James0Harris
30 M RADIO TELESCOPE
The Observatory is equipped with two radio telescopes (RT) – the only research capable RT in New Zealand - with dishes of size 12 m and 30 m in diameter. Both RT are of the Cassegrain system, using the main reflector (dish) and the sub-reflector which can be seeing on photos. Due to the larger structure of the 30 m RT, it is potentially vulnerable to gravity-induced structural deformation which varies as it operates at different elevation angles. Deviation from the ideal shape and misalignments between structural components can potentially result in partial loss of RT sensitivity. To study the surface quality of the main reflector, its alignment with the sub reflector, and the way these characteristics may vary, Recon Ltd was contracted to scan the surface of the telescope (the main and sub reflector) at different elevation angles.
Using a laser scanner for measuring surface quality is relatively new to Radio Astronomy and according to our knowledge has been used on very few occasions. Traditionally, two methods - Radio Frequency Holography and Photogrammetry - are widely used in radio astronomy. Both methods require specialised equipment, they are relatively time consuming, expensive and difficult to perform. The laser scanning method is easy and quick. Importantly, and unlike other methods, it allows scanning the main reflector and sub reflector surfaces jointly, therefore allowing to study the vital part of the RT “optics” as a whole. These advantages make the laser scanning heavily preferred over the other methods.
The FARO laser scanner is easy to carry and setup on the surface of the dish (weight ~5 kg). It has sufficient distance accuracy (± 1mm) and the operating range (from 0.6 m up to 320 m) for this research.
30 M RADIO TELESCOPE
The Observatory is equipped with two radio telescopes (RT) – the only research capable RT in New Zealand - with dishes of size 12 m and 30 m in diameter. Both RT are of the Cassegrain system, using the main reflector (dish) and the sub-reflector which can be seeing on photos. Due to the larger structure of the 30 m RT, it is potentially vulnerable to gravity-induced structural deformation which varies as it operates at different elevation angles. Deviation from the ideal shape and misalignments between structural components can potentially result in partial loss of RT sensitivity. To study the surface quality of the main reflector, its alignment with the sub reflector, and the way these characteristics may vary, Recon Ltd was contracted to scan the surface of the telescope (the main and sub reflector) at different elevation angles.
Using a laser scanner for measuring surface quality is relatively new to Radio Astronomy and according to our knowledge has been used on very few occasions. Traditionally, two methods - Radio Frequency Holography and Photogrammetry - are widely used in radio astronomy. Both methods require specialised equipment, they are relatively time consuming, expensive and difficult to perform. The laser scanning method is easy and quick. Importantly, and unlike other methods, it allows scanning the main reflector and sub reflector surfaces jointly, therefore allowing to study the vital part of the RT “optics” as a whole. These advantages make the laser scanning heavily preferred over the other methods.
The FARO laser scanner is easy to carry and setup on the surface of the dish (weight ~5 kg). It has sufficient distance accuracy (± 1mm) and the operating range (from 0.6 m up to 320 m) for this research.