The Grinding Process Validation Approach (gPVA) presented in 2017 enables the determination of suitable parameter windows for grinding tools. The abrasion properties of grinding tools are determined experimentally. The collected data can be used to derive optimum parameters for defined grinding tasks so that service life, process stability and productivity can be maximized. In this publication, the gPVA method is used to compare different grinding tools. Differences in stock removal performance with identical specified tools from different manufacturers are investigated. In addition to that, recommended tools for fine grinding of fused silica are examined also.
{"title":"gPVA: a system for the classification of grinding tools","authors":"C. Vogt, O. Faehnle, R. Rascher","doi":"10.1117/12.2318695","DOIUrl":"https://doi.org/10.1117/12.2318695","url":null,"abstract":"The Grinding Process Validation Approach (gPVA) presented in 2017 enables the determination of suitable parameter windows for grinding tools. The abrasion properties of grinding tools are determined experimentally. The collected data can be used to derive optimum parameters for defined grinding tasks so that service life, process stability and productivity can be maximized. In this publication, the gPVA method is used to compare different grinding tools. Differences in stock removal performance with identical specified tools from different manufacturers are investigated. In addition to that, recommended tools for fine grinding of fused silica are examined also.","PeriodicalId":422212,"journal":{"name":"Precision Optics Manufacturing","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126363620","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}
Optical fabrication relies on precision metrology over a wide range of lateral scales. Consequently, an important performance parameter for Fizeau interferometers is the instrument transfer function (ITF), which specifies the system response as a function of surface spatial frequency. Advances in test procedures, instruments and automated analysis techniques now enable reliable ITF characterization independent of many traditional sources of error. Results here show the ITF for a commercial 100-mm aperture interferometer with spatial frequency response ranging from 0 to 1500 cycles per aperture
{"title":"Characterizing the resolving power of laser Fizeau interferometers","authors":"Torsten Glaschke, L. Deck, P. D. de Groot","doi":"10.1117/12.2317630","DOIUrl":"https://doi.org/10.1117/12.2317630","url":null,"abstract":"Optical fabrication relies on precision metrology over a wide range of lateral scales. Consequently, an important performance parameter for Fizeau interferometers is the instrument transfer function (ITF), which specifies the system response as a function of surface spatial frequency. Advances in test procedures, instruments and automated analysis techniques now enable reliable ITF characterization independent of many traditional sources of error. Results here show the ITF for a commercial 100-mm aperture interferometer with spatial frequency response ranging from 0 to 1500 cycles per aperture","PeriodicalId":422212,"journal":{"name":"Precision Optics Manufacturing","volume":"104 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122486996","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}
This research is focused on the link between manufacturing parameters and the resulting mid spatial frequency error in the manufacturing process of precision optics. This first publication focuses on the parameters of the grinding step. The Goal is to understand and avoid the appearance of the mid spatial frequency error and develop a simulation which is able to predict the resulting mid spatial frequency error for/of a manufacturing process.
{"title":"Simulation of MSF errors using Fourier transform","authors":"M. Pohl, R. Boerret, R. Rascher, Olga Kukso","doi":"10.1117/12.2317484","DOIUrl":"https://doi.org/10.1117/12.2317484","url":null,"abstract":"This research is focused on the link between manufacturing parameters and the resulting mid spatial frequency error in the manufacturing process of precision optics. This first publication focuses on the parameters of the grinding step. The Goal is to understand and avoid the appearance of the mid spatial frequency error and develop a simulation which is able to predict the resulting mid spatial frequency error for/of a manufacturing process.","PeriodicalId":422212,"journal":{"name":"Precision Optics Manufacturing","volume":"43 4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127584851","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}
Sebastian Sitzberger, C. Trum, R. Rascher, M. Zaeh
The effects, the extent and the importance of workpiece deformations, particularly lenses, caused by the weight of the workpiece itself, were examined in a previous paper1 . The considered deformations are in the single-digit to two-digit nanometer range. The investigation was carried out by FEM calculations. The conclusion of the previous aper was that a full-surface support of a workpiece in the processing of one surface presumably produces the best results. Furthermore, it was found that if the second functional surface is not to be touched in the process, a full contact lens mounting on its circumference is advisable. An alternative method for fixing precision lenses is therefore desirable. This can be accomplished in two steps. As a first step, the lens must be gripped at its periphery so that none of the optically functional surfaces of the lens is compromised. However, the complete circumference has to be fixated gaplessly because a punctual fixation has the disadvantage of deforming the lens surface asymmetrically. As a second step, the freely hanging lens surface should be supported to minimize deformation. An approach had to be found that supports the surface like a solid bearing but at the same time does not touch it. Therefore, the usage of an incompressible fluid as a hydrostatic bearing for full-surface support is pursued. For this purpose, the bottom side of the lens has to be stored on water. The results of the FEM simulation showed that with a fluid bearing the resulting deformations can be drastically reduced in comparison to a freely hanging surface. Furthermore, under the right conditions, a resulting deformation comparable to a full surface solid support can be achieved. The content of this paper is a test series under laboratory conditions for a first validation of the theoretical results. Therefore, a prototype model to test a lens fixation with a fluid bearing was developed and manufactured. The resulting deformations were measured with an interferometer and the effects are discussed.
