The continuing trend towards lightweight construction and the associated machining rates of up to 95 % lead to an increased use of high-performance materials. The ever growing demands on the strength and quality of components and the associated use of materials which are hard to machine require the further development of new, economical machining techniques. In ultrasonic-assisted machining, an additional high-frequency vibration is superimposed on the conventional machining process. The vibration of the tool is usually excited axially or longitudinally to the workpiece, i.e. vertical to the cutting direction. An additional vibration overlay around the rotation axis (torsional) of the tool is also possible. This generates a vibration overlay in the cutting direction. The vibration initiation causes vibration amplitudes in the range of a few micrometers at the tool cutting edge. This leads in turn to a high-frequency change in the cutting speed or feed rate. Overall, an additional torsional vibration overlap can further reduce cutting forces, increase tool life and improve workpiece quality. In order for a grinding tool to generate a torsional vibration, a special tool was required that had to be designed by simulation. The formation of a torsional vibration was achieved by helical slots in the sonotrode. Depending on the angle of rotation and the length of the slots, a part of the axial vibration is converted into a torsional vibration by an axial excitation of the sonotrode. The aim in designing the slots was to achieve the highest possible vibration amplitude. Following the simulation, the slots were inserted into the tool in the corresponding optimum geometric position. Afterwards, the specially designed grinding tool was validated by machining the brittle-hard glass-ceramic material Zerodur. The first test results with the torsionally vibrating tool are presented in the following.
{"title":"Cutting high-performance materials with ultrasonically modulated cutting speed","authors":"Armin Reif, Sebastian Sitzberger, R. Rascher","doi":"10.1117/12.2565757","DOIUrl":"https://doi.org/10.1117/12.2565757","url":null,"abstract":"The continuing trend towards lightweight construction and the associated machining rates of up to 95 % lead to an increased use of high-performance materials. The ever growing demands on the strength and quality of components and the associated use of materials which are hard to machine require the further development of new, economical machining techniques. In ultrasonic-assisted machining, an additional high-frequency vibration is superimposed on the conventional machining process. The vibration of the tool is usually excited axially or longitudinally to the workpiece, i.e. vertical to the cutting direction. An additional vibration overlay around the rotation axis (torsional) of the tool is also possible. This generates a vibration overlay in the cutting direction. The vibration initiation causes vibration amplitudes in the range of a few micrometers at the tool cutting edge. This leads in turn to a high-frequency change in the cutting speed or feed rate. Overall, an additional torsional vibration overlap can further reduce cutting forces, increase tool life and improve workpiece quality. In order for a grinding tool to generate a torsional vibration, a special tool was required that had to be designed by simulation. The formation of a torsional vibration was achieved by helical slots in the sonotrode. Depending on the angle of rotation and the length of the slots, a part of the axial vibration is converted into a torsional vibration by an axial excitation of the sonotrode. The aim in designing the slots was to achieve the highest possible vibration amplitude. Following the simulation, the slots were inserted into the tool in the corresponding optimum geometric position. Afterwards, the specially designed grinding tool was validated by machining the brittle-hard glass-ceramic material Zerodur. The first test results with the torsionally vibrating tool are presented in the following.","PeriodicalId":422212,"journal":{"name":"Precision Optics Manufacturing","volume":"55 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":"122349305","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We report on a photonic process chain to manufacture optical elements by non-contact all laser based micro-processing. Firstly, pre-defined optics geometries are generated by high-precision 1030 nm femtosecond layer-by-layer ablation. In order to meet high surface quality requirements, inevitable stipulated for optical use, the surface of thus generated elements has to be smoothened by subsequent 10.6 μm CO2 laser polishing. To demonstrate this surface finishing process, a complex optic geometry i.e. an axicon array consisting of 37 individual axicons is fabricated within 23 minutes while the polishing shows a reduction of the surface roughness from 0.36 μm to 48 nm. The functionality of the fabricated optic is tested using the 1030 nm wavelength ultrashort pulsed laser. Several sub-Bessel beams exhibiting the typical zeroth-order Bessel beam intensity distribution are observed, in turn confirming the applied manufacturing process to be well applicable for the fabrication of complex optic geometries. Cross sections of the quasi-Bessel beam at the axicon in the middle of the array in both, x- and y-direction, show an almost identical intensity profile, indicating the high contour accuracy of the axicon. Detailed investigations of the axicon in the middle of the array show a tip rounding of 1.37 mm while the sub-beam behind this axicon is measured to have a diameter of 9.5 μm (FWHM) and a Bessel range in propagation direction of 8.0 mm (FWHM).
