## Optics Dictionary

Sometimes reading a scientific explanation is as difficult as reading Parseltongue. This section features definitions and etymology for the terms and phrases you will encounter as you explore the science of light. Etymology is the study of the history of words — when they entered a language, from what source, and how their form and meaning have changed over time. Ever wonder how the word optics got its meaning? OK — probably not but now you can find out!

#### Ulbricht Sphere

General Terms

Also known as an Integrating sphere. A hollow sphere coated internally with a white diffusing material and openings for an incident beam, a specimen, and detector. The sphere is used to measuring the diffuse reflectance or transmittance of objects.

#### Ultraviolet (UV)

General Terms

Electromagnetic radiation with wavelengths shorter than visible light and longer than X-rays, and frequencies higher than visible light and less than X-rays. It has the range of wavelengths from 10 nm to 400 nm, where $1\text{\hspace{0.17em}}\text{nm}=1×{10}^{-9}\text{m}$ , and frequencies between , where 1 Hz (one hertz) is a one cycle per second.

#### Unpolarized light

General Terms

Light in which the electric field vector is oriented in a random, unpredictable fashion.