{"title":"Workpiece self-weight in precision optics manufacturing: compensation of workpiece deformations by a fluid bearing","authors":"Sebastian Sitzberger, C. Trum, R. Rascher, M. Zaeh","doi":"10.1117/12.2318577","DOIUrl":"https://doi.org/10.1117/12.2318577","url":null,"abstract":"The effects, the extent and the importance of workpiece deformations, particularly lenses, caused by the weight of the workpiece itself, were examined in a previous paper1 . The considered deformations are in the single-digit to two-digit nanometer range. The investigation was carried out by FEM calculations. The conclusion of the previous aper was that a full-surface support of a workpiece in the processing of one surface presumably produces the best results. Furthermore, it was found that if the second functional surface is not to be touched in the process, a full contact lens mounting on its circumference is advisable. An alternative method for fixing precision lenses is therefore desirable. This can be accomplished in two steps. As a first step, the lens must be gripped at its periphery so that none of the optically functional surfaces of the lens is compromised. However, the complete circumference has to be fixated gaplessly because a punctual fixation has the disadvantage of deforming the lens surface asymmetrically. As a second step, the freely hanging lens surface should be supported to minimize deformation. An approach had to be found that supports the surface like a solid bearing but at the same time does not touch it. Therefore, the usage of an incompressible fluid as a hydrostatic bearing for full-surface support is pursued. For this purpose, the bottom side of the lens has to be stored on water. The results of the FEM simulation showed that with a fluid bearing the resulting deformations can be drastically reduced in comparison to a freely hanging surface. Furthermore, under the right conditions, a resulting deformation comparable to a full surface solid support can be achieved. The content of this paper is a test series under laboratory conditions for a first validation of the theoretical results. Therefore, a prototype model to test a lens fixation with a fluid bearing was developed and manufactured. The resulting deformations were measured with an interferometer and the effects are discussed.","PeriodicalId":422212,"journal":{"name":"Precision Optics Manufacturing","volume":"88 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125636301","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}
Ultra-precision molded polymer optics range from high precision imaging objectives to tiny lenses like those used in camera modules for cell phones, where centration tolerances and filling of small features is a challenge. We propose a manufacturing process termed Compression Molded Polymer Aspheres (COMPAS). Polymer preforms are inserted into mold cavities, and isothermally heated above glass point. Novel tooling has been developed to produce high volumes of COMPAS optics at reasonable cost and cycle time, using large scale parallelization of mold cavities. First results of the COMPAS process are very encouraging: shape accuracy (<500 nm peak-to-valley), surface centration (<5 μm), and birefringence (<20 nm/cm) are well below values typically measured for injection molded lenses. COMPAS lenses are also gate free. We describe details of the on-axis turning of arrays and multi-cavities (DPI) and the COMPAS precision polymer molding process. We describe the metaphysical background of disruptive engineering based on physical principles, which is the reason behind developing DPI and COMPAS.
