. There are two basic recording geometries: reflection and transmission vHOEs. We explain consequences of how to record them properly and discuss in more detail the special challenges in transmission hologram recording. Here beam ratio and customization of photopolymer film properties can be applied most beneficially to achieve highest diffraction efficiency.","PeriodicalId":212434,"journal":{"name":"SPIE Optical Systems Design","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2015-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123605362","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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