Sebastian Sitzberger, J. Liebl, C. Trum, R. Rascher
The developed concept represents a universally applicable clamping system designed to fit in any measuring machine with any measuring principle. The design ensures that, as long as the lens remains clamped, the measurement results are reproducible. Form errors due to tension remain constant across all measuring and processing steps. The version presented in this paper was developed especially for small lenses in the diameter range up to 40 mm. On the one hand, the design allows for fast measurement of loose lenses. On the other hand, the device can also be used for measurement comparisons, since lenses can also be mounted permanently. In the following, the concept and first results of measurement tests are presented.
{"title":"Concept of a two-part clamping system for lenses in optical metrology","authors":"Sebastian Sitzberger, J. Liebl, C. Trum, R. Rascher","doi":"10.1117/12.2566547","DOIUrl":"https://doi.org/10.1117/12.2566547","url":null,"abstract":"The developed concept represents a universally applicable clamping system designed to fit in any measuring machine with any measuring principle. The design ensures that, as long as the lens remains clamped, the measurement results are reproducible. Form errors due to tension remain constant across all measuring and processing steps. The version presented in this paper was developed especially for small lenses in the diameter range up to 40 mm. On the one hand, the design allows for fast measurement of loose lenses. On the other hand, the device can also be used for measurement comparisons, since lenses can also be mounted permanently. In the following, the concept and first results of measurement tests are presented.","PeriodicalId":422212,"journal":{"name":"Precision Optics Manufacturing","volume":"81 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129772844","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}
During the development of an optical system, one comes to the point where you have to build the optically active element into a mechanical device that becomes part of the system. At this point you come across the well-known question that it is not only necessary to consider and ensure the quality of the individual element. It is also important to look at the entire component in order to identify potential influencing factors on the performance of the optical system. At the beginning of a two-year project at Technologiecampus Teisnach the polishing process of a nonlinear crystal as the crucial component of the optical system was being explored. This system is designed to create continuous wave laser beams in the deep UV range. The crystal has to be embedded between two prisms. Roughness and shape of the crystal is ensured via the polishing process which alone has many influencing factors and was examined at the beginning of the project. The quality of the crystal can be as good as it can be, but if the contacting prisms do not fit, the whole prism-coupled device will become unusable in the overall optical laser system. The performance of the laser can only be achieved by harmonizing all elements of the PCD and the PCD itself into the laser set-up. In the current phase of the project this question will be dealt with. The prism-coupled device is split up into its individual parts, which are the nonlinear crystal, the prisms as optical auxiliary components, micro screws and mechanical support. Going through the requirements to the properties of the crystal and their limitations, the influence of the PCD on the optical performance of the crystal is presented. Here, the main focus is placed on the mode of fixing the crystal between the prisms and on putting the stack of crystal and prisms in the laser beam. The influencing factors between the crystal, the prisms and the method of fixing the PCD are described.
