P. Pokorný, A. Mikš, J. Novák, P. Novák, S. Rinner
This work presents detailed theoretical analysis of the effect of finite dimensions of an amplitude diffraction grating to the edge response function of the Talbot imaging. A diffraction of a plane wave is studied as well as a diffraction of a spherical one. The derived formulas can be used to refine the description of field propagation behind the amplitude diffraction grating; therefore, an analysis and an improvement of current applications, where the Talbot effect is used, can be realised.
{"title":"Effect of finite dimensions of diffraction grating to Talbot imaging","authors":"P. Pokorný, A. Mikš, J. Novák, P. Novák, S. Rinner","doi":"10.1117/12.2256500","DOIUrl":"https://doi.org/10.1117/12.2256500","url":null,"abstract":"This work presents detailed theoretical analysis of the effect of finite dimensions of an amplitude diffraction grating to the edge response function of the Talbot imaging. A diffraction of a plane wave is studied as well as a diffraction of a spherical one. The derived formulas can be used to refine the description of field propagation behind the amplitude diffraction grating; therefore, an analysis and an improvement of current applications, where the Talbot effect is used, can be realised.","PeriodicalId":112965,"journal":{"name":"Optical Angular Momentum","volume":"87 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126055019","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}
Laser welding is a modern, widely used but still not really common method of welding. With increasing demands on the quality of the welds, it is usual to apply automated machine welding and with on-line monitoring of the welding process. The resulting quality of the weld is largely affected by the behavior of keyhole. However, its direct observation during the welding process is practically impossible and it is necessary to use indirect methods. At ISI we have developed optical methods of monitoring the process. Most advanced is an analysis of radiation of laser-induced plasma plume forming in the keyhole where changes in the frequency of the plasma bursts are monitored and evaluated using Fourier and autocorrelation analysis. Another solution, robust and suitable for industry, is based on the observation of the keyhole inlet opening through a coaxial camera mounted in the welding head and the subsequent image processing by computer vision methods. A high-speed camera is used to understand the dynamics of the plasma plume. Through optical spectroscopy of the plume, we can study the excitation of elements in a material. It is also beneficial to monitor the gas flow of shielding gas using schlieren method.
{"title":"Possibilities in optical monitoring of laser welding process","authors":"P. Horník, L. Mrňa, J. Pavelka","doi":"10.1117/12.2257234","DOIUrl":"https://doi.org/10.1117/12.2257234","url":null,"abstract":"Laser welding is a modern, widely used but still not really common method of welding. With increasing demands on the quality of the welds, it is usual to apply automated machine welding and with on-line monitoring of the welding process. The resulting quality of the weld is largely affected by the behavior of keyhole. However, its direct observation during the welding process is practically impossible and it is necessary to use indirect methods. At ISI we have developed optical methods of monitoring the process. Most advanced is an analysis of radiation of laser-induced plasma plume forming in the keyhole where changes in the frequency of the plasma bursts are monitored and evaluated using Fourier and autocorrelation analysis. Another solution, robust and suitable for industry, is based on the observation of the keyhole inlet opening through a coaxial camera mounted in the welding head and the subsequent image processing by computer vision methods. A high-speed camera is used to understand the dynamics of the plasma plume. Through optical spectroscopy of the plume, we can study the excitation of elements in a material. It is also beneficial to monitor the gas flow of shielding gas using schlieren method.","PeriodicalId":112965,"journal":{"name":"Optical Angular Momentum","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115953487","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}
Applications, which can profit from holographic 3D displays, are the visualization of 3D data, computer-integrated manufacturing, 3D teleconferencing and mobile infotainment. However, one problem of holographic 3D displays, which are e.g. based on space bandwidth limited reconstruction of wave segments, is to realize a small form factor. Another problem is to provide a reasonable large volume for the user placement, which means to provide an acceptable freedom of movement. Both problems should be solved without decreasing the image quality of virtual and real object points, which are generated within the 3D display volume. A diffractive optical design using thick hologram gratings, which can be referred to as Bragg diffraction based volume gratings, can provide a small form factor and high definition natural viewing experience of 3D objects. A large collimated wave can be provided by an anamorphic backlight unit. The complex valued spatial light modulator add local curvatures to the wave field he is illuminated with. The modulated wave field is focused onto to the user plane by using a volume grating based field lens. Active type liquid crystal gratings provide 1D fine tracking of approximately ± 8° deg. Diffractive multiplex has to be implemented for each color and for a set of focus functions providing coarse tracking. Boundary conditions of the diffractive multiplexing are explained. This is done in regards to the display layout and by using the coupled wave theory (CWT). Aspects of diffractive cross talk and its suppression will be discussed including longitudinal apodized volume gratings.
