Thursday, November 15, 2012

Lasers in metrology

Lasers are widely used in metrology due to its unique high degree of monochromaticity. High monochromaticity yields clear interference fringes.  Low power He-Ne laser is preferred in metrological applications. In metrology, lasers are used in interferometry, holography and in scanning. Interferometry is a method used for the determination of distance by the proper measurement of wavelengths. Lasers are also used for machine tool calibration and alignment testing.  This method yields high accuracy and greater speeds. In a laser scanner, the object is mounted in a space between the laser source and a receiver. The receiver which contains a photo diode and a microprocessor computes dimension based on the shadow. Holography is a method based on interference and requires highly monochromatic light sources. Lasers are the automatic choice here. Holographic technique is widely used by automotive industry for the study of noise and vibration.

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