{"title":"Influencing factors for a continuous wave UV-laser component","authors":"Jessica Stelzl, C. Wünsche, S. Höfer","doi":"10.1117/12.2564916","DOIUrl":"https://doi.org/10.1117/12.2564916","url":null,"abstract":"During the development of an optical system, one comes to the point where you have to build the optically active element into a mechanical device that becomes part of the system. At this point you come across the well-known question that it is not only necessary to consider and ensure the quality of the individual element. It is also important to look at the entire component in order to identify potential influencing factors on the performance of the optical system. At the beginning of a two-year project at Technologiecampus Teisnach the polishing process of a nonlinear crystal as the crucial component of the optical system was being explored. This system is designed to create continuous wave laser beams in the deep UV range. The crystal has to be embedded between two prisms. Roughness and shape of the crystal is ensured via the polishing process which alone has many influencing factors and was examined at the beginning of the project. The quality of the crystal can be as good as it can be, but if the contacting prisms do not fit, the whole prism-coupled device will become unusable in the overall optical laser system. The performance of the laser can only be achieved by harmonizing all elements of the PCD and the PCD itself into the laser set-up. In the current phase of the project this question will be dealt with. The prism-coupled device is split up into its individual parts, which are the nonlinear crystal, the prisms as optical auxiliary components, micro screws and mechanical support. Going through the requirements to the properties of the crystal and their limitations, the influence of the PCD on the optical performance of the crystal is presented. Here, the main focus is placed on the mode of fixing the crystal between the prisms and on putting the stack of crystal and prisms in the laser beam. The influencing factors between the crystal, the prisms and the method of fixing the PCD are described.","PeriodicalId":422212,"journal":{"name":"Precision Optics Manufacturing","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116495088","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}
M. Jung, C. Trum, Beate Schmidbauer, E. Willenborg, R. Rascher
The form generation of optical surfaces by grinding and mechanical polishing results in small sub surface damages in the form of micro cracks that conventionally have to be removed by further removal of the damaged surface layers. In order to reduce process time and material cost non-ablative methods for removal of micro cracks are desired. Utilising the low optical penetration depths of less than 10 μm for CO2-laser radiation in glass, the laser energy can be used to heat up and melt thin surface layers. Using a 1.5 kW CO2-laser, a quasi-line focus formed by a scanner unit and a constant feed speed, it is possible to close all micro cracks present in the rough grinded test surfaces (max. SSD-depth ~ 63 μm), while achieving a process time of less than 2 seconds for a Ø 30 mm N-BK7 lens, respectively 7.5 seconds for fused silica. With a Sa as low as 50 nm and low distortion from the original shape the surfaces can directly be conventionally polished, further reducing the process chain complexity.
通过研磨和机械抛光产生的光学表面会产生微裂纹形式的小亚表面损伤，通常必须通过进一步去除损坏的表面层来消除这些损伤。为了减少加工时间和材料成本，需要非烧蚀法去除微裂纹。利用co2激光在玻璃中的低光穿透深度小于10 μm，激光能量可以用来加热和熔化薄的表面层。使用1.5 kW的co2激光器，由扫描器单元形成的准线聚焦和恒定的进给速度，可以关闭粗糙研磨测试表面上存在的所有微裂纹。同时，对于Ø 30 mm N-BK7透镜的工艺时间小于2秒，而对于熔融二氧化硅透镜的工艺时间为7.5秒。由于Sa低至50 nm，并且与原始形状的畸变很小，因此可以直接对表面进行常规抛光，进一步降低了工艺链的复杂性。
{"title":"Non-ablative removal of sub surface damages in grinded optical glass substrates by controlled melting of thin surface layers using CO2-laser radiation","authors":"M. Jung, C. Trum, Beate Schmidbauer, E. Willenborg, R. Rascher","doi":"10.1117/12.2564801","DOIUrl":"https://doi.org/10.1117/12.2564801","url":null,"abstract":"The form generation of optical surfaces by grinding and mechanical polishing results in small sub surface damages in the form of micro cracks that conventionally have to be removed by further removal of the damaged surface layers. In order to reduce process time and material cost non-ablative methods for removal of micro cracks are desired. Utilising the low optical penetration depths of less than 10 μm for CO2-laser radiation in glass, the laser energy can be used to heat up and melt thin surface layers. Using a 1.5 kW CO2-laser, a quasi-line focus formed by a scanner unit and a constant feed speed, it is possible to close all micro cracks present in the rough grinded test surfaces (max. SSD-depth ~ 63 μm), while achieving a process time of less than 2 seconds for a Ø 30 mm N-BK7 lens, respectively 7.5 seconds for fused silica. With a Sa as low as 50 nm and low distortion from the original shape the surfaces can directly be conventionally polished, further reducing the process chain complexity.","PeriodicalId":422212,"journal":{"name":"Precision Optics Manufacturing","volume":"74 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114698799","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}
Christian Schober, C. Pruss, A. Herkommer, W. Osten
Nanometer resolution metrology is a significant topic in the development and production of complex shaped high precision optics. The Nanopositioning and Nanomeasuring Machine NPMM-200 at ITO is built for nanometer scale positioning in a large scale measurement volume of 200 mm x 200 mm x 25 mm. The concept of the machine is based on a high precision interferometrically controlled stage in a stable metrological frame made of glass-ceramic. In this frame, different types of sensors can be attached for measurement of surface topographies. In this contribution, we present the use of optical sensors, such as a fixed focus probe, for measuring of high precision aspheric and freeform optics with this new machine.
