Daily Image
05-02-2016
A thin meniscus shaped parabolic mirror
| Submitter: | Rik ter Horst |
| Description: | Trapped heat inside an astronomical mirror deteriorates the image quality considerably. Sometimes cooling down takes hours, and only after being thermally stabilized image quality will be optimal, seeing permitted of course. A year ago I started making a 19 mm thin, 400 mm diameter F/3 meniscus mirror for my new Wide Field telescope. This was very challengeing, as such a thin mirror is almost a guarantee for astigmatism due to its relative flexibility, something you don't want. The glass was slumped into an F/3 radius in an oven, followed by grinding and polishing. Using a new technique I managed to rule out any astigmatism and after months of figuring my new telescope had its first light. The mirror cooled down within an hour (15 degrees) and performs very fine, so I'm very happy with the result of this experiment. The animation shows the mirror during a Foucault test at the centre of curvature, measuring several zones. |
| Copyright: | Rik ter Horst |
| Tweet |  |