why the mirror of a telescope need to be so heavy and thick ?
In: Engineering
The mirrors’ shape needs to be accurate to within a fraction of the wavelength of light. Just moving from a horizontal to a vertical position, as happens when pointing telescopes at different parts of the sky, puts varying stresses on a mirror which can cause it to flex out of shape. Mounting and supporting the mirror correctly helps but, even so, making it thick helps it keep its shape. These days the largest mirrors are honeycombed at the back to keep the weight down while maintaining the necessary thickness and rigidity.
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