纳米分辨率测量是复杂形状高精度光学器件开发和生产中的一个重要课题。ITO的纳米定位和纳米测量机NPMM-200专为200 mm x 200 mm x 25 mm的大规模测量体积的纳米级定位而设计。该机器的概念是基于一个高精度的干涉测量控制阶段在一个稳定的计量框架由玻璃陶瓷制成。在这个框架中，可以附加不同类型的传感器来测量表面地形。在这篇文章中，我们介绍了使用光学传感器，如固定焦点探头，测量高精度非球面和自由曲面光学与这台新机器。
{"title":"The NPMM-200: large area high resolution for freeform surface measurement","authors":"Christian Schober, C. Pruss, A. Herkommer, W. Osten","doi":"10.1117/12.2564918","DOIUrl":"https://doi.org/10.1117/12.2564918","url":null,"abstract":"Nanometer resolution metrology is a significant topic in the development and production of complex shaped high precision optics. The Nanopositioning and Nanomeasuring Machine NPMM-200 at ITO is built for nanometer scale positioning in a large scale measurement volume of 200 mm x 200 mm x 25 mm. The concept of the machine is based on a high precision interferometrically controlled stage in a stable metrological frame made of glass-ceramic. In this frame, different types of sensors can be attached for measurement of surface topographies. In this contribution, we present the use of optical sensors, such as a fixed focus probe, for measuring of high precision aspheric and freeform optics with this new machine.","PeriodicalId":422212,"journal":{"name":"Precision Optics Manufacturing","volume":"33 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131104320","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}
At Deggendorf Institute of Technology a student project is currently under way to build a Stevick-Paul telescope for astrophotography. An important step in the overall development procedure of each telescope is the design of a beam-path and ensuring its suitability under optical and engineering aspects. The students performed this process in a sequential manner by using several different computer programs (e.g. MATLAB, Zemax, Creo Parametric). To accelerate the beam path design process, a Python program to automate the major part of the design process with minimum human supervision was created. The input data of the python program consists of ranges of the desired characteristics of the Stevick-Paul telescope, such as focal lengths, primary mirror diameters and tilts etc., mirror thickness and mount geometries, as well as the specific type of camera. After setting the input, the program creates 2D cross-sections of beam paths according to the formulas of D. Stevick and may introduce a flat fold mirror to reduce the overall system size as well as improve the accessibility of the focus plane. The subsequent assessment routine checks against the susceptibility for stray light and performs a complex analysis of the available installation space to ensure sufficient mechanical tolerances. In this way, collisions between mirrors, mounts and cameras are avoided and obstructions of the beam path are prevented. At any stage, the program can produce graphical representations of the beam paths. In this paper the computer-aided design of a telescope beam path with a focal length of 2400 mm is demonstrated. During development of the software, a subset of folded Stevick-Paul telescopes, in which certain components are parallel, was found. This subset may be useful to simplify the alignment procedure. In conclusion, further refinement of the software is necessary, although the program is already a useful aid for certain aspects when creating a beam path design.
