of the effelsberg 100 m radio telescope - inaf · of the effelsberg 100 m radio telescope axel...
TRANSCRIPT
![Page 1: of the Effelsberg 100 m radio telescope - INAF · of the Effelsberg 100 m radio telescope Axel Nothnagel, Christoph Holst Institute of Geodesy and Geoinformation . University of Bonn](https://reader035.vdocuments.site/reader035/viewer/2022062601/5e20284bda5c46271921d89f/html5/thumbnails/1.jpg)
Terrestrial laser scanning of the main reflector of the Effelsberg 100 m radio telescope
Axel Nothnagel, Christoph Holst Institute of Geodesy and Geoinformation
University of Bonn
![Page 2: of the Effelsberg 100 m radio telescope - INAF · of the Effelsberg 100 m radio telescope Axel Nothnagel, Christoph Holst Institute of Geodesy and Geoinformation . University of Bonn](https://reader035.vdocuments.site/reader035/viewer/2022062601/5e20284bda5c46271921d89f/html5/thumbnails/2.jpg)
2
Motivation
• Geodesists are interested in gravitationally induced path length variations at different elevation angles
• Astronomers are interested in surface quality
Manufacterer‘s model at 70° elev., Courtesy N. Junkes
![Page 3: of the Effelsberg 100 m radio telescope - INAF · of the Effelsberg 100 m radio telescope Axel Nothnagel, Christoph Holst Institute of Geodesy and Geoinformation . University of Bonn](https://reader035.vdocuments.site/reader035/viewer/2022062601/5e20284bda5c46271921d89f/html5/thumbnails/3.jpg)
3
Principles of terrestrial laser scanners
N.B.: Size of footprint depends on angle of incidence 1/cos γ for γ = 70° factor of 3
Panorama scanner
![Page 4: of the Effelsberg 100 m radio telescope - INAF · of the Effelsberg 100 m radio telescope Axel Nothnagel, Christoph Holst Institute of Geodesy and Geoinformation . University of Bonn](https://reader035.vdocuments.site/reader035/viewer/2022062601/5e20284bda5c46271921d89f/html5/thumbnails/4.jpg)
4
Scanning of radio telescopes
![Page 5: of the Effelsberg 100 m radio telescope - INAF · of the Effelsberg 100 m radio telescope Axel Nothnagel, Christoph Holst Institute of Geodesy and Geoinformation . University of Bonn](https://reader035.vdocuments.site/reader035/viewer/2022062601/5e20284bda5c46271921d89f/html5/thumbnails/5.jpg)
5
Scanning project 2010
Leica HDS 6100 Terrestrial Laser Scanner − Scanning in 7 elevations: 90°, 75°, 60°, 45°, 30°, 15°, 7.5° − Duration: 30 Min per elevation angle − Spacial resolution: 8 mm x 8 mm (at distance of 50 m) − Ca. 370 Mio. points per Elevation = 1.11 x 109 observations − Point precision (s = 30 - 50m): 5 – 8 mm − Size of laser spot (foortprint)
− 9.6 mm/30 m − 14 mm/50 m
![Page 6: of the Effelsberg 100 m radio telescope - INAF · of the Effelsberg 100 m radio telescope Axel Nothnagel, Christoph Holst Institute of Geodesy and Geoinformation . University of Bonn](https://reader035.vdocuments.site/reader035/viewer/2022062601/5e20284bda5c46271921d89f/html5/thumbnails/6.jpg)
6
Scanning 2010
![Page 7: of the Effelsberg 100 m radio telescope - INAF · of the Effelsberg 100 m radio telescope Axel Nothnagel, Christoph Holst Institute of Geodesy and Geoinformation . University of Bonn](https://reader035.vdocuments.site/reader035/viewer/2022062601/5e20284bda5c46271921d89f/html5/thumbnails/7.jpg)
7
Data decimation
Constant angular increments lead to inhomogeneous point densities overweighting of central area lead to wrong estimates if deformations present in this area
Original point density
Homogeneous point density
![Page 8: of the Effelsberg 100 m radio telescope - INAF · of the Effelsberg 100 m radio telescope Axel Nothnagel, Christoph Holst Institute of Geodesy and Geoinformation . University of Bonn](https://reader035.vdocuments.site/reader035/viewer/2022062601/5e20284bda5c46271921d89f/html5/thumbnails/8.jpg)
8
Least squares adjustment
Parameters of rotation paraboloid
With transformations
Parameters of rotational paraboloid
• Outer 10m ring not used for parameter estimation (unreliable)
• Outlier elimination (distance threshold) • Adjustment with Gauß-Helmert-Model • Cluster,130 GB memory, 4 h per elevation
