Dimension Measurements
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, co (299 792 458 m/s), by the relation λ= co/f.
Laser interferometer systems are now in widespread use in engineering metrology for the measurement of length, displacement and other dimensional quantities. Usually the measuring values of these systems are based on the wavelengths of the incorporated laser sources. Hence, in order to ensure that the high potential accuracy of these instruments is achieved, the values of their wavelengths in vacuum must be known.
The Laboratory can provide calibration service for the measurement of the wavelength of any laser having a nominal wavelength of 633 nm. Calibration is performed by comparing the wavelength of the laser under test with the wavelength of the standard iodine-stabilized helium- neon laser of the Laboratory.
The Laboratory can also provide calibration services for gauges, measuring instruments and machines used to check and/or measure length and geometrical parameters (e.g. flatness, parallelism, straightness and squareness). The Laboratory also provides services for measuring dimensions, geometrical parameters, surface texture, and roundness of most engineering components and artifacts.
The measured values will be quoted at 20 ¢J in accordance with international convention.
Calibration charges
| Fee in HK$ | |
|---|---|
| Angle gauge, one piece | $1500 |
| Per additional piece | $740 |
| Angle plate, box angle plate | $2970 |
| Bench centre | $2970 |
| Bench micrometer | $3960 |
| Bevel protractor | $2970 |
| Calliper checker (up to 300 mm) | $6850 |
| Calliper checker (up to 600 mm) | $8550 |
| Check master (up to 300 mm) | $7700 |
| Check master (up to 600 mm) | $9410 |
| Check master (up to 1000 mm) | $13680 |
| Clinometer, single face | $2970 |
| Per additional face | $740 |
| Comparator (external) |
$2970 |
| Cylindrical square | $2970 |
| Dial gauge, dial test indicator | $2650 |
| Electronic indicating level | $2970 |
| Engineers' steel rule (up to 5 intervals) |
$2970 |
| Per additional interval | $250 |
| Feeler gauge (up to 10 blades) | $1600 |
| Per additional blade | $150 |
| Gauge block (up to 5 pieces) | $1910 |
| Per additional piece | $410 |
| Gauge block accessories | $5210 |
| Height setting micrometer | $7910 |
| Inclinable table | $4210 |
| Laser wavelength | $5100 |
| Length bar accessories | $5210 |
| Measuring microscope | Upon Request |
| Micrometer head |
$2100 |
| Micrometer setting rod | $1500 |
| Per additional piece | $740 |
| Optical dividing head | $8650 |
| Optical flat, per working face | $1500 |
| Optical parallels, per set of 5 | $4210 |
| Optical projector U | Upon Request |
| Parallels, per pair | $2970 |
| Pin gauge (up to 10 pieces) | $1600 |
| Per additional piece | $170 |
| Plain gap gauge |
$2170 |
| Plain plug gauge, cylindrical setting standard, gear measuring cