The paper deals with the synthesis of band-limited functions that are generated by properly low-pass filtering a sequence of equally-spaced width-modulated unit-height pulses; simply choosing the pulse widths proportional to the corresponding sample values of the band-limited function to be generated, would result in an error. The exact relationship between the pulse widths and the corresponding sample values of the band-limited function to be synthesized, is derived. Error reduction can be achieved by using this relationship to calculate the pulse widths from the required sample values; in principle, a band-limited function can thus be realised to any degree of accuracy. It is shown which amount of error reduction can be obtained, when only a limited number of terms of the exact relationship is taken into account. The application to computer-generated half-tone transparencies is described.
{"title":"Error Reduction In Computer-Generated Half-Tone Transparencies That Are Based On Pulse-Width Modulation","authors":"M. J. Bastiaans","doi":"10.1117/12.941622","DOIUrl":"https://doi.org/10.1117/12.941622","url":null,"abstract":"The paper deals with the synthesis of band-limited functions that are generated by properly low-pass filtering a sequence of equally-spaced width-modulated unit-height pulses; simply choosing the pulse widths proportional to the corresponding sample values of the band-limited function to be generated, would result in an error. The exact relationship between the pulse widths and the corresponding sample values of the band-limited function to be synthesized, is derived. Error reduction can be achieved by using this relationship to calculate the pulse widths from the required sample values; in principle, a band-limited function can thus be realised to any degree of accuracy. It is shown which amount of error reduction can be obtained, when only a limited number of terms of the exact relationship is taken into account. The application to computer-generated half-tone transparencies is described.","PeriodicalId":127161,"journal":{"name":"Hague International Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1987-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128015314","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 paper an overview is given of the PCVD process as applied for the large scale production of optical fibres for telecommunication. The specific merits and potentials of the process, such as the profile independent high deposition rate and excellent controllability are discribed. The current state of the art of the process, as it is used in the Eindhoven production unit, is a deposition rate of 1 g/min., a preform size equivalent to 28 km of fibre and a drawing speed of 4 m/s. Fibre characteristics are well within the requirements imposed by the telecommunication market. The PCVD process has also proven to be suited for the production of dispersion flattened singlemode fibres and high NA graded index fibres for short distance applications. For both fibre types the high refractive index differences obtained with fluorine doping are exploited. Depending upon the market demands all fibre types can be manufactured at the same productivity. Some trends are given towards further increase of productivity and reduction of fibre costs.
{"title":"Production Of Optical Fibres For Telecommunication With The PCVD Process","authors":"Gerard Kuijt","doi":"10.1117/12.941594","DOIUrl":"https://doi.org/10.1117/12.941594","url":null,"abstract":"In this paper an overview is given of the PCVD process as applied for the large scale production of optical fibres for telecommunication. The specific merits and potentials of the process, such as the profile independent high deposition rate and excellent controllability are discribed. The current state of the art of the process, as it is used in the Eindhoven production unit, is a deposition rate of 1 g/min., a preform size equivalent to 28 km of fibre and a drawing speed of 4 m/s. Fibre characteristics are well within the requirements imposed by the telecommunication market. The PCVD process has also proven to be suited for the production of dispersion flattened singlemode fibres and high NA graded index fibres for short distance applications. For both fibre types the high refractive index differences obtained with fluorine doping are exploited. Depending upon the market demands all fibre types can be manufactured at the same productivity. Some trends are given towards further increase of productivity and reduction of fibre costs.","PeriodicalId":127161,"journal":{"name":"Hague International Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134314966","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 describe the possibility to use a single holographic optical element (HOE) for coupling between multimode optical fibers at a wavelength close to 1.3 μm. Dichromated gelatin is used as photosensitive medium for recording at 514 nm. Due to the large change of wavelength between recording and reconstruction of the FOE, the geometries of the experimental set up must be carefully choosen. First experimental results are presented, giving coupling losses of the device which is also designed to act as a wavelength division demultiplexer (for 4 different wavelengths centered on 1.3 μm, two consecutive wavelengths being separated by 30 nm).
{"title":"Holographic Optical Element Fiber Coupler For The Near Infrared","authors":"F. D. De Schryver","doi":"10.1117/12.941616","DOIUrl":"https://doi.org/10.1117/12.941616","url":null,"abstract":"We describe the possibility to use a single holographic optical element (HOE) for coupling between multimode optical fibers at a wavelength close to 1.3 μm. Dichromated gelatin is used as photosensitive medium for recording at 514 nm. Due to the large change of wavelength between recording and reconstruction of the FOE, the geometries of the experimental set up must be carefully choosen. First experimental results are presented, giving coupling losses of the device which is also designed to act as a wavelength division demultiplexer (for 4 different wavelengths centered on 1.3 μm, two consecutive wavelengths being separated by 30 nm).","PeriodicalId":127161,"journal":{"name":"Hague International Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126700635","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 objective lens is a single element glass lens with one aspheric replicated surface and one flat surface. The manufacture of the aspheric surface by means of replication is suitable for high quality mass-production.
物镜是具有一个非球面复制面和一个平面的单元件玻璃透镜。非球面的复制加工适用于高质量的批量生产。
{"title":"Mass-Production Of Diffraction Limited Replicated Objective Lenses For Compact-Disc Players.","authors":"Andrea Joop","doi":"10.1117/12.941592","DOIUrl":"https://doi.org/10.1117/12.941592","url":null,"abstract":"The objective lens is a single element glass lens with one aspheric replicated surface and one flat surface. The manufacture of the aspheric surface by means of replication is suitable for high quality mass-production.","PeriodicalId":127161,"journal":{"name":"Hague International Symposium","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133985270","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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