{"title":"Tight tolerances for large-volume precision-pressed plastic optics (COMPAS)","authors":"Marc Wielandts, Remi Wielandts, R. Leutz","doi":"10.1117/12.2318670","DOIUrl":"https://doi.org/10.1117/12.2318670","url":null,"abstract":"Ultra-precision molded polymer optics range from high precision imaging objectives to tiny lenses like those used in camera modules for cell phones, where centration tolerances and filling of small features is a challenge. We propose a manufacturing process termed Compression Molded Polymer Aspheres (COMPAS). Polymer preforms are inserted into mold cavities, and isothermally heated above glass point. Novel tooling has been developed to produce high volumes of COMPAS optics at reasonable cost and cycle time, using large scale parallelization of mold cavities. First results of the COMPAS process are very encouraging: shape accuracy (<500 nm peak-to-valley), surface centration (<5 μm), and birefringence (<20 nm/cm) are well below values typically measured for injection molded lenses. COMPAS lenses are also gate free. We describe details of the on-axis turning of arrays and multi-cavities (DPI) and the COMPAS precision polymer molding process. We describe the metaphysical background of disruptive engineering based on physical principles, which is the reason behind developing DPI and COMPAS.","PeriodicalId":422212,"journal":{"name":"Precision Optics Manufacturing","volume":"41 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123298319","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}
Nowadays Ion Beam Figuring (IBF) is a well-known finishing technique for the production of ultra-precise optical surfaces. The diameter of optics can be in the range of 5 mm up to 2000 mm. Newest in-house developments extend the range down to 1 mm, which follows the upcoming market for micro optical systems. Besides IBF, ion beam etching technology (IBE) enables roughness improvement by different methods. Feature sizes from < 100 nm up to > 10 μm can be smoothed. However, operational parameters of IBF or IBE technology need to be adapted to the optical element. Beside the right choice of ion beam sizes (tool size) to remove equivalent feature sizes of the optics, also the shape (concave/convex) is of importance to consider side effects like re-sputtering or contamination originating from the ion beam source. This article will tabulate the state of the art of ion beam technology for ultra-precise optics manufacturing considering all parameters and side effects for efficient optics finishing.
{"title":"Basics of ion beam figuring and challenges for real optics treatment","authors":"D. Schaefer","doi":"10.1117/12.2318572","DOIUrl":"https://doi.org/10.1117/12.2318572","url":null,"abstract":"Nowadays Ion Beam Figuring (IBF) is a well-known finishing technique for the production of ultra-precise optical surfaces. The diameter of optics can be in the range of 5 mm up to 2000 mm. Newest in-house developments extend the range down to 1 mm, which follows the upcoming market for micro optical systems. Besides IBF, ion beam etching technology (IBE) enables roughness improvement by different methods. Feature sizes from < 100 nm up to > 10 μm can be smoothed. However, operational parameters of IBF or IBE technology need to be adapted to the optical element. Beside the right choice of ion beam sizes (tool size) to remove equivalent feature sizes of the optics, also the shape (concave/convex) is of importance to consider side effects like re-sputtering or contamination originating from the ion beam source. This article will tabulate the state of the art of ion beam technology for ultra-precise optics manufacturing considering all parameters and side effects for efficient optics finishing.","PeriodicalId":422212,"journal":{"name":"Precision Optics Manufacturing","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123621334","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. Doetz, O. Dambon, F. Klocke, J. Lee, O. Fähnle, E. Langenbach
Ductile mode machining is usually applied for the optical finishing operation of e.g. tungsten carbide molds. One request for this mode is not to exceed the critical depth of cut hcu,crit characterized by the transition point from ductile to brittle material removal. Based on experimental investigations a formula for the critical depth of cut, relating the material specific properties Young’s-Modulus E, material hardness H and fracture toughness KC was developed by Bifano et. all [1]. Even when the influence of cutting conditions, like tool or process characteristics, are neglected the formula is widely used for setting up UPM machines ever since. However, previous investigations have shown that hcu,crit strongly depends on coolant fluid characteristic as well as on the compressive stress applied into the cutting zone by the use of tools with e.g. negative rank angles [2]. In this paper, we report on a ductile process analysis applying a recently developed method for process optimization in optics fabrication [3]. Following that trail, critical process parameters have been identified and their influences on the critical depth of cut hcu,crit have been tested experimentally in fundamental ruling tests. Among others, following parameters were identified and tested: (a) characteristics of the coolant used, (b) the pH value of the coolant, (c) the tool specifications of the applied diamond and (d) whether ultrasonic assistance (US) is being switched on or off. Depending on the applied set of process parameters and for the experimental data collected, maximum ductile mode material removal rates could be achieved with dcmax = 1600 nm. That way, a new formula was developed, which allows the prediction of the critical depth of cut depending on critical process parameters while machining binderless nanocrystalline tungsten carbide. The formula was set up based on experimental results and is one step towards extending Bifanos formula taking the influences of critical process parameters into account.