{"title":"Computer-aided beam path generation and assessment for Stevick-Paul telescopes","authors":"M. Wagner, G. Fütterer","doi":"10.1117/12.2564852","DOIUrl":"https://doi.org/10.1117/12.2564852","url":null,"abstract":"At Deggendorf Institute of Technology a student project is currently under way to build a Stevick-Paul telescope for astrophotography. An important step in the overall development procedure of each telescope is the design of a beam-path and ensuring its suitability under optical and engineering aspects. The students performed this process in a sequential manner by using several different computer programs (e.g. MATLAB, Zemax, Creo Parametric). To accelerate the beam path design process, a Python program to automate the major part of the design process with minimum human supervision was created. The input data of the python program consists of ranges of the desired characteristics of the Stevick-Paul telescope, such as focal lengths, primary mirror diameters and tilts etc., mirror thickness and mount geometries, as well as the specific type of camera. After setting the input, the program creates 2D cross-sections of beam paths according to the formulas of D. Stevick and may introduce a flat fold mirror to reduce the overall system size as well as improve the accessibility of the focus plane. The subsequent assessment routine checks against the susceptibility for stray light and performs a complex analysis of the available installation space to ensure sufficient mechanical tolerances. In this way, collisions between mirrors, mounts and cameras are avoided and obstructions of the beam path are prevented. At any stage, the program can produce graphical representations of the beam paths. In this paper the computer-aided design of a telescope beam path with a focal length of 2400 mm is demonstrated. During development of the software, a subset of folded Stevick-Paul telescopes, in which certain components are parallel, was found. This subset may be useful to simplify the alignment procedure. In conclusion, further refinement of the software is necessary, although the program is already a useful aid for certain aspects when creating a beam path design.","PeriodicalId":422212,"journal":{"name":"Precision Optics Manufacturing","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131040616","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}
Finishing of optical components is one of the main challenging tasks in optics manufacturing. This includes precision polishing, smoothing, and surface modification, e.g. for subsequent contact bonding. Recent developments have shown that the use of dielectric barrier discharge plasmas at atmospheric pressure allows for the conception and realization of novel approaches for such surface finishing. Since this type of plasma stands out due a low gas temperature, it is also referred to as “cold” plasma. It is thus suitable for the treatment of temperature-sensitive optical media. In this contribution, selected applications of such plasmas in optics manufacturing are presented. First, it is shown that precision polishing of different optical media can be achieved by the use of direct plasma discharges with an inert process gas. By the plasma-induced selective removal of roughness peaks, a notable decrease in surface roughness of the initial value was obtained. Second, plasma-induced cleaning of optics surfaces including the underlying plasma-physical and plasmachemical mechanisms is presented. Here, not only surface-adherent carbonaceous contaminations, but also residues from polishing agents and other operating materials can be removed. Such cleaning results in several advantageous effects as for example an increase in laser-induced damage threshold or a modification in free surface energy, leading to an improved adhesion of coatings and cements. Finally, plasma treatment is suitable for refractive index matching of glass surfaces by a plasma-induced modification of the chemical composition of the near-surface glass layer.
{"title":"Applications of cold atmospheric pressure plasmas in optics manufacturing","authors":"C. Gerhard","doi":"10.1117/12.2564862","DOIUrl":"https://doi.org/10.1117/12.2564862","url":null,"abstract":"Finishing of optical components is one of the main challenging tasks in optics manufacturing. This includes precision polishing, smoothing, and surface modification, e.g. for subsequent contact bonding. Recent developments have shown that the use of dielectric barrier discharge plasmas at atmospheric pressure allows for the conception and realization of novel approaches for such surface finishing. Since this type of plasma stands out due a low gas temperature, it is also referred to as “cold” plasma. It is thus suitable for the treatment of temperature-sensitive optical media. In this contribution, selected applications of such plasmas in optics manufacturing are presented. First, it is shown that precision polishing of different optical media can be achieved by the use of direct plasma discharges with an inert process gas. By the plasma-induced selective removal of roughness peaks, a notable decrease in surface roughness of the initial value was obtained. Second, plasma-induced cleaning of optics surfaces including the underlying plasma-physical and plasmachemical mechanisms is presented. Here, not only surface-adherent carbonaceous contaminations, but also residues from polishing agents and other operating materials can be removed. Such cleaning results in several advantageous effects as for example an increase in laser-induced damage threshold or a modification in free surface energy, leading to an improved adhesion of coatings and cements. Finally, plasma treatment is suitable for refractive index matching of glass surfaces by a plasma-induced modification of the chemical composition of the near-surface glass layer.","PeriodicalId":422212,"journal":{"name":"Precision Optics Manufacturing","volume":"118 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128447696","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}