本文报道了一种非接触式全激光微加工制造光学元件的光子工艺链。首先，通过高精度1030nm飞秒逐层烧蚀生成预先定义的光学几何形状。为了满足光学使用中不可避免的高表面质量要求，由此产生的元件表面必须经过后续的10.6 μm CO2激光抛光。为了演示这种表面抛光工艺，在23分钟内制造了一个复杂的光学几何结构，即由37个单独的轴突组成的轴突阵列，同时抛光显示表面粗糙度从0.36 μm降低到48 nm。利用波长为1030nm的超短脉冲激光器对所制备的光学器件进行了功能测试。观察到几个亚贝塞尔光束表现出典型的零阶贝塞尔光束强度分布，从而证实了应用的制造工艺可以很好地适用于复杂光学几何形状的制造。准贝塞尔光束在阵列中间轴突处的x和y方向的截面显示出几乎相同的强度分布，表明轴突的轮廓精度很高。对阵列中心轴突的详细研究表明，轴突后的子光束直径为9.5 μm (FWHM)，传播方向的贝塞尔范围为8.0 mm (FWHM)。
{"title":"Manufacturing of optical elements by non-contact laser processing","authors":"S. Schwarz, S. Rung, C. Esen, R. Hellmann","doi":"10.1117/12.2564713","DOIUrl":"https://doi.org/10.1117/12.2564713","url":null,"abstract":"We report on a photonic process chain to manufacture optical elements by non-contact all laser based micro-processing. Firstly, pre-defined optics geometries are generated by high-precision 1030 nm femtosecond layer-by-layer ablation. In order to meet high surface quality requirements, inevitable stipulated for optical use, the surface of thus generated elements has to be smoothened by subsequent 10.6 μm CO2 laser polishing. To demonstrate this surface finishing process, a complex optic geometry i.e. an axicon array consisting of 37 individual axicons is fabricated within 23 minutes while the polishing shows a reduction of the surface roughness from 0.36 μm to 48 nm. The functionality of the fabricated optic is tested using the 1030 nm wavelength ultrashort pulsed laser. Several sub-Bessel beams exhibiting the typical zeroth-order Bessel beam intensity distribution are observed, in turn confirming the applied manufacturing process to be well applicable for the fabrication of complex optic geometries. Cross sections of the quasi-Bessel beam at the axicon in the middle of the array in both, x- and y-direction, show an almost identical intensity profile, indicating the high contour accuracy of the axicon. Detailed investigations of the axicon in the middle of the array show a tip rounding of 1.37 mm while the sub-beam behind this axicon is measured to have a diameter of 9.5 μm (FWHM) and a Bessel range in propagation direction of 8.0 mm (FWHM).","PeriodicalId":422212,"journal":{"name":"Precision Optics Manufacturing","volume":"395 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133910865","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}
S. Trumm, W. Becken, Yohann Bénard, G. Esser, D. Uttenweiler
When developing optical systems, every element within the light path is considered in technical optics. In ophthalmic optics, however, spectacle lenses are usually designed to provide a given optical power at a position called vertex sphere, ignoring the actual imaging processing inside the eye. We have developed a novel technology (trade name DNEye® PRO) overcoming this practice. The computation of the wavefronts does not stop at the back surface of the spectacle lens but is continued right into the eye through its refracting surfaces. The assessment no longer takes place at the vertex sphere, but at the retina. This calculation is based on individual measurements of biometrical parameters of the eye and comprises the complex shapes of the wavefronts and of the refracting surfaces including their higher-order components. As a result, effects which arise from the individual structure of the eye and its components are considered giving rise to sharper imaging and better design retention.