![Page 9: of the Effelsberg 100 m radio telescope - INAF · of the Effelsberg 100 m radio telescope Axel Nothnagel, Christoph Holst Institute of Geodesy and Geoinformation . University of Bonn](https://reader035.vdocuments.site/reader035/viewer/2022062601/5e20284bda5c46271921d89f/html5/thumbnails/9.jpg)
9
Focal length results
Reduced point density
Full point density
Empirical focus optimization
![Page 10: of the Effelsberg 100 m radio telescope - INAF · of the Effelsberg 100 m radio telescope Axel Nothnagel, Christoph Holst Institute of Geodesy and Geoinformation . University of Bonn](https://reader035.vdocuments.site/reader035/viewer/2022062601/5e20284bda5c46271921d89f/html5/thumbnails/10.jpg)
10
Individual data points
W = C - O 54 lines 1 pt/64 mm2
![Page 11: of the Effelsberg 100 m radio telescope - INAF · of the Effelsberg 100 m radio telescope Axel Nothnagel, Christoph Holst Institute of Geodesy and Geoinformation . University of Bonn](https://reader035.vdocuments.site/reader035/viewer/2022062601/5e20284bda5c46271921d89f/html5/thumbnails/11.jpg)
11
Micro surfaces
![Page 12: of the Effelsberg 100 m radio telescope - INAF · of the Effelsberg 100 m radio telescope Axel Nothnagel, Christoph Holst Institute of Geodesy and Geoinformation . University of Bonn](https://reader035.vdocuments.site/reader035/viewer/2022062601/5e20284bda5c46271921d89f/html5/thumbnails/12.jpg)
12
Spline approximations
![Page 13: of the Effelsberg 100 m radio telescope - INAF · of the Effelsberg 100 m radio telescope Axel Nothnagel, Christoph Holst Institute of Geodesy and Geoinformation . University of Bonn](https://reader035.vdocuments.site/reader035/viewer/2022062601/5e20284bda5c46271921d89f/html5/thumbnails/13.jpg)
13
Comparisons
Holography at 32° Courtesy A. Kraus
Scanning at 30°
![Page 14: of the Effelsberg 100 m radio telescope - INAF · of the Effelsberg 100 m radio telescope Axel Nothnagel, Christoph Holst Institute of Geodesy and Geoinformation . University of Bonn](https://reader035.vdocuments.site/reader035/viewer/2022062601/5e20284bda5c46271921d89f/html5/thumbnails/14.jpg)
14
2013 Scanning Project
Leica Scan Station P20 − Scanning in 7 elevations: 90°, 75°, 60°, 45°, 30°, 15°, 7.5° − Duration: 15 Min per elevation angle − Spacial resolution: 6 mm x 6 mm (at distance of 50 m) − Ca. 500 Mio. points per Elevation = 1.5 x 109 observations − Point precision (s = 30 - 50m): 2 – 4 mm − Size of laser spot (foortprint)
− 8,8 mm/30 m − 12.8 mm/50 m
![Page 15: of the Effelsberg 100 m radio telescope - INAF · of the Effelsberg 100 m radio telescope Axel Nothnagel, Christoph Holst Institute of Geodesy and Geoinformation . University of Bonn](https://reader035.vdocuments.site/reader035/viewer/2022062601/5e20284bda5c46271921d89f/html5/thumbnails/15.jpg)
15
Scanning after sunset
![Page 16: of the Effelsberg 100 m radio telescope - INAF · of the Effelsberg 100 m radio telescope Axel Nothnagel, Christoph Holst Institute of Geodesy and Geoinformation . University of Bonn](https://reader035.vdocuments.site/reader035/viewer/2022062601/5e20284bda5c46271921d89f/html5/thumbnails/16.jpg)
16
![Page 17: of the Effelsberg 100 m radio telescope - INAF · of the Effelsberg 100 m radio telescope Axel Nothnagel, Christoph Holst Institute of Geodesy and Geoinformation . University of Bonn](https://reader035.vdocuments.site/reader035/viewer/2022062601/5e20284bda5c46271921d89f/html5/thumbnails/17.jpg)
17
7.5° Elevation
![Page 18: of the Effelsberg 100 m radio telescope - INAF · of the Effelsberg 100 m radio telescope Axel Nothnagel, Christoph Holst Institute of Geodesy and Geoinformation . University of Bonn](https://reader035.vdocuments.site/reader035/viewer/2022062601/5e20284bda5c46271921d89f/html5/thumbnails/18.jpg)
18
Raw results
a) Scanner has instrumental errors
b) Estimation of form paramaters depends on data density
![Page 19: of the Effelsberg 100 m radio telescope - INAF · of the Effelsberg 100 m radio telescope Axel Nothnagel, Christoph Holst Institute of Geodesy and Geoinformation . University of Bonn](https://reader035.vdocuments.site/reader035/viewer/2022062601/5e20284bda5c46271921d89f/html5/thumbnails/19.jpg)
19
Results after calibrations
- Data density - Horizontal collimation