{"title":"Field lens multiplexing in holographic 3D displays by using Bragg diffraction based volume gratings","authors":"G. Fütterer","doi":"10.1117/12.2257312","DOIUrl":"https://doi.org/10.1117/12.2257312","url":null,"abstract":"Applications, which can profit from holographic 3D displays, are the visualization of 3D data, computer-integrated manufacturing, 3D teleconferencing and mobile infotainment. However, one problem of holographic 3D displays, which are e.g. based on space bandwidth limited reconstruction of wave segments, is to realize a small form factor. Another problem is to provide a reasonable large volume for the user placement, which means to provide an acceptable freedom of movement. Both problems should be solved without decreasing the image quality of virtual and real object points, which are generated within the 3D display volume. A diffractive optical design using thick hologram gratings, which can be referred to as Bragg diffraction based volume gratings, can provide a small form factor and high definition natural viewing experience of 3D objects. A large collimated wave can be provided by an anamorphic backlight unit. The complex valued spatial light modulator add local curvatures to the wave field he is illuminated with. The modulated wave field is focused onto to the user plane by using a volume grating based field lens. Active type liquid crystal gratings provide 1D fine tracking of approximately ± 8° deg. Diffractive multiplex has to be implemented for each color and for a set of focus functions providing coarse tracking. Boundary conditions of the diffractive multiplexing are explained. This is done in regards to the display layout and by using the coupled wave theory (CWT). Aspects of diffractive cross talk and its suppression will be discussed including longitudinal apodized volume gratings.","PeriodicalId":112965,"journal":{"name":"Optical Angular Momentum","volume":"332 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115976059","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 mirrors have become an important tool in high power laser physics due to their ability to suppress laser pre-pulses and amplified spontaneous emission allowing a cleaner and sharper rising edge pulse to be focused onto a target. A PMMA ellipsoidal plasma mirror used to increase the peak intensity of a high power laser pulses before it reaches the target is presented. The ellipse has been designed to increase by a factor 3, between input and output, the F-number of the beam, inducing in theory a factor 9 gain in peak intensity. Diamond machining, which is a technique capable of producing sub-micron accuracy on steep, freeform surfaces, is an ideal process for manufacturing these types of mirrors. In this paper, we discuss the diamond machining requirements to manufacture such near diffraction limited high numerical aperture mirrors.
{"title":"Diamond machining of a single shot ellipsoidal focusing plasma mirror","authors":"C. Bourgenot, D. Crosby, D. Robertson","doi":"10.1117/12.2257414","DOIUrl":"https://doi.org/10.1117/12.2257414","url":null,"abstract":"Plasma mirrors have become an important tool in high power laser physics due to their ability to suppress laser pre-pulses and amplified spontaneous emission allowing a cleaner and sharper rising edge pulse to be focused onto a target. A PMMA ellipsoidal plasma mirror used to increase the peak intensity of a high power laser pulses before it reaches the target is presented. The ellipse has been designed to increase by a factor 3, between input and output, the F-number of the beam, inducing in theory a factor 9 gain in peak intensity. Diamond machining, which is a technique capable of producing sub-micron accuracy on steep, freeform surfaces, is an ideal process for manufacturing these types of mirrors. In this paper, we discuss the diamond machining requirements to manufacture such near diffraction limited high numerical aperture mirrors.","PeriodicalId":112965,"journal":{"name":"Optical Angular Momentum","volume":"10151 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129913006","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 paper presents analysis of the wavefront deformations of the optical waves transmitted through the ferroelectric single crystals with particular types of domain patterns by means of the numerical simulations. It is known that domain patterns influence the macroscopic properties of ferroelectric polydomain single crystals to a great extent. It is known that the domain spacing in ferroelectric single crystals can span the range from few tenths of nanometers to centimeters. Finally, it is known that measurements of the wavefront deformation can serve as input data for tomographic methods. In this paper, we perform exact numerical computations of the wavefront deformations of the optical wave passing through the ferroelectric domain patterns for different wavelengths. The considered simulations methods are based on solving the wave equation for the electromagnetic field. The computed numerical results are compared with simple analytical estimates. The key result of the paper is the benchmark of the limits for the three-dimensional observations of the ferroelectric domain patterns using digital holographic tomography.