{"title":"Simulating the actual imaging in the individual eye: a novel approach to calculating spectacle lenses","authors":"S. Trumm, W. Becken, Yohann Bénard, G. Esser, D. Uttenweiler","doi":"10.1117/12.2564665","DOIUrl":"https://doi.org/10.1117/12.2564665","url":null,"abstract":"When developing optical systems, every element within the light path is considered in technical optics. In ophthalmic optics, however, spectacle lenses are usually designed to provide a given optical power at a position called vertex sphere, ignoring the actual imaging processing inside the eye. We have developed a novel technology (trade name DNEye® PRO) overcoming this practice. The computation of the wavefronts does not stop at the back surface of the spectacle lens but is continued right into the eye through its refracting surfaces. The assessment no longer takes place at the vertex sphere, but at the retina. This calculation is based on individual measurements of biometrical parameters of the eye and comprises the complex shapes of the wavefronts and of the refracting surfaces including their higher-order components. As a result, effects which arise from the individual structure of the eye and its components are considered giving rise to sharper imaging and better design retention.","PeriodicalId":422212,"journal":{"name":"Precision Optics Manufacturing","volume":"31 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":"122228561","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. Ehret, Jan Spichtinger, M. Stavridis, M. Schulz
Large optics with diameters of up to 1.5 m are being used more and more in industry and science. Flatness measurements of these optics are needed with uncertainties down to a few ten nanometres. For slightly curved specimens with radii of curvature down to 10 m uncertainties in the sub-micrometre range are required. We are currently building a new form measurement system which aims to fulfil these requirements. It will be set up in 2020 and the first measurements will be carried out in 2021. The setup can be operated with different sensor heads which use deflectometric- or interferometricbased methods. We plan, amongst other things, to use Fizeau interferometers with aperture sizes of 10 mm, 100 mm and 150 mm. The mechanical and optical setup of this new system is presented and simulation results of conventional subaperture stitching methods for this system with an aperture of 100 mm are shown. We also discuss the different measurement methods for the absolute form measurement of these optics.
{"title":"Setup of a new form measurement system for flat and slightly curved optics with diameters up to 1.5 metres","authors":"G. Ehret, Jan Spichtinger, M. Stavridis, M. Schulz","doi":"10.1117/12.2564912","DOIUrl":"https://doi.org/10.1117/12.2564912","url":null,"abstract":"Large optics with diameters of up to 1.5 m are being used more and more in industry and science. Flatness measurements of these optics are needed with uncertainties down to a few ten nanometres. For slightly curved specimens with radii of curvature down to 10 m uncertainties in the sub-micrometre range are required. We are currently building a new form measurement system which aims to fulfil these requirements. It will be set up in 2020 and the first measurements will be carried out in 2021. The setup can be operated with different sensor heads which use deflectometric- or interferometricbased methods. We plan, amongst other things, to use Fizeau interferometers with aperture sizes of 10 mm, 100 mm and 150 mm. The mechanical and optical setup of this new system is presented and simulation results of conventional subaperture stitching methods for this system with an aperture of 100 mm are shown. We also discuss the different measurement methods for the absolute form measurement of these optics.","PeriodicalId":422212,"journal":{"name":"Precision Optics Manufacturing","volume":"1 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":"130618877","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}
Michael F. Benisch, O. Fähnle, R. Rascher, W. Bogner
The Preston-equation implies, that, besides the relative speed υrel and a specific constant KP, the pressure p plays a significant role for the removal rate when polishing an optical component. This paper demonstrates a possibility for a qualitative evaluation of the pressure distribution before the polishing process. A pressure-sensitive foil is used as a gauge for pressure measurement. The effectiveness of this measuring method is explained. Specific weaknesses and limitations in the use of these foils are discussed. A method for an integrated evaluation of the pressure on different spots of the polishing pad is proposed at the end of the paper.
{"title":"Force and pressure analysis during overarm polishing","authors":"Michael F. Benisch, O. Fähnle, R. Rascher, W. Bogner","doi":"10.1117/12.2564903","DOIUrl":"https://doi.org/10.1117/12.2564903","url":null,"abstract":"The Preston-equation implies, that, besides the relative speed υrel and a specific constant KP, the pressure p plays a significant role for the removal rate when polishing an optical component. This paper demonstrates a possibility for a qualitative evaluation of the pressure distribution before the polishing process. A pressure-sensitive foil is used as a gauge for pressure measurement. The effectiveness of this measuring method is explained. Specific weaknesses and limitations in the use of these foils are discussed. A method for an integrated evaluation of the pressure on different spots of the polishing pad is proposed at the end of the paper.","PeriodicalId":422212,"journal":{"name":"Precision Optics Manufacturing","volume":"6 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":"124293059","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Due to the advantages over conventional polishing strategies, polishing with non-Newtonian fluids are state of the art in precision shape correction of precision optical glass surfaces. The viscosity of such fluids is not constant since it changes as a function of shear rate and time. An example is during the shape correction by polishing with pitch or ice, where pitch flows slowly under its own weight and acts like a solid body during short periods of stress as its viscosity increases. One approach is to use thixotropic fluids like ketchup to reduce the roughness by polishing, without changing the shape of the sample. Tomato ketchup shows a time-dependent change in viscosity: the longer the ketchup undergoes shear stress, the lower is its viscosity. Therefore, in this article, a new processing is put forward to polishing glass surfaces with ketchup containing micro-sized Ce2O. Besides conventional ketchup, curry ketchup and an organic product were tested as well. An industrial robot onto the work piece surface guides the polishing head. The different types of ketchup are compared by means of roughness and shape accuracy and the potential regarding to manufacture high-precise optical glass surfaces.
