{"title":"电讯天线转换成射电望远镜:卡塞格伦天线光学和碟形表面质量的激光扫描测量","authors":"A. Rasha, T. Natusch, C. Granet, S. Gulyaev","doi":"10.1142/S2251171719500107","DOIUrl":null,"url":null,"abstract":"A number of countries have identified redundant large telecommunications antennas (TA) and indicated their intention to convert them into radio telescopes (RT). As the efficiency of a parabolic dish radio telescope depends on its surface quality and optical alignment, a careful assessment of these properties should be undertaken before conversion. Here, as a case study, we describe a laser scanning (LS) procedure we developed and used for the Warkworth 30[Formula: see text]m Cassegrain antenna. To investigate gravity-induced mechanical deformation of the antenna surfaces and structure, we conducted measurements at elevation angles ranging from 6 to 90 degrees. The ability of a laser scanner to survey its nominal [Formula: see text] steradian surroundings allows for simultaneous study of the main and subreflectors, readily permitting a dynamic investigation of variation of the telescope optics as elevation changes occur. In particular, the method we present here allows determination of the surface quality of both main and subreflectors, the displacement between centers of the reflectors, their relative rotations and focal length variation as a function of elevation angle. We discuss details of settings, measurements, data processing and analysis focusing on possible difficulties and pitfalls. In our case study, no significant elevation-dependent surface deformation of the reflectors was observed, with the overall standard deviation of the postfit residuals varying between 1.0 and 1.7[Formula: see text]mm as elevation angle changes from 90∘ to 6∘, respectively. We, therefore, conclude that in our case both the main reflector and the subreflector, as well as the telescope optics, remain unaffected by gravitational deformation within the accuracy of the measurements, a conclusion that can possibly be extended to the similar class of TA currently considered for conversion.","PeriodicalId":45132,"journal":{"name":"Journal of Astronomical Instrumentation","volume":null,"pages":null},"PeriodicalIF":1.5000,"publicationDate":"2019-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1142/S2251171719500107","citationCount":"1","resultStr":"{\"title\":\"Conversion of a Telecommunications Antenna into a Radio Telescope: Laser Scanner Measurements of Optics and Dish Surface Quality of a Cassegrain Antenna\",\"authors\":\"A. Rasha, T. Natusch, C. Granet, S. Gulyaev\",\"doi\":\"10.1142/S2251171719500107\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"A number of countries have identified redundant large telecommunications antennas (TA) and indicated their intention to convert them into radio telescopes (RT). As the efficiency of a parabolic dish radio telescope depends on its surface quality and optical alignment, a careful assessment of these properties should be undertaken before conversion. Here, as a case study, we describe a laser scanning (LS) procedure we developed and used for the Warkworth 30[Formula: see text]m Cassegrain antenna. To investigate gravity-induced mechanical deformation of the antenna surfaces and structure, we conducted measurements at elevation angles ranging from 6 to 90 degrees. The ability of a laser scanner to survey its nominal [Formula: see text] steradian surroundings allows for simultaneous study of the main and subreflectors, readily permitting a dynamic investigation of variation of the telescope optics as elevation changes occur. In particular, the method we present here allows determination of the surface quality of both main and subreflectors, the displacement between centers of the reflectors, their relative rotations and focal length variation as a function of elevation angle. We discuss details of settings, measurements, data processing and analysis focusing on possible difficulties and pitfalls. In our case study, no significant elevation-dependent surface deformation of the reflectors was observed, with the overall standard deviation of the postfit residuals varying between 1.0 and 1.7[Formula: see text]mm as elevation angle changes from 90∘ to 6∘, respectively. We, therefore, conclude that in our case both the main reflector and the subreflector, as well as the telescope optics, remain unaffected by gravitational deformation within the accuracy of the measurements, a conclusion that can possibly be extended to the similar class of TA currently considered for conversion.\",\"PeriodicalId\":45132,\"journal\":{\"name\":\"Journal of Astronomical Instrumentation\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":1.5000,\"publicationDate\":\"2019-09-10\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://sci-hub-pdf.com/10.1142/S2251171719500107\",\"citationCount\":\"1\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of Astronomical Instrumentation\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://doi.org/10.1142/S2251171719500107\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"ASTRONOMY & ASTROPHYSICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Astronomical Instrumentation","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1142/S2251171719500107","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"ASTRONOMY & ASTROPHYSICS","Score":null,"Total":0}
Conversion of a Telecommunications Antenna into a Radio Telescope: Laser Scanner Measurements of Optics and Dish Surface Quality of a Cassegrain Antenna
A number of countries have identified redundant large telecommunications antennas (TA) and indicated their intention to convert them into radio telescopes (RT). As the efficiency of a parabolic dish radio telescope depends on its surface quality and optical alignment, a careful assessment of these properties should be undertaken before conversion. Here, as a case study, we describe a laser scanning (LS) procedure we developed and used for the Warkworth 30[Formula: see text]m Cassegrain antenna. To investigate gravity-induced mechanical deformation of the antenna surfaces and structure, we conducted measurements at elevation angles ranging from 6 to 90 degrees. The ability of a laser scanner to survey its nominal [Formula: see text] steradian surroundings allows for simultaneous study of the main and subreflectors, readily permitting a dynamic investigation of variation of the telescope optics as elevation changes occur. In particular, the method we present here allows determination of the surface quality of both main and subreflectors, the displacement between centers of the reflectors, their relative rotations and focal length variation as a function of elevation angle. We discuss details of settings, measurements, data processing and analysis focusing on possible difficulties and pitfalls. In our case study, no significant elevation-dependent surface deformation of the reflectors was observed, with the overall standard deviation of the postfit residuals varying between 1.0 and 1.7[Formula: see text]mm as elevation angle changes from 90∘ to 6∘, respectively. We, therefore, conclude that in our case both the main reflector and the subreflector, as well as the telescope optics, remain unaffected by gravitational deformation within the accuracy of the measurements, a conclusion that can possibly be extended to the similar class of TA currently considered for conversion.
期刊介绍:
The Journal of Astronomical Instrumentation (JAI) publishes papers describing instruments and components being proposed, developed, under construction and in use. JAI also publishes papers that describe facility operations, lessons learned in design, construction, and operation, algorithms and their implementations, and techniques, including calibration, that are fundamental elements of instrumentation. The journal focuses on astronomical instrumentation topics in all wavebands (Radio to Gamma-Ray) and includes the disciplines of Heliophysics, Space Weather, Lunar and Planetary Science, Exoplanet Exploration, and Astroparticle Observation (cosmic rays, cosmic neutrinos, etc.). Concepts, designs, components, algorithms, integrated systems, operations, data archiving techniques and lessons learned applicable but not limited to the following platforms are pertinent to this journal. Example topics are listed below each platform, and it is recognized that many of these topics are relevant to multiple platforms. Relevant platforms include: Ground-based observatories[...] Stratospheric aircraft[...] Balloons and suborbital rockets[...] Space-based observatories and systems[...] Landers and rovers, and other planetary-based instrument concepts[...]