Laser interferometry
1002002-86
[DEFINITION]
A technique of detecting geometry, measuring accurate lengths and so
on by the interference of laser beam.
[DESCRIPTION]
By producing interference between beams that are reflected on the reference
plane and the objective plane, geometry of a static planar or spherical
object can be measured at a resolution of λ/2 or better (Wavelength λ of
a typical He-Ne laser is 0.633 μm). By combining interference technology
with electronics, the measuring resolution of geometry can be improved
up to about λ/100 while the resolution in measurement of lengths can be
improved even to λ/1000. Relative distance from a moving object can be
measured by the beat interference technique that exploits the Doppler effect
of laser beam, at a resolution of λ/4 or better. Vibrational displacements
can also be measured by the holography interference technique.
[References]
[Related Terms]