Fitting The Main Light Gathering Mirror
Removal of dummy mirror
This mirror is one of the last parts to be assembled and extreme care is needed when attaching it to the telescope. A dummy mirror has been fitted for some months and must be removed before being replaced by the real mirror.
The main mirror cell is another important part of the instrument, initially holding the dummy mirror, and finally the real mirror safely in place as the telescope is moved to point at various parts of the night sky.
The sequence of pictures shows the dummy mirror being removed and placed on a jig for use in the construction of other telescopes.
Once removed the next step is to carry the main mirror to the telescope and carefully position it in the mirror cell.
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The main mirror is a precision optical component. If you look carefully at the picture below you can see that its surface is highly reflective and that it is not flat. In fact the surface is slight ly curved.
The purpose of this curvature is to allow the mirror to reflect light from the stars to a point or focus where a digital camera is placed to take photographs.
You will notice the grey pads on the edge of the mirror. These are secured to the glass using special bonding material which is extremely strong. The mirror is held firmly in place using these pads connected to the lateral support actuators on the mirror cell by connecting arms.
Mirror cell assembly
You can see in the right hand diagram how the primary mirror is secured in the mirror cell. The connecting arms connect the lateral actuators to the pads on the side of the mirror to prevent movement.
As the telescope operates the mirror, which weighs over one tonne, tends to move sideways, unless the telescope is pointing directly upwards (zenith). This movement is controlled by the lateral actuators which pull and push the mirror keeping it in the correct position.
The pictures below show the main mirror being carefully lifted onto the mirror cell which itself is held in a jig close to the Liverpool Telescope.
This jig will then carry the mirror cell and main mirror into position under the telescope where it will then be secured to the botton end trusses. See the news item on 7th January - Faulkes Telescope under construction.
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