Imaging properties of the GBT subreflector (1998) [1 citations — 1 self]
Download:
|
|
by Don Wells
Draft 20 Page 17 : 13 GBT Gregorian Focus Tracking in C GBT Memo 183.1 [Wel98d] Don
http://www.cv.nrao.edu/~dwells/srEllipsoidMemo.ps.gz
Add To MetaCart
Abstract:
The GBT Gregorian subreflector, an off-axis portion of an ellipsoid, images points in the neighborhood of its first focus onto points in the neighborhood of its second focus. Many of the pairs of points have identical separations, so that nearly-stigmatic imaging (nearly maximum gain) can be obtained for a variety of tilts and displacements of the subreflector. A grid of cases have been computed by ray tracing, and the results have been fitted with polynomials which are expressed in C. It is shown that, for imaging between points away from the foci, minimum phase error (maximum gain) will be obtained if the off-axis ellipsoid is tilted slightly; the optimum tilt is computed by a function expressed in C.
Citations
| 1015 | The C Programming Language – Kernighan, Ritchie |
| 4 | User's Manual|GaussFit: A system for least squares and robust estimation. The University of Texas at Austin, 1.0-12/2/88 edition – Jeerys, Fitzpatrick, et al. - 1988 |
| 2 | GBT Gregorian focus tracking in C. GBT Memo [tbd], NRAO, [in preparation – Wells - 1998 |
| 1 | A diffraction analysis of the elliptical reflector. In-House Report RADC-TR-7842, Rome Air Development Center, Griffiss Air Force Base – Fante - 1978 |
| 1 | An analysis of the elliptical reflector – Fante - 1979 |
| 1 | A summary of the GBT optics design – Norrod, Srikanth - 1996 |
| 1 | Approaches to the GBT vibration problem. GBT Memo 161, NRAO – Wells - 1996 |
| 1 | The "ray" ray tracing package. GBT Memo 178, NRAO – Wells - 1998 |
