Telescopes with active cooling

Active cooling

— telescopes with active (forced) cooling systems, usually in the form of fans.

Only reflectors have the need for such cooling. For the normal operation of such a telescope, it is necessary that its parts, primarily the mirror, have the same temperature as the surrounding atmosphere. Otherwise, the air in contact with these parts (the so-called boundary layer) will heat up, which leads to the effect of "haze" and other image distortions. These phenomena are especially undesirable when observing deep space objects at high magnifications. The situation is aggravated by the fact that telescopes are most often stored in warm rooms, and used outside; at the same time, the temperature difference in the cold season can reach 30 °C or more, which is why the time for natural cooling is often calculated in hours.

In the light of all this, active cooling is sometimes simply indispensable: it allows you to significantly accelerate the equalization of temperatures. However, additional equipment inevitably affects the cost, and the fans require a power source to operate. In addition, active cooling is also available as separate devices that are purchased and installed as needed. Therefore, there are few telescopes originally equipped with this function nowadays — these are separate models on Dobson mounts, designed for viewing deep-sky objects and having rather large (as a result, long-cooling) lenses.