Glossary - Part U

•  Ultra quick flash – The character of a light in which identical flashes are repeated at a rate of not less than 160 flashes per minute.

•  Ultraviolet Glass Damage: Fresnel lenses often have a rather pronounced yellow or amber color. The lenses were very clear with only a tiny yellow-green tinge when first manufactured, but, over time, sunlight also influenced the color of the glass.

•  Upper Catadioptric Prisms: Glass lens elements that are located above the dioptric sections of the lens assembly.