I live in the north of France. During clear night of astronomy session after two hours out the corrector plate of my Meade LX200 14" is cover by dew. At that time it was impossible to go on observing and doing imaging.

The dew became rapidly a huge difficulty in so far as this problem occurred in different seasons with different levels of dew each time I went out.

Dew points indicate the amount moisture in the air. Dew point temperature is defined as the temperature to which the air would have to cool in order to reach saturation. A state of saturation remains when the air is holding the maximum amount of possible water vapor. Therefore, should the air cool, moisture will have to be removed from the air and this is accomplished through condensation.
This process results in the formation of tiny water droplets that can lead to the development of dew. To avoid such problem there are two solutions, which consist in either protecting the corrector or heating it. In order to find the right solution I searched and tested different possibilities on the web. In this Tech-Note section I describe these different existing possibilities from the first design to the final success.