{"title":"Increasing critcal depth of cut in ductile mode machining of tungsten carbide by process parameter controlling","authors":"M. Doetz, O. Dambon, F. Klocke, J. Lee, O. Fähnle, E. Langenbach","doi":"10.1117/12.2318709","DOIUrl":"https://doi.org/10.1117/12.2318709","url":null,"abstract":"Ductile mode machining is usually applied for the optical finishing operation of e.g. tungsten carbide molds. One request for this mode is not to exceed the critical depth of cut hcu,crit characterized by the transition point from ductile to brittle material removal. Based on experimental investigations a formula for the critical depth of cut, relating the material specific properties Young’s-Modulus E, material hardness H and fracture toughness KC was developed by Bifano et. all [1]. Even when the influence of cutting conditions, like tool or process characteristics, are neglected the formula is widely used for setting up UPM machines ever since. However, previous investigations have shown that hcu,crit strongly depends on coolant fluid characteristic as well as on the compressive stress applied into the cutting zone by the use of tools with e.g. negative rank angles [2]. In this paper, we report on a ductile process analysis applying a recently developed method for process optimization in optics fabrication [3]. Following that trail, critical process parameters have been identified and their influences on the critical depth of cut hcu,crit have been tested experimentally in fundamental ruling tests. Among others, following parameters were identified and tested: (a) characteristics of the coolant used, (b) the pH value of the coolant, (c) the tool specifications of the applied diamond and (d) whether ultrasonic assistance (US) is being switched on or off. Depending on the applied set of process parameters and for the experimental data collected, maximum ductile mode material removal rates could be achieved with dcmax = 1600 nm. That way, a new formula was developed, which allows the prediction of the critical depth of cut depending on critical process parameters while machining binderless nanocrystalline tungsten carbide. The formula was set up based on experimental results and is one step towards extending Bifanos formula taking the influences of critical process parameters into account.","PeriodicalId":422212,"journal":{"name":"Precision Optics Manufacturing","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121418283","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A challenge of coaxial - measurement cavity based - interferometer is to realize an interference contrast in the vicinity of one and to realize a complete elimination of the parasitic reflections. Another challenge, which also exists in non-coaxial setups, is the phase transfer function of extended measurement cavities. Ideally, the surface under test (SUT) and the reference surface (REF) are both exactly imaged onto the detector plane. In practice, SUT and REF have to be placed within the depth of field (DOF), which refers to the object space. The term depth of focus refers to the image space. To avoid confusion, the depth of field might be referred to as DOOF (depth of object field) and the depth of focus might be referred to as DOIF (depth of image field). However, in many measurement situations, the REF is not placed within the DOOF, which is the small z-range, which is imaged onto the detector plane. Furthermore, the phase transfer function (PTF) of the REF and the image distortion of the REF are both dependent on the focal plane used to image the SUT onto the detector plane. Effects as phase deformation, image distortion and image blurring have to be taken into account when using extended measurement cavities. This can be done by using a look up table (LUT), which contains simulated and/or calibrated data. Thus, the related system error can be subtracted. A remaining challenge is an unknown object under test (OUT), which is measured by using a double path arrangement. The measured wave front depends on the two surfaces of the OUT and the position of the return mirror. For simplicity, a homogeneous substrate and a perfect return mirror might be presumed. The simulation of waves propagating within extended measurement cavities, as well as measurement results, will be discussed. In addition, the influence on the power spectral density (PSD) will be described. This is important for high end correction techniques as e.g. magneto rheological figuring (MRF) and ion beam figuring (IBF).
{"title":"Contribution of the phase transfer function of extended measurement cavities to mid spatial frequencies and the overall error budget","authors":"G. Fütterer, J. Liebl, A. Haberl","doi":"10.1117/12.2318711","DOIUrl":"https://doi.org/10.1117/12.2318711","url":null,"abstract":"A challenge of coaxial - measurement cavity based - interferometer is to realize an interference contrast in the vicinity of one and to realize a complete elimination of the parasitic reflections. Another challenge, which also exists in non-coaxial setups, is the phase transfer function of extended measurement cavities. Ideally, the surface under test (SUT) and the reference surface (REF) are both exactly imaged onto the detector plane. In practice, SUT and REF have to be placed within the depth of field (DOF), which refers to the object space. The term depth of focus refers to the image space. To avoid confusion, the depth of field might be referred to as DOOF (depth of object field) and the depth of focus might be referred to as DOIF (depth of image field). However, in many measurement situations, the REF is not placed within the DOOF, which is the small z-range, which is imaged onto the detector plane. Furthermore, the phase transfer function (PTF) of the REF and the image distortion of the REF are both dependent