A liquid crystal phase-stepped point diffraction interferometer (LCPDI) has been developed to measure optical wavefronts[1]. A locally generated reference beam is generated by diffraction from a microsphere embedded in a thin liquid crystal layer. Phase shifting is achieved by applying a voltage across the birefringent liquid crystals to shift the phase of the object beam without affecting the reference beam. The intended application for this instrument is the measurement of phase objects, such as optical elements and slowly varying fluids.
{"title":"Defocus Measurement Using A Liquid Crystal Point Diffraction Interferometer","authors":"C. Mercer, K. Creath","doi":"10.1364/oft.1994.pd2","DOIUrl":"https://doi.org/10.1364/oft.1994.pd2","url":null,"abstract":"A liquid crystal phase-stepped point diffraction interferometer (LCPDI) has been developed to measure optical wavefronts[1]. A locally generated reference beam is generated by diffraction from a microsphere embedded in a thin liquid crystal layer. Phase shifting is achieved by applying a voltage across the birefringent liquid crystals to shift the phase of the object beam without affecting the reference beam. The intended application for this instrument is the measurement of phase objects, such as optical elements and slowly varying fluids.","PeriodicalId":142307,"journal":{"name":"Optical Fabrication and Testing Workshop","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114775391","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}
Lateral (or transverse) information at either the exit pupil or the focal plane has been used in optical testing for quite some time[1]; however, aberrations can also be measured by using longitudinal intensity information. Geary and Peterson [2] showed that for an unobscured system, spherical aberration can be determined by taking an intensity scan along the optic axis near paraxial focus. In this paper, we describe how the same technique can be applied to systems containing a central obscuration and how the technique can be used to determine the location of paraxial focus. We also investigate the effects of coma and astigmatism. Experimental results demonstrate good agreement with theoretical predictions.
{"title":"Aberration Measurement Using Axial Intensity","authors":"Q. Gong, Smiley S. Hsu","doi":"10.1117/12.163190","DOIUrl":"https://doi.org/10.1117/12.163190","url":null,"abstract":"Lateral (or transverse) information at either the exit pupil or the focal plane has been used in optical testing for quite some time[1]; however, aberrations can also be measured by using longitudinal intensity information. Geary and Peterson [2] showed that for an unobscured system, spherical aberration can be determined by taking an intensity scan along the optic axis near paraxial focus. In this paper, we describe how the same technique can be applied to systems containing a central obscuration and how the technique can be used to determine the location of paraxial focus. We also investigate the effects of coma and astigmatism. Experimental results demonstrate good agreement with theoretical predictions.","PeriodicalId":142307,"journal":{"name":"Optical Fabrication and Testing Workshop","volume":"85 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1994-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121402629","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 optical substrate-coating interface is established by (1) the original polished condition of the substrate; (2) the substrate cleaning process; and (3) the environment of the coating process. The substrate-coating interface affects the coating adhesion properties, is where most coating defects and scatter sites are thought to initiate, and in some instances may control the structure of the coating as it is deposited. Often features appear on an optic after coating which could not be observed after cleaning and prior to coating. Because of the wide variety of possible substrate materials, surface problems, and contaminants, cleaning processes are constantly evolving. Our study has clearly shown that the coating appearance is dependent not only on the cleaning method, but especially on the initial character of the substrate surface.
{"title":"Polished Substrate Surface and Cleaning Study for Coated Optic Quality*","authors":"A. Tesar, W. Eickelberg, K. Koons, K. Davis","doi":"10.1364/oft.1992.wb11","DOIUrl":"https://doi.org/10.1364/oft.1992.wb11","url":null,"abstract":"The optical substrate-coating interface is established by (1) the original polished condition of the substrate; (2) the substrate cleaning process; and (3) the environment of the coating process. The substrate-coating interface affects the coating adhesion properties, is where most coating defects and scatter sites are thought to initiate, and in some instances may control the structure of the coating as it is deposited. Often features appear on an optic after coating which could not be observed after cleaning and prior to coating. Because of the wide variety of possible substrate materials, surface problems, and contaminants, cleaning processes are constantly evolving. Our study has clearly shown that the coating appearance is dependent not only on the cleaning method, but especially on the initial character of the substrate surface.","PeriodicalId":142307,"journal":{"name":"Optical Fabrication and Testing Workshop","volume":"40 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122852658","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}
Zerodur [1] is a glass-ceramic composite of technical importance in applications where temperature instabilites influence optical and mechanical performance. For example, it has been extensively used for earthbound and spaceborne telescope mirror substrates. Polished Zerodur surfaces of high quality have been required for laser gyro mirrors. Recent studies of optics in high power laser applications have indicated that the polished surface quality of substrates affects performance of high reflection coatings [2,3]. Thus, the interest in improving Zerodur polished surface quality has become more general. Beyond eliminating subsurface damage, high quality surfaces are produced by reducing the amount of hydrated material redeposited on the surface during polishing [4]. With the proper control of polishing parameters, such surfaces exhibit roughnesses of <1Å rms. It has been our goal to study Zerodur polishing to recommend a high surface quality polishing process which could be easily adapted to standard planetary continuous polishing machines and spindles. This summary contains information on a polishing process developed at LLNL which reproducibly provides high quality polished Zerodur surfaces at very high polishing efficiencies. A continuation of work is planned to more fully understand the polishing behaviors.
