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Horizontal Adaptive Optics in the Ground Layer Atmosphere

Håkansson, Nils LU (2010) In Lund Observatory Examensarbeten ASTM31 20101
Lund Observatory
Abstract
The usual terrestrial optical astronomy is focused on observing vertically through the atmosphere. When traveling through the atmosphere, the light coming from distant objects gets distorted by the turbulent atmosphere due to varying refractive indices. The effects varies with time and causes position shifts, size changes and intensity variations in an image. The closer to the ground that the light travels, the more distorted the image gets. For this thesis, the atmosphere was studied horizontally and close to the ground, thus the image gets greatly distorted. Using an adaptive optics setup to observe several light reflecting objects and several luminous objects at varying distances, the atmosphere is characterized by two parameters,... (More)
The usual terrestrial optical astronomy is focused on observing vertically through the atmosphere. When traveling through the atmosphere, the light coming from distant objects gets distorted by the turbulent atmosphere due to varying refractive indices. The effects varies with time and causes position shifts, size changes and intensity variations in an image. The closer to the ground that the light travels, the more distorted the image gets. For this thesis, the atmosphere was studied horizontally and close to the ground, thus the image gets greatly distorted. Using an adaptive optics setup to observe several light reflecting objects and several luminous objects at varying distances, the atmosphere is characterized by two parameters, coherence length (r0) and coherence time (t0). The image improvement by the system is also studied.
The atmospheric coherence length changes with distance, from an average of r0 = approx 5:1 cm at 70 m to r0 = approx 3 cm at 600 m. The system used works well at 70 meters if the coherence length is above about one or two centimeters, but at longer distances the system is not as successful. Several improvements to the system are finally suggested. (Less)
Please use this url to cite or link to this publication:
author
Håkansson, Nils LU
supervisor
organization
course
ASTM31 20101
year
type
H2 - Master's Degree (Two Years)
subject
publication/series
Lund Observatory Examensarbeten
report number
2010-EXA38
language
English
id
2173678
date added to LUP
2011-10-12 16:22:54
date last changed
2011-10-13 09:25:18
@misc{2173678,
  abstract     = {The usual terrestrial optical astronomy is focused on observing vertically through the atmosphere. When traveling through the atmosphere, the light coming from distant objects gets distorted by the turbulent atmosphere due to varying refractive indices. The effects varies with time and causes position shifts, size changes and intensity variations in an image. The closer to the ground that the light travels, the more distorted the image gets. For this thesis, the atmosphere was studied horizontally and close to the ground, thus the image gets greatly distorted. Using an adaptive optics setup to observe several light reflecting objects and several luminous objects at varying distances, the atmosphere is characterized by two parameters, coherence length (r0) and coherence time (t0). The image improvement by the system is also studied.
The atmospheric coherence length changes with distance, from an average of r0 = approx 5:1 cm at 70 m to r0 = approx 3 cm at 600 m. The system used works well at 70 meters if the coherence length is above about one or two centimeters, but at longer distances the system is not as successful. Several improvements to the system are finally suggested.},
  author       = {Håkansson, Nils},
  language     = {eng},
  note         = {Student Paper},
  series       = {Lund Observatory Examensarbeten},
  title        = {Horizontal Adaptive Optics in the Ground Layer Atmosphere},
  year         = {2010},
}