Heat-insulating viewing window or viewing door for an apparatus having an interior temperature deviating from the ambient temperature thereof

A heat-insulating viewing window or door for an apparatus has an inner temperature in a cavity of the apparatus which deviates from the temperature of the ambient in which the apparatus operates. The viewing window is especially for cooking or baking ovens or dryers. The viewing window includes an arrangement of plates positioned at spacings from each other and held in a common frame. The plates can be made of glass, glass ceramic or another transparent temperature-resistant material. At least one further plate is mounted between the plate subjected to the ambient temperature and the plate subjected to the temperature of the interior cavity of the apparatus.