{"title":"Zerodur Polishing Process for High Surface Quality and High Efficiency*","authors":"A. Tesar, B. Fuchs","doi":"10.1364/oft.1992.wb9","DOIUrl":"https://doi.org/10.1364/oft.1992.wb9","url":null,"abstract":"Zerodur [1] is a glass-ceramic composite of technical importance in applications where temperature instabilites influence optical and mechanical performance. For example, it has been extensively used for earthbound and spaceborne telescope mirror substrates. Polished Zerodur surfaces of high quality have been required for laser gyro mirrors. Recent studies of optics in high power laser applications have indicated that the polished surface quality of substrates affects performance of high reflection coatings [2,3]. Thus, the interest in improving Zerodur polished surface quality has become more general. Beyond eliminating subsurface damage, high quality surfaces are produced by reducing the amount of hydrated material redeposited on the surface during polishing [4]. With the proper control of polishing parameters, such surfaces exhibit roughnesses of <1Å rms. It has been our goal to study Zerodur polishing to recommend a high surface quality polishing process which could be easily adapted to standard planetary continuous polishing machines and spindles. This summary contains information on a polishing process developed at LLNL which reproducibly provides high quality polished Zerodur surfaces at very high polishing efficiencies. A continuation of work is planned to more fully understand the polishing behaviors.","PeriodicalId":142307,"journal":{"name":"Optical Fabrication and Testing Workshop","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132932253","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 key to improving the performance of optics and optical systems is to reduce scattering and absorption losses in thin film coatings and in the underlying substrates. Scattering can be measured by collecting the light scattered into a hemisphere (total integrated scattering, or TIS) or as a function of angle. The scattering can be related via scalar or vector scattering theories to the root mean square roughness and other statistical properties of the samples. Surface roughness can be measured by a noncontact heterodyne interferometric technique or a diamond stylus profiling instrument. If the optics are too large to fit into the measuring instruments, replicas can be made of parts of the surface and analyzed using one of the above techniques. Subsurface damage produced by the polishing process can in some cases be determined by a light scattering technique. Absorption in substrates and coatings can be distinguished from absorption at air-film or film-substrate interfaces using adiabatic calorimetry. The techniques to be described can measure absorption in parts per thousand, scattered light in parts per million, and surface roughness down to nearly atomic dimensions. Examples of some of the higher performance optics made possible by the sensitive evaluation techniques will also be given.
{"title":"Surface Evaluation Techniques for the Optics of the Future","authors":"J. Bennett","doi":"10.1364/ON.11.7.000017","DOIUrl":"https://doi.org/10.1364/ON.11.7.000017","url":null,"abstract":"A key to improving the performance of optics and optical systems is to reduce scattering and absorption losses in thin film coatings and in the underlying substrates. Scattering can be measured by collecting the light scattered into a hemisphere (total integrated scattering, or TIS) or as a function of angle. The scattering can be related via scalar or vector scattering theories to the root mean square roughness and other statistical properties of the samples. Surface roughness can be measured by a noncontact heterodyne interferometric technique or a diamond stylus profiling instrument. If the optics are too large to fit into the measuring instruments, replicas can be made of parts of the surface and analyzed using one of the above techniques. Subsurface damage produced by the polishing process can in some cases be determined by a light scattering technique. Absorption in substrates and coatings can be distinguished from absorption at air-film or film-substrate interfaces using adiabatic calorimetry. The techniques to be described can measure absorption in parts per thousand, scattered light in parts per million, and surface roughness down to nearly atomic dimensions. Examples of some of the higher performance optics made possible by the sensitive evaluation techniques will also be given.","PeriodicalId":142307,"journal":{"name":"Optical Fabrication and Testing Workshop","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1985-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128372441","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}
Surface finishes of optical materials are greatly influenced by the size and type of abrasives that are used during the grinding, lapping, and polishing steps. This paper examines the additional characteristics of particle morphology and agglomeration as factors that will influence the surface quality. Different submicron aluminum oxide polishing powders and their influence on the polishing of different optical materials and the resulting surface finishes will be examined.
{"title":"Influence of particle morphology and agglomeration on the polishing behavior of aluminum oxide powders","authors":"F. McClung","doi":"10.1364/oft.1994.otuc6","DOIUrl":"https://doi.org/10.1364/oft.1994.otuc6","url":null,"abstract":"Surface finishes of optical materials are greatly influenced by the size and type of abrasives that are used during the grinding, lapping, and polishing steps. This paper examines the additional characteristics of particle morphology and agglomeration as factors that will influence the surface quality. Different submicron aluminum oxide polishing powders and their influence on the polishing of different optical materials and the resulting surface finishes will be examined.","PeriodicalId":142307,"journal":{"name":"Optical Fabrication and Testing Workshop","volume":"8 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115635617","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}
There are a number of commercial coolants available to the metal cutting industry. These coolants have been optimized for the various properties of specific metal types, and instructions are available for their use [1,2]. Recently, coolants advertised to be designed especially for the optical industry have become available. A grinding study to evaluate the performance of several metal and glass grinding coolants is being conducted at the Center for Optics Manufacturing. This paper presents some recent results for K7 optical glass.