High numerical aperture optical elements are relied on for the most demanding applications in optical imaging but pose a significant challenge for conventional metrology techniques. Laser Fizeau interferometers provide a flexible measurement platform for measuring spherical optics by offering a common path configuration to test spherical optics against a convex reference surface. However, in this configuration, traditional piezoelectric transducer (PZT) based phase shifters produce non-uniform phase shifts which vary across the aperture as the spherical reference surface is translated along the optical axis. While these errors are negligible for low numerical aperture optics, the phase shift errors quickly become significant for high numerical aperture optics. The phase shift nonuniformity results in fringe print through and phase ripple artifacts which limit overall accuracy of phase shifted interferometry (PSI) measurements. Spectrally controlled interferometry (SCI) is a method which produces localized, high contrast interference fringes in non-zero optical path length cavities through tailored control of the sources spectral distribution. In addition to fringe location, fringe phase is also controlled through spectrum manipulation without mechanical motion or compensation. As a consequence, the SCI method produces uniform, full-aperture phase shifts with a high degree of linearity regardless of numerical aperture; thus, phase shift errors associated with traditional PZTs can be eliminated. Furthermore, because SCI is a source driven method, it can easily be integrated with any Fizeau interferometer. In this paper, we present the fundamental background for SCI and the advantages of the method as they apply to the measurement of high numerical aperture spherical optics. Additionally, we compare PSI measurements between a traditional laser Fizeau interferometer with PZT based phase shifters and an SCI Fizeau interferometer. Existing methods to this problem are discussed and compared with the presented SCI method, as well.
{"title":"Spectrally controlled interferometry for high numerical aperture spherical cavity measurements","authors":"C. Salsbury, Donald A. Pearson, Artur Olszak","doi":"10.1117/12.2527151","DOIUrl":"https://doi.org/10.1117/12.2527151","url":null,"abstract":"High numerical aperture optical elements are relied on for the most demanding applications in optical imaging but pose a significant challenge for conventional metrology techniques. Laser Fizeau interferometers provide a flexible measurement platform for measuring spherical optics by offering a common path configuration to test spherical optics against a convex reference surface. However, in this configuration, traditional piezoelectric transducer (PZT) based phase shifters produce non-uniform phase shifts which vary across the aperture as the spherical reference surface is translated along the optical axis. While these errors are negligible for low numerical aperture optics, the phase shift errors quickly become significant for high numerical aperture optics. The phase shift nonuniformity results in fringe print through and phase ripple artifacts which limit overall accuracy of phase shifted interferometry (PSI) measurements. Spectrally controlled interferometry (SCI) is a method which produces localized, high contrast interference fringes in non-zero optical path length cavities through tailored control of the sources spectral distribution. In addition to fringe location, fringe phase is also controlled through spectrum manipulation without mechanical motion or compensation. As a consequence, the SCI method produces uniform, full-aperture phase shifts with a high degree of linearity regardless of numerical aperture; thus, phase shift errors associated with traditional PZTs can be eliminated. Furthermore, because SCI is a source driven method, it can easily be integrated with any Fizeau interferometer. In this paper, we present the fundamental background for SCI and the advantages of the method as they apply to the measurement of high numerical aperture spherical optics. Additionally, we compare PSI measurements between a traditional laser Fizeau interferometer with PZT based phase shifters and an SCI Fizeau interferometer. Existing methods to this problem are discussed and compared with the presented SCI method, as well.","PeriodicalId":422212,"journal":{"name":"Precision Optics Manufacturing","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114506984","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}
