Definitions

Ratio of the molecular diffusion coefficients of momentum in terms of heat; used in convection studies.

The application of coherent wavefront techniques to the determination of the physical state of a system without appreciably altering that state.

Any testing method for materials and components that does not damage or destroy the test sample. Some of the methods used are x-ray, ultrasonic, electro-optic and magnetic testing.

The simplest method of transmission on a local area network. The entire bandwidth of the cable is used to transmit a single unmodulated digital signal. Baseband transmission is capable of...

The end of an optical fiber farthest from the source of illumination.

A small incandescent lamp whose intense beam is focused on the optical soundtrack of a motion picture film. The soundtrack modulates the beam, which in turn is detected by a photocell that produces...

Transparencies that represent progressive steps in the amount of transmitted radiation for administering predetermined amounts of radiation to a radiation-sensitive substance. The steps are...

In the SI system, prefix meaning one-thousandth, 10-3.

A unit of pressure, one-thousandth of a bar, equivalent to 100 Pascal and 0.75 torr. One atmosphere equals 1013 mbar.

A unit of metric measure equivalent to 1 thousandth (or 10-3 ) of the standard unit of optical power which is the diopter (1 millidiopter is 0.001 D). The power of a lens in millidiopters is the...

The fundamental wavelength standard of time or frequency. An atomic standard, it is properly expressed as 9,192,631,770 times the frequency of the transition between the hyperfine structure levels of...

The constant outward flow of weakly magnetized plasma from the sun that is deflected by the magnetic field of the earth and, flowing around the field, creates a magnetosphere.

That level of retinal illuminance resulting when a surface with a luminance of 1 candela/m2 is viewed through a pupil with an area of 1 mm2.