Driver's vision enhancer and DRS Technologies. All objects above Absolute zero (−273.15 °C / −459.67 °F) emit infrared radiation (IR), an invisible form of light beyond the optical spectrum. The optical spectrum is part of the electromagnetic energy spectrum which consists of ultraviolet, visible, and near, middle, and far-infrared energy. Only a small part of the optical spectrum is visible to the unaided eye. The Sun emits energy across the entire electromagnetic spectrum. Solar energy strikes the surface of objects. Some of that energy is absorbed and stored as heat (thermal energy). After sunset, this thermal energy remains and is emitted in the
Ultraviolet communication in butterflies rapid opening and closing of the wings, is performed when a male approaches another butterfly; yet, males copulate with females who perform this behavior, while retreating from males who perform the flutter response. By showing that male and female wings are similar in appearance except for UV reflectance and an approaching male is exposed to ultraviolet reflection of a male's wings during a flutter response, as well as ruling out temporal differences in the flutter behavior as a cause for sex recognition, Ronald Rutowski concluded that ultraviolet light was being used as an indicator of the male sex. However, in