| Sub aperure and tube sock |
Sub-aperture mask and tube sock
Ola Karlsson and Johan Warell constructed the sub-aperture mask and the tube sock in the summer of 2005. The motivation for this was to increase the observation capability of the telescope into daytime observations, especially for observations of Mercury.
The sub-aperture mask consists of a square wooden plate, with four 30cm unobscured holes in it. In the middle there is a small "house", covering the focus machinery of the secondary mirror. The outside of the mask is painted in reflecting white, while the inside and holes are painted in dull black. The inside is also covered with black cloth to further reduce light reflections.
The mask is mounted in front of the telescope on wooden buffers with threaded bars going through them and attached with screws. The screws that attach the mask can be turned with hand power. Each sub-aperture hole can be covered with either a blocking plate or plates with even smaller apertures. These plates are screwed on to the aperture mask with screws that also can be turned by hand. There is also a possibility to attach diagonaly cut light buffer tubes in order to be able to observe closer to the sun.
In order to block out light coming from the side a tube sock was also made, in a blue, almost compleatly light tight fabric. The tube sock is attached to the base sides of the telescope and to the front side of the aperture mask with velcro stripes. Both the aperture mask and the tube sock can be mounted and dismounted by a single person in reasonable short time.
It is also possible to have only the tube sock mounted. This is done with a rope going in a "thunnel" close to the top end of the tube sock. The rope is tightened around the secondary mirror support ring.
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