To meet stringent automotive safety requirements, car taillights typically incorporate retroreflective elements. In addition to their retroreflective role, these structures are also used for lighting/aesthetic/styling purposes. The most common type of automotive retroreflector (RR) – also known as reflex reflector – is characterized by a corner-cube (CC) geometry that has been fabricated for more than 60 years through a conventional pin-bundling technology. While accurate, this manufacturing approach remains time-consuming, expensive and over-constraining in terms of the RR design. To address this, alternate RR fabrication pathways have been developed and this study outlines the capabilities of a novel approach including milestones, setbacks, advantages and disadvantages. Corner-cube geometry includes three mutually orthogonal facets that meet at a common vertex/apex. This configuration precludes the use of most material removal techniques involving rotational tools. To address this, an alternate RR shape called right triangular prism (RTP) was proposed. This geometry is amenable to diamond-based single point cutting approaches, but its optical performance proved to not be identical with that conventional CC RR. The successful fabrication of RTP RRs was demonstrated in acrylic and quality/functionality of the prototype were assessed through both metrological and optical means. Surface quality Ra of less than 20 nm was achieved through an adequate combination of multi-axis machine tool kinematics and ultraprecise single point tool geometry. This cutting technique worked well on non-ferrous, but not on ferrous materials. Nevertheless, an alternative strategy involving micromilling has been developed for cutting RTPs in ferrous substrates. The successful fabrication of tooling inserts has been completed such that injection molded replicas of RTP RRs will be produced in the future. It is expected that the development of cutting-based RR fabrication strategies along with the associate knowledge on the underlying cutting mechanics will enable a broader diversity of RR designs in the future.
{"title":"Ultraprecise micromachining of retroreflective structures","authors":"N. Milliken, E. Bordatchev, O. R. Tutunea-Fatan","doi":"10.1117/12.2526434","DOIUrl":"https://doi.org/10.1117/12.2526434","url":null,"abstract":"To meet stringent automotive safety requirements, car taillights typically incorporate retroreflective elements. In addition to their retroreflective role, these structures are also used for lighting/aesthetic/styling purposes. The most common type of automotive retroreflector (RR) – also known as reflex reflector – is characterized by a corner-cube (CC) geometry that has been fabricated for more than 60 years through a conventional pin-bundling technology. While accurate, this manufacturing approach remains time-consuming, expensive and over-constraining in terms of the RR design. To address this, alternate RR fabrication pathways have been developed and this study outlines the capabilities of a novel approach including milestones, setbacks, advantages and disadvantages. Corner-cube geometry includes three mutually orthogonal facets that meet at a common vertex/apex. This configuration precludes the use of most material removal techniques involving rotational tools. To address this, an alternate RR shape called right triangular prism (RTP) was proposed. This geometry is amenable to diamond-based single point cutting approaches, but its optical performance proved to not be identical with that conventional CC RR. The successful fabrication of RTP RRs was demonstrated in acrylic and quality/functionality of the prototype were assessed through both metrological and optical means. Surface quality Ra of less than 20 nm was achieved through an adequate combination of multi-axis machine tool kinematics and ultraprecise single point tool geometry. This cutting technique worked well on non-ferrous, but not on ferrous materials. Nevertheless, an alternative strategy involving micromilling has been developed for cutting RTPs in ferrous substrates. The successful fabrication of tooling inserts has been completed such that injection molded replicas of RTP RRs will be produced in the future. It is expected that the development of cutting-based RR fabrication strategies along with the associate knowledge on the underlying cutting mechanics will enable a broader diversity of RR designs in the future.","PeriodicalId":422212,"journal":{"name":"Precision Optics Manufacturing","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117268431","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}
Plasma Jet Machining is an established process in ultra-precision surface manufacturing. Removal of several nanometers up to millimeters can be achieved using the atmospheric pressure reactive plasma jet as a non-mechanical tool. Surface form measuring techniques have to be improved equally, to further enhance the deterministic machining. Exact knowledge of the instrument transfer function is necessary to distinguish measurement artefacts and reliable measurement results. Precise sinusoidal surface structures prepared by plasma jet etching can be used as calibration elements to determine the instrument transfer function, e.g. slope-measuring devices like Nanometer Optical component measuring Machine (NOM). The steps for manufacturing such calibration elements including theoretical considerations, adjustment of the plasma jet parameters and implementations on different substrates are presented. Finally, a chirped sinusoidal structure on a singlecrystalline silicon slab is fabricated.