{"title":"Multi-wavelength simulations of the wavefront deformation of the optical wave passing through the domain patterns in ferroelectric single crystals","authors":"K. Steiger, P. Mokry","doi":"10.1117/12.2257329","DOIUrl":"https://doi.org/10.1117/12.2257329","url":null,"abstract":"The paper presents analysis of the wavefront deformations of the optical waves transmitted through the ferroelectric single crystals with particular types of domain patterns by means of the numerical simulations. It is known that domain patterns influence the macroscopic properties of ferroelectric polydomain single crystals to a great extent. It is known that the domain spacing in ferroelectric single crystals can span the range from few tenths of nanometers to centimeters. Finally, it is known that measurements of the wavefront deformation can serve as input data for tomographic methods. In this paper, we perform exact numerical computations of the wavefront deformations of the optical wave passing through the ferroelectric domain patterns for different wavelengths. The considered simulations methods are based on solving the wave equation for the electromagnetic field. The computed numerical results are compared with simple analytical estimates. The key result of the paper is the benchmark of the limits for the three-dimensional observations of the ferroelectric domain patterns using digital holographic tomography.","PeriodicalId":112965,"journal":{"name":"Optical Angular Momentum","volume":"82 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122077123","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 digital holographic interferometry (DHI) for 3D measurement of temperature distributions in moving fluid is presented in this paper. The measurement uses digital holographic setup for measurement of a flow of fluid propagated through an orifice and tomographic approach for 3D reconstruction of the flow. The periodic character of the flow and synchronization between the digital camera and external trigger driving the phenomenon allows us to measure phenomena with much higher frequency when compared to frame rate of the digital camera. Furthermore one can capture a large number of the flow projections from different viewing directions which are later used for 3D tomographic reconstruction of the whole temperature field of the flow. The measurement results are verified and compared with hot wire method (CTA) in the paper.
{"title":"Heat and mass transfer measurement using method of digital holographic tomography","authors":"R. Dolecek, P. Psota, V. Ledl, T. Vít","doi":"10.1117/12.2257476","DOIUrl":"https://doi.org/10.1117/12.2257476","url":null,"abstract":"A digital holographic interferometry (DHI) for 3D measurement of temperature distributions in moving fluid is presented in this paper. The measurement uses digital holographic setup for measurement of a flow of fluid propagated through an orifice and tomographic approach for 3D reconstruction of the flow. The periodic character of the flow and synchronization between the digital camera and external trigger driving the phenomenon allows us to measure phenomena with much higher frequency when compared to frame rate of the digital camera. Furthermore one can capture a large number of the flow projections from different viewing directions which are later used for 3D tomographic reconstruction of the whole temperature field of the flow. The measurement results are verified and compared with hot wire method (CTA) in the paper.","PeriodicalId":112965,"journal":{"name":"Optical Angular Momentum","volume":"54 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121481669","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}
C. Supranowitz, J. Lormeau, C. Maloney, P. Murphy, P. Dumas
As applications for freeform optics continue to grow, the need for high-precision metrology is becoming more of a necessity. Currently, coordinate measuring machines (CMM) that implement touch probes or optical probes can measure the widest ranges of shapes of freeform optics, but these measurement solutions often lack sufficient lateral resolution and accuracy. Subaperture stitching interferometry (SSI™) extends traditional Fizeau interferometry to provide accurate, high-resolution measurements of flats, spheres, and aspheres, and development is currently on-going to enable measurements of freeform surfaces. We will present recent freeform metrology results, including repeatability and cross-test data. We will also present MRF® polishing results where the stitched data was used as the input “hitmap” to the deterministic polishing process.
{"title":"Freeform metrology using subaperture stitching interferometry","authors":"C. Supranowitz, J. Lormeau, C. Maloney, P. Murphy, P. Dumas","doi":"10.1117/12.2257279","DOIUrl":"https://doi.org/10.1117/12.2257279","url":null,"abstract":"As applications for freeform optics continue to grow, the need for high-precision metrology is becoming more of a necessity. Currently, coordinate measuring machines (CMM) that implement touch probes or optical probes can measure the widest ranges of shapes of freeform optics, but these measurement solutions often lack sufficient lateral resolution and accuracy. Subaperture stitching interferometry (SSI™) extends traditional Fizeau interferometry to provide accurate, high-resolution measurements of flats, spheres, and aspheres, and development is currently on-going to enable measurements of freeform surfaces. We will present recent freeform metrology results, including repeatability and cross-test data. We will also present MRF® polishing results where the stitched data was used as the input “hitmap” to the deterministic polishing process.","PeriodicalId":112965,"journal":{"name":"Optical Angular Momentum","volume":"71 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127376021","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 process of ultrasonic machining is especially used for brittle hard materials as the additional ultrasonic vibration of the tool at high frequencies and low amplitudes acts like a hammer on the surface. With this technology it is possible to drill holes with lower forces, therefor the machining can be done faster and the worktime is much less than conventionally. A three-axis dynamometer was used to measure the forces, which act between the tool and the sample part. A focus is set on the sharpness of the tool. The results of a test series are based on the Sauer Ultrasonic Grinding Centre. On the same machine it is possible to drill holes in the conventional way. Additional to the ultasonic Input the type an concentration of coolant is important for the Drilling-force. In the test there were three different coolant and three different concentrations tested. The combination of ultrasonic vibration and the right coolant and concentration is the best way to reduce the Forces. Another positive effect is, that lower drilling-forces produce smaller chipping on the edge of the hole. The way to reduce the forces and chipping is the main issue of this paper.
