Traceable spectral interferometry for length measurement

Abstract

Spectral interferometry is becoming a popular method of performing dimensional measurements, e.g. of surfaces, but such devices require pre-calibration of their spectrometers to achieve traceability. The use of a spectral lamp and imaging spectrometer to perform inherently traceable distance measurements using spectral interferometry, without the need for external calibration, is proposed and its experimental feasibility demonstrated. Initial experiments show measurements over a working range of 200 µm. The estimated standard uncertainty of the distance measurements is 0.6 nm, corresponding to an expanded uncertainty of 1.2nm at k = 2.

Editorial for the Metrologia Focus Issue on Length Metrology

“…Interferometry remains one of the most accurate techniques for performing dimensional metrology and it often benefits from a short traceability chain through direct links to the metre realisations as a wavelength of light. However, new research shows a divergence away from the classical fringe counting interferometer based on the popular monochromatic He-Ne laser, and use of the polychromatic spectral domain for the processing of interference signals [11] necessitating techniques and standards for calibration of the spectrometry [12].…”

Automatic raw material screening device for wind turbine foundation anchor bolt

“…In order to improve the screening efficiency, automatic bar screening should be completed in the transportation line of anchor raw materials, that is, the screening of anchor raw materials is completed during the movement of anchor raw materials. Because the anchor raw materials transmission is mostly completed by the V-wheel driven by the motor, there are multiple vibration sources [ 1 ] in the transmission process of the bolt raw material in the production line, such as motor vibration and uneven transmission line, resulting in vibration or slight jump of the bolt in the transmission process, which brings difficulties to the length measurement [ 2 ]. At the same time, in order to meet the needs of multi-task processing, the controller should have accurate length screening and task allocation functions.…”