on the focal plane used to image the SUT onto the detector plane. Effects as phase deformation, image distortion and image blurring have to be taken into account when using extended measurement cavities. This can be done by using a look up table (LUT), which contains simulated and/or calibrated data. Thus, the related system error can be subtracted. A remaining challenge is an unknown object under test (OUT), which is measured by using a double path arrangement. The measured wave front depends on the two surfaces of the OUT and the position of the return mirror. For simplicity, a homogeneous substrate and a perfect return mirror might be presumed. The simulation of waves propagating within extended measurement cavities, as well as measurement results, will be discussed. In addition, the influence on the power spectral density (PSD) will be described. This is important for high end correction techniques as e.g. magneto rheological figuring (MRF) and ion beam figuring (IBF).","PeriodicalId":422212,"journal":{"name":"Precision Optics Manufacturing","volume":"29 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114293904","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}
R. Geyl, D. Bardon, R. Bourgois, N. Ferachoglou, E. Harel, C. Couteret
Green light for the construction of the 39-m aperture giant Extremely Large Telescope (ELT) was given by the European Southern Observatory (ESO) council on Dec 4th, 2014. Procurement of the key elements, especially the optics, was immediately initiated by ESO team. Up today, Safran Reosc was awarded all the key optical polishing and testing contracts with: 2015-07: contract for the Adaptive Optics M4 mirror thin glass petals, 2016-07: contract for the 4-m M2 convex mirror, 2017-02: contract for the 4-m M3 mirror. 2017-05: contract for polishing and intergation of the 931 1.45-m hexagonal segments for the giant 39-m M1 mirror assembly This paper is dedicated to highlighting the various challenges linked to these various optical fabrication projects and reporting about the progress of our work so far.
{"title":"First steps in ELT optics polishing","authors":"R. Geyl, D. Bardon, R. Bourgois, N. Ferachoglou, E. Harel, C. Couteret","doi":"10.1117/12.2317604","DOIUrl":"https://doi.org/10.1117/12.2317604","url":null,"abstract":"Green light for the construction of the 39-m aperture giant Extremely Large Telescope (ELT) was given by the European Southern Observatory (ESO) council on Dec 4th, 2014. Procurement of the key elements, especially the optics, was immediately initiated by ESO team. Up today, Safran Reosc was awarded all the key optical polishing and testing contracts with: 2015-07: contract for the Adaptive Optics M4 mirror thin glass petals, 2016-07: contract for the 4-m M2 convex mirror, 2017-02: contract for the 4-m M3 mirror. 2017-05: contract for polishing and intergation of the 931 1.45-m hexagonal segments for the giant 39-m M1 mirror assembly This paper is dedicated to highlighting the various challenges linked to these various optical fabrication projects and reporting about the progress of our work so far.","PeriodicalId":422212,"journal":{"name":"Precision Optics Manufacturing","volume":"493 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123890796","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 manufacturing of optical lenses has various steps. Generally, the manufacturing can be split up into the following steps: the workpiece is pre-ground with a coarse tool; it is then fine-ground with a finer tool. As the final polishing is a demanding and time-consuming process that cannot manage large removal rations not can it equalise rough shape errors, the starting quality and surface quality needs to be as high as possible. According to the current state of technology, ground lenses must be measured with tactile measuring techniques in order to detect shape errors. This is timeconsuming and expensive, and only two dimensional profiles can be measured. DefGO’s project objective is to introduce deflectometry as a new, three dimensional lens measuring standard. A problem with the application of deflectometry is that the object to be measured has to reflect enough light, which is not the case for ground glass with rough surfaces. DefGO’s solution is to wet the lens with a fluid to create a closed reflecting surface.
{"title":"DefGO","authors":"J. Liebl, C. Schopf, R. Rascher","doi":"10.1117/12.2318704","DOIUrl":"https://doi.org/10.1117/12.2318704","url":null,"abstract":"The manufacturing of optical lenses has various steps. Generally, the manufacturing can be split up into the following steps: the workpiece is pre-ground with a coarse tool; it is then fine-ground with a finer tool. As the final polishing is a demanding and time-consuming process that cannot manage large removal rations not can it equalise rough shape errors, the starting quality and surface quality needs to be as high as possible. According to the current state of technology, ground lenses must be measured with tactile measuring techniques in order to detect shape errors. This is timeconsuming and expensive, and only two dimensional profiles can be measured. DefGO’s project objective is to introduce deflectometry as a new, three dimensional lens measuring standard. A problem with the application of deflectometry is that the object to be measured has to reflect enough light, which is not the case for ground glass with rough surfaces. DefGO’s solution is to wet the lens with a fluid to create a closed reflecting surface.","PeriodicalId":422212,"journal":{"name":"Precision Optics Manufacturing","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2018-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115007112","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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