The base unit of length in the International System of Units (SI) is the metre which, since 1983, is defined by the General Conference of Weights and Measures as "The length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second". In accordance with the recommendation for the practical realization of the above definition of the International Committee of Weights and Measures, the Laboratory maintains the metre through the wavelength of the 633 nm radiation from an iodine-stabilized helium-neon laser. This wavelength, λ, is derived from the internationally agreed value for the frequency, f, of the radiation and the speed of light, c (299 792 458 m/s), by the relation λ= c/f.
The Laboratory can provide calibration services in the following areas:
- Laser frequency/wavelength Linear dimensions
- Complex geometry
- Plastic Film Thickness Gauge
- Various dimensional instruments
- Measurement is performed at 20 °C in accordance with international convention.
Mr. George Tang
Tel: +852 2829 4805