{"title":"High precision glass polishing with ketchup","authors":"M. Schneckenburger, Melanie Schiffner, R. Börret","doi":"10.1117/12.2564867","DOIUrl":"https://doi.org/10.1117/12.2564867","url":null,"abstract":"Due to the advantages over conventional polishing strategies, polishing with non-Newtonian fluids are state of the art in precision shape correction of precision optical glass surfaces. The viscosity of such fluids is not constant since it changes as a function of shear rate and time. An example is during the shape correction by polishing with pitch or ice, where pitch flows slowly under its own weight and acts like a solid body during short periods of stress as its viscosity increases. One approach is to use thixotropic fluids like ketchup to reduce the roughness by polishing, without changing the shape of the sample. Tomato ketchup shows a time-dependent change in viscosity: the longer the ketchup undergoes shear stress, the lower is its viscosity. Therefore, in this article, a new processing is put forward to polishing glass surfaces with ketchup containing micro-sized Ce2O. Besides conventional ketchup, curry ketchup and an organic product were tested as well. An industrial robot onto the work piece surface guides the polishing head. The different types of ketchup are compared by means of roughness and shape accuracy and the potential regarding to manufacture high-precise optical glass surfaces.","PeriodicalId":422212,"journal":{"name":"Precision Optics Manufacturing","volume":"47 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":"124414164","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 quality of optical components such as lenses or mirrors can be described by shape errors and surface roughness. With increasing optic sizes, the stability of the polishing process becomes more and more important. If not empirically known, the optical surface must be measured after each polishing step. One approach is to mount sensors on the polishing head in order to measure process relevant quantities. On the basis of these data, Machine Learning algorithms can be applied for surface value prediction. The aim of this work is the stepwise development of an artificial neural network (ANN) in order to improve the accuracy of the models' prediction. The ANN is developed in the Python programming language using the Keras deep learning library. Beginning with simple network architecture and common training parameters. The model will then be optimized step-by-step through the implementation of different methods and Hyperparameter optimization (HPO). Data, which is generated by the sensor-integrated glass polishing head, is used to train the ANN-model. A representative part of these data is held back before, in order to validate the models' prediction. The so-called dataset contains measured values from multiple polishing runs, preceded by a design of experiment. After the model is trained on the dataset, it is able to predict the result of not yet performed polishing runs, with given polishing parameters. Concrete, the ANN is used to predict the resulting glass-surface quality, which includes the surface roughness and the shape accuracy, calculated by the material removal over time. The prediction by artificial neural networks reduces the polishing iterations and thus the production time.
{"title":"Machine learning model for robot polishing cell","authors":"M. Schneckenburger, L. Garcia-Barth, R. Börret","doi":"10.1117/12.2564633","DOIUrl":"https://doi.org/10.1117/12.2564633","url":null,"abstract":"The quality of optical components such as lenses or mirrors can be described by shape errors and surface roughness. With increasing optic sizes, the stability of the polishing process becomes more and more important. If not empirically known, the optical surface must be measured after each polishing step. One approach is to mount sensors on the polishing head in order to measure process relevant quantities. On the basis of these data, Machine Learning algorithms can be applied for surface value prediction. The aim of this work is the stepwise development of an artificial neural network (ANN) in order to improve the accuracy of the models' prediction. The ANN is developed in the Python programming language using the Keras deep learning library. Beginning with simple network architecture and common training parameters. The model will then be optimized step-by-step through the implementation of different methods and Hyperparameter optimization (HPO). Data, which is generated by the sensor-integrated glass polishing head, is used to train the ANN-model. A representative part of these data is held back before, in order to validate the models' prediction. The so-called dataset contains measured values from multiple polishing runs, preceded by a design of experiment. After the model is trained on the dataset, it is able to predict the result of not yet performed polishing runs, with given polishing parameters. Concrete, the ANN is used to predict the resulting glass-surface quality, which includes the surface roughness and the shape accuracy, calculated by the material removal over time. The prediction by artificial neural networks reduces the polishing iterations and thus the production time.","PeriodicalId":422212,"journal":{"name":"Precision Optics Manufacturing","volume":"13 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":"123683775","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 aim of our research was to study middle spatial frequency errors (MSFE) on optical surfaces. We investigate the surfaces after manufacturing processes to find out the main affecting factors and to choose the proper processing parameters to minimize the size of the errors. To find an appropriate parameter window we have to be able not only to define the factors, which lead to MSFE, but also to analyze the change of the error after next following production steps.
