Electronic speckle pattern interferometry (ESPI), also known as TV Holography, is a technique which uses laser light, together with video detection, recording and processing to visualise static and dynamic displacements of components with optically rough surfaces. The visualisation is in the form of fringes on the image where each fringe normally represents a displacement of half a wavelength of the light used (i.e. quarter of a micrometre or so).
ESPI can be used for stress and strain measurement, vibration mode analysis and nondestructive testing.
ESPI is similar to holographic interferometry in many ways, but there are also significant differences between the two techniques.
Read more about Electronic Speckle Pattern Interferometry: How ESPI Works
Famous quotes containing the words electronic, speckle and/or pattern:
“The war was won on both sides: by the Vietnamese on the ground, by the Americans in the electronic mental space. And if the one side won an ideological and political victory, the other made Apocalypse Now and that has gone right around the world.”
—Jean Baudrillard (b. 1929)
“Leaves chase warm buses, speckle statued air,
Pile up in corners, fetch out vague broomed men
Through mists at morning.”
—Philip Larkin (1922–1986)
“Put out the light, and then put out the light.
If I quench thee, thou flaming minister,
I can again thy former light restore
Should I repent me; but once put out thy light,
Thou cunning’st pattern of excelling nature,
I know not where is that Promethean heat
That can thy light relume.”
—William Shakespeare (1564–1616)