Term

Ulbricht Sphere

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.

Term

Ultraviolet (UV)

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 $1\text{nm}=1\times {10}^{-9}\text{m}$ , and frequencies between $0.75\times {10}^{15}\text{Hz to }30\times {10}^{15}\text{Hz}$ , where 1 Hz (one hertz) is a one cycle per second.

Term

Unpolarized light

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

To learn more about unpolarized light, click on the link to the Cross Polarization pamphlet.