{"title":"On the metrology and analysis of MSF error","authors":"Olga Kukso, R. Rascher, M. Pohl, R. Boerret","doi":"10.1117/12.2566251","DOIUrl":"https://doi.org/10.1117/12.2566251","url":null,"abstract":"The aim of our research was to study middle spatial frequency errors (MSFE) on optical surfaces. We investigate the surfaces after manufacturing processes to find out the main affecting factors and to choose the proper processing parameters to minimize the size of the errors. To find an appropriate parameter window we have to be able not only to define the factors, which lead to MSFE, but also to analyze the change of the error after next following production steps.","PeriodicalId":422212,"journal":{"name":"Precision Optics Manufacturing","volume":"32 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":"134363800","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 this article a new way of fabricating micro-optics, especially micro lens arrays (MLA’s) with lens heights up to several hundreds of micrometers is shown. Existing methods of MLA fabrication are compared to the new approach. Also applications are presented. A novel short pulse CO2-laser system is used for the production, which allows pulse lengths down to 200 ns. In combination with a common galvo-scanner system, the micro lenses are preformed by an ablation process in tens of seconds. Here, different lens diameters, lens radii and array sizes can be produced. In a second step, the MLA is fire-polished with the same laser source. For this process step the laser is switched to cw-mode. The preformed lenses melt and get a defined radius as a result of the surface tension of the molten glass. Measurements of the resulting geometry are be presented. As the results show, the laser based micro lens array fabrication process has a high reproducibility, very high flexibility, short process times and can process different glasses like borosilicate, soda lime or fused silica.
{"title":"Micro lens arrays made by CO2-laser radiation","authors":"T. Schmidt, D. Conrad","doi":"10.1117/12.2566485","DOIUrl":"https://doi.org/10.1117/12.2566485","url":null,"abstract":"In this article a new way of fabricating micro-optics, especially micro lens arrays (MLA’s) with lens heights up to several hundreds of micrometers is shown. Existing methods of MLA fabrication are compared to the new approach. Also applications are presented. A novel short pulse CO2-laser system is used for the production, which allows pulse lengths down to 200 ns. In combination with a common galvo-scanner system, the micro lenses are preformed by an ablation process in tens of seconds. Here, different lens diameters, lens radii and array sizes can be produced. In a second step, the MLA is fire-polished with the same laser source. For this process step the laser is switched to cw-mode. The preformed lenses melt and get a defined radius as a result of the surface tension of the molten glass. Measurements of the resulting geometry are be presented. As the results show, the laser based micro lens array fabrication process has a high reproducibility, very high flexibility, short process times and can process different glasses like borosilicate, soda lime or fused silica.","PeriodicalId":422212,"journal":{"name":"Precision Optics Manufacturing","volume":"53 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":"133527331","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 production of complex shaped optical elements like non-standard aspheres, acylinders, or freeform elements are highly demanded. Thus, optical manufacturing technologies need to be developed for optical systems to design freeform surfaces. Reactive Plasma Jet (RPJ) is one of the most promising tools for freeform generation of fused silica, SiC, ULE® and silicon. However, there are severe limitations when this technique is used for the surface machining of optical glasses like N-BK7®. The chemical interaction between plasma generated active species and metal components of N-BK7 induces the formation of a residual layer in the plasma-surface contact zone and surrounding which can degrade the capability of acquiring the required surface profile. It is shown that elevated surface temperature can modify the residual layer leading to higher predictability of freeform machining results.
{"title":"Optical freeform generation of N-BK7 by fluorine‐based plasma jet machining","authors":"Faezeh Kazemi, G. Boehm, T. Arnold","doi":"10.1117/12.2564913","DOIUrl":"https://doi.org/10.1117/12.2564913","url":null,"abstract":"The production of complex shaped optical elements like non-standard aspheres, acylinders, or freeform elements are highly demanded. Thus, optical manufacturing technologies need to be developed for optical systems to design freeform surfaces. Reactive Plasma Jet (RPJ) is one of the most promising tools for freeform generation of fused silica, SiC, ULE® and silicon. However, there are severe limitations when this technique is used for the surface machining of optical glasses like N-BK7®. The chemical interaction between plasma generated active species and metal components of N-BK7 induces the formation of a residual layer in the plasma-surface contact zone and surrounding which can degrade the capability of acquiring the required surface profile. It is shown that elevated surface temperature can modify the residual layer leading to higher predictability of freeform machining results.","PeriodicalId":422212,"journal":{"name":"Precision Optics Manufacturing","volume":"1 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":"132679485","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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