error - Trunnion axis error - Vertical index error - Eccentricities of
graduated circles - Eccentricities of axes
![Page 20: of the Effelsberg 100 m radio telescope - INAF · of the Effelsberg 100 m radio telescope Axel Nothnagel, Christoph Holst Institute of Geodesy and Geoinformation . University of Bonn](https://reader035.vdocuments.site/reader035/viewer/2022062601/5e20284bda5c46271921d89f/html5/thumbnails/20.jpg)
20
Focal lengths of 2010 and 2013
dashed = 2010, grey = 2013 raw, black = 2013 corrected
![Page 21: of the Effelsberg 100 m radio telescope - INAF · of the Effelsberg 100 m radio telescope Axel Nothnagel, Christoph Holst Institute of Geodesy and Geoinformation . University of Bonn](https://reader035.vdocuments.site/reader035/viewer/2022062601/5e20284bda5c46271921d89f/html5/thumbnails/21.jpg)
21
Reflectivity
![Page 22: of the Effelsberg 100 m radio telescope - INAF · of the Effelsberg 100 m radio telescope Axel Nothnagel, Christoph Holst Institute of Geodesy and Geoinformation . University of Bonn](https://reader035.vdocuments.site/reader035/viewer/2022062601/5e20284bda5c46271921d89f/html5/thumbnails/22.jpg)
22
Radial residuals I
![Page 23: of the Effelsberg 100 m radio telescope - INAF · of the Effelsberg 100 m radio telescope Axel Nothnagel, Christoph Holst Institute of Geodesy and Geoinformation . University of Bonn](https://reader035.vdocuments.site/reader035/viewer/2022062601/5e20284bda5c46271921d89f/html5/thumbnails/23.jpg)
23
Radial residuals II
![Page 24: of the Effelsberg 100 m radio telescope - INAF · of the Effelsberg 100 m radio telescope Axel Nothnagel, Christoph Holst Institute of Geodesy and Geoinformation . University of Bonn](https://reader035.vdocuments.site/reader035/viewer/2022062601/5e20284bda5c46271921d89f/html5/thumbnails/24.jpg)
24
Elev. 60°, Panel 800
![Page 25: of the Effelsberg 100 m radio telescope - INAF · of the Effelsberg 100 m radio telescope Axel Nothnagel, Christoph Holst Institute of Geodesy and Geoinformation . University of Bonn](https://reader035.vdocuments.site/reader035/viewer/2022062601/5e20284bda5c46271921d89f/html5/thumbnails/25.jpg)
25
Residuals at elevation 60°
Panel 60 Panel 800
![Page 26: of the Effelsberg 100 m radio telescope - INAF · of the Effelsberg 100 m radio telescope Axel Nothnagel, Christoph Holst Institute of Geodesy and Geoinformation . University of Bonn](https://reader035.vdocuments.site/reader035/viewer/2022062601/5e20284bda5c46271921d89f/html5/thumbnails/26.jpg)
26
Panel segmentation
![Page 27: of the Effelsberg 100 m radio telescope - INAF · of the Effelsberg 100 m radio telescope Axel Nothnagel, Christoph Holst Institute of Geodesy and Geoinformation . University of Bonn](https://reader035.vdocuments.site/reader035/viewer/2022062601/5e20284bda5c46271921d89f/html5/thumbnails/27.jpg)
27
Panels at 7.5° elevation
![Page 28: of the Effelsberg 100 m radio telescope - INAF · of the Effelsberg 100 m radio telescope Axel Nothnagel, Christoph Holst Institute of Geodesy and Geoinformation . University of Bonn](https://reader035.vdocuments.site/reader035/viewer/2022062601/5e20284bda5c46271921d89f/html5/thumbnails/28.jpg)
28
Panels at 7.5° elevation
![Page 29: of the Effelsberg 100 m radio telescope - INAF · of the Effelsberg 100 m radio telescope Axel Nothnagel, Christoph Holst Institute of Geodesy and Geoinformation . University of Bonn](https://reader035.vdocuments.site/reader035/viewer/2022062601/5e20284bda5c46271921d89f/html5/thumbnails/29.jpg)
29
Panels at 90° elevation
![Page 30: of the Effelsberg 100 m radio telescope - INAF · of the Effelsberg 100 m radio telescope Axel Nothnagel, Christoph Holst Institute of Geodesy and Geoinformation . University of Bonn](https://reader035.vdocuments.site/reader035/viewer/2022062601/5e20284bda5c46271921d89f/html5/thumbnails/30.jpg)
30
Summary and Conclusions
• Terrestrial laser scanning has potential for detecting telescope deformations
• Terrestrial laser scanners (TLS) have dominant systematic errors, which need to be calibrated/corrected for
• Position of TLS is important (near primary focus) • Data analysis for radio telescopes requires sophisticated
pre-processing steps