Baffle Positions

The baffles we will use for GEO600 will consist of a conical part (blue in the picture below) and a cylindrical part (light green) forming an angle of 25.7 degrees. The total width of a baffle is 14 cm, giving a height of about 3 cm. The surfaces of the baffle will be blackened with an commercial oxidizing stuff called Ebonol (from the japanese company: Enthone-Imasa, German representative: Enthone-Imasa Germany, 40699 Erkrath, Niermannsweg 3-5) to give sufficiently low back-scatter and reflection. The backscatter measured is about 0.1 -1% /sterad depending on the surface roughness of the stainless steel. A direct reflex is not detectable. The multiple reflections at the baffles' blackened surfaces, necessary for the light to return to the mirror will thus sufficiently reduce it's amplitude.

The baffles are spaced in such a way that no point of the wall can be seen from any point on any mirror's surface, hence all the light scattered by the mirrors is absorbed by the baffles. A safety margin allowing a slight sag of the tube between the suspension points is included. This gives a total number of 128 baffles per tube.

A Maple file for the calculation of the baffle positions.

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