{"title":"Reducing forces during drilling brittle hard materials by using ultrasonic and variation of coolant","authors":"C. Schopf, R. Rascher","doi":"10.1117/12.2257106","DOIUrl":"https://doi.org/10.1117/12.2257106","url":null,"abstract":"The process of ultrasonic machining is especially used for brittle hard materials as the additional ultrasonic vibration of the tool at high frequencies and low amplitudes acts like a hammer on the surface. With this technology it is possible to drill holes with lower forces, therefor the machining can be done faster and the worktime is much less than conventionally. A three-axis dynamometer was used to measure the forces, which act between the tool and the sample part. A focus is set on the sharpness of the tool. The results of a test series are based on the Sauer Ultrasonic Grinding Centre. On the same machine it is possible to drill holes in the conventional way. Additional to the ultasonic Input the type an concentration of coolant is important for the Drilling-force. In the test there were three different coolant and three different concentrations tested. The combination of ultrasonic vibration and the right coolant and concentration is the best way to reduce the Forces. Another positive effect is, that lower drilling-forces produce smaller chipping on the edge of the hole. The way to reduce the forces and chipping is the main issue of this paper.","PeriodicalId":112965,"journal":{"name":"Optical Angular Momentum","volume":"21 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125684192","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. Melich, F. Procháska, D. Tomka, Z. Rail, J. Bartoníček, J. Plestil, Bohdan Šrajer
The paper describes an achromatic Steinhal type doublet that employs an aspherical surface to allow wide angle imaging. A design criteria, optimization techniques and tolerancing of the doublet are described. Further a manufacturing process of the system and achieved optical performance measurement is discussed. Benefits of the wide angle imaging doublet are recently planned to be used in automotive industry application, namely for optimizing of head-light performance and their final evaluation. The final device is planned to be part of the production line.
{"title":"Design, manufacturing, performance and application of wide angle aspherical achromatic doublet","authors":"R. Melich, F. Procháska, D. Tomka, Z. Rail, J. Bartoníček, J. Plestil, Bohdan Šrajer","doi":"10.1117/12.2257511","DOIUrl":"https://doi.org/10.1117/12.2257511","url":null,"abstract":"The paper describes an achromatic Steinhal type doublet that employs an aspherical surface to allow wide angle imaging. A design criteria, optimization techniques and tolerancing of the doublet are described. Further a manufacturing process of the system and achieved optical performance measurement is discussed. Benefits of the wide angle imaging doublet are recently planned to be used in automotive industry application, namely for optimizing of head-light performance and their final evaluation. The final device is planned to be part of the production line.","PeriodicalId":112965,"journal":{"name":"Optical Angular Momentum","volume":"63 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114612989","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 8-inch Clark objective lens of the Astronomical Institute of the Czech Academy of Sciences is probably the oldest doublet used for professional astronomical observation in the Czech Republic. Its optical imaging performance has become legendary among several generations of professional astronomers. The lens was manufactured by Alvan Clark in Cambridge, Massachusetts at the end of the 1850s. The 8-inch refractor functioned as the main telescope of the astronomical observatory in Ondřejov in the first half of the twentieth century. The objective has been cleaned and restored twice in the TOPTEC Centre in Turnov. We had the opportunity to measure the optical parameters of the doublet during its time in Turnov and we subsequently evaluated its residual aberrations. This paper is a record of the results of the optical simulations.
{"title":"The simulation of residual optical aberrations of the 8-inch Clark objective of the astronomical observatory in Ondřejov","authors":"Z. Rail, P. Pintr, Bohdan Šrajer","doi":"10.1117/12.2256660","DOIUrl":"https://doi.org/10.1117/12.2256660","url":null,"abstract":"The 8-inch Clark objective lens of the Astronomical Institute of the Czech Academy of Sciences is probably the oldest doublet used for professional astronomical observation in the Czech Republic. Its optical imaging performance has become legendary among several generations of professional astronomers. The lens was manufactured by Alvan Clark in Cambridge, Massachusetts at the end of the 1850s. The 8-inch refractor functioned as the main telescope of the astronomical observatory in Ondřejov in the first half of the twentieth century. The objective has been cleaned and restored twice in the TOPTEC Centre in Turnov. We had the opportunity to measure the optical parameters of the doublet during its time in Turnov and we subsequently evaluated its residual aberrations. This paper is a record of the results of the optical simulations.","PeriodicalId":112965,"journal":{"name":"Optical Angular Momentum","volume":"30 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2016-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132304219","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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