{"title":"Next generation of a linear chirped slope profile fabricated by plasma jet machining","authors":"H. Müller, G. Böhm, T. Arnold","doi":"10.1117/12.2526746","DOIUrl":"https://doi.org/10.1117/12.2526746","url":null,"abstract":"Plasma Jet Machining is an established process in ultra-precision surface manufacturing. Removal of several nanometers up to millimeters can be achieved using the atmospheric pressure reactive plasma jet as a non-mechanical tool. Surface form measuring techniques have to be improved equally, to further enhance the deterministic machining. Exact knowledge of the instrument transfer function is necessary to distinguish measurement artefacts and reliable measurement results. Precise sinusoidal surface structures prepared by plasma jet etching can be used as calibration elements to determine the instrument transfer function, e.g. slope-measuring devices like Nanometer Optical component measuring Machine (NOM). The steps for manufacturing such calibration elements including theoretical considerations, adjustment of the plasma jet parameters and implementations on different substrates are presented. Finally, a chirped sinusoidal structure on a singlecrystalline silicon slab is fabricated.","PeriodicalId":422212,"journal":{"name":"Precision Optics Manufacturing","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132491651","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 the course of the ever-increasing demand of high-performance optical components, dielectric coating processes are the key technology for the refinement of optics, ensuring their functionality. These optics are based on optical interference coatings, which are formed by a layer stack of alternating transparent single layers of high and low refractive index material. Assuming that turbidity as well as defects embedded in coatings are considered as a primary factor limiting the quality of optical coatings, the level of cleaning the substrates before coating has to be extremely high. Particular importance is attached to the interface between the layer stack and the substrate, especially to the interaction during the transition from the glass surface to the coating during the manufacturing process. This interaction is assumed to be caused by polishing, by corrosion during storage time or by effects during cleaning of the substrate before coating. Thus, it is necessary to characterize each type of defect and to define which technique is adequate to analyze each one of them efficiently. The project aims to raise the awareness and knowledge in terms of what happens during the coating process and, in particular, to understand the physical processes at the substrate during the manufacturing process. After analyzing the material flow, first focus was set on the cleaning procedure. It is assumed that one of the main influences on defects in the interface is the chemical cleaning. Chemical reactions on the surface of the glass substrate may occur due to additional effects of external components and elevated temperature in the washing basins.
{"title":"Cleaning effects in optical layers: error characteristics and analysis methods","authors":"E. M. Zambrano, C. Wünsche, L. Mechold, S. Herr","doi":"10.1117/12.2527974","DOIUrl":"https://doi.org/10.1117/12.2527974","url":null,"abstract":"In the course of the ever-increasing demand of high-performance optical components, dielectric coating processes are the key technology for the refinement of optics, ensuring their functionality. These optics are based on optical interference coatings, which are formed by a layer stack of alternating transparent single layers of high and low refractive index material. Assuming that turbidity as well as defects embedded in coatings are considered as a primary factor limiting the quality of optical coatings, the level of cleaning the substrates before coating has to be extremely high. Particular importance is attached to the interface between the layer stack and the substrate, especially to the interaction during the transition from the glass surface to the coating during the manufacturing process. This interaction is assumed to be caused by polishing, by corrosion during storage time or by effects during cleaning of the substrate before coating. Thus, it is necessary to characterize each type of defect and to define which technique is adequate to analyze each one of them efficiently. The project aims to raise the awareness and knowledge in terms of what happens during the coating process and, in particular, to understand the physical processes at the substrate during the manufacturing process. After analyzing the material flow, first focus was set on the cleaning procedure. It is assumed that one of the main influences on defects in the interface is the chemical cleaning. Chemical reactions on the surface of the glass substrate may occur due to additional effects of external components and elevated temperature in the washing basins.","PeriodicalId":422212,"journal":{"name":"Precision Optics Manufacturing","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121411386","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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