{"title":"Coolant Performance in Bound Diamond Ring Tool Grinding of K7 Optical Glass","authors":"B. Puchebner, A. Feltz, W. Ng, S. Jacobs","doi":"10.1364/oft.1994.omc4","DOIUrl":"https://doi.org/10.1364/oft.1994.omc4","url":null,"abstract":"There are a number of commercial coolants available to the metal cutting industry. These coolants have been optimized for the various properties of specific metal types, and instructions are available for their use [1,2]. Recently, coolants advertised to be designed especially for the optical industry have become available. A grinding study to evaluate the performance of several metal and glass grinding coolants is being conducted at the Center for Optics Manufacturing. This paper presents some recent results for K7 optical glass.","PeriodicalId":142307,"journal":{"name":"Optical Fabrication and Testing Workshop","volume":"137 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127346506","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 optical performance of current electrically addressed spatial light modulators is impaired because of the low optical quality of the metal mirrors. The distortion in the metal film is accounted for by hillock formation during the sintering phase of the metallization stage [1]. There have been several techniques developed to reduce or eliminate hillock formation [2,3,4] all of which increase the complexity of the processing sequence. From an electrical point of view the hillocks are only problematic in multi-level metallization schemes where they can cause shorts between levels, therefore, the added work to eliminate hillock formation is only applied to lower level metal. The top level metal which is always used to provide the mirrors has no hillock reduction applied since electrically this is not necessary which results in low quality mirrors. Silicon fabrication foundries will not alter the fabrication sequence to suit one application which leaves only one way to improve the mirrors and that is by post-processing completed wafers and adding another level of metal.
{"title":"Improved optical performance of silicon backplane spatial light modulators using chemical-mechanical polishing","authors":"A. O'hara, D. Vass, I. Underwood","doi":"10.1364/oft.1994.otua3","DOIUrl":"https://doi.org/10.1364/oft.1994.otua3","url":null,"abstract":"The optical performance of current electrically addressed spatial light modulators is impaired because of the low optical quality of the metal mirrors. The distortion in the metal film is accounted for by hillock formation during the sintering phase of the metallization stage [1]. There have been several techniques developed to reduce or eliminate hillock formation [2,3,4] all of which increase the complexity of the processing sequence. From an electrical point of view the hillocks are only problematic in multi-level metallization schemes where they can cause shorts between levels, therefore, the added work to eliminate hillock formation is only applied to lower level metal. The top level metal which is always used to provide the mirrors has no hillock reduction applied since electrically this is not necessary which results in low quality mirrors. Silicon fabrication foundries will not alter the fabrication sequence to suit one application which leaves only one way to improve the mirrors and that is by post-processing completed wafers and adding another level of metal.","PeriodicalId":142307,"journal":{"name":"Optical Fabrication and Testing Workshop","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125918739","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}
So called "absolute" calibration of optical flats can be performed using a range of algorithms, each with its own limitations. At NIST we have implemented, and are intercomparing, several techniques.
{"title":"Absolute calibration of optical flats using a commercial phase measuring interferometer","authors":"C. Evans, W. Estler, Robert E. Parks","doi":"10.1364/oft.1992.wa3","DOIUrl":"https://doi.org/10.1364/oft.1992.wa3","url":null,"abstract":"So called \"absolute\" calibration of optical flats can be performed using a range of algorithms, each with its own limitations. At NIST we have implemented, and are intercomparing, several techniques.","PeriodicalId":142307,"journal":{"name":"Optical Fabrication and Testing Workshop","volume":"26 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123306004","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}
Matthew T. Chang, J. Greivenkamp, A. Lindquist, Tim M. Rich
An automated PC-based machine vision system has been developed for measuring subsurface damage in glass based on the ball dimpling method [1,2]. The software automatically processes an image of the dimple and returns the SSD value. This paper provides a preliminary comparison of the result from this system and the result obtained by conventional visual measurements.
{"title":"Subsurface Damage: Comparison of Automated and Visual Measurements","authors":"Matthew T. Chang, J. Greivenkamp, A. Lindquist, Tim M. Rich","doi":"10.1364/oft.1994.omd4","DOIUrl":"https://doi.org/10.1364/oft.1994.omd4","url":null,"abstract":"An automated PC-based machine vision system has been developed for measuring subsurface damage in glass based on the ball dimpling method [1,2]. The software automatically processes an image of the dimple and returns the SSD value. This paper provides a preliminary comparison of the result from this system and the result obtained by conventional visual measurements.","PeriodicalId":142307,"journal":{"name":"Optical Fabrication and Testing Workshop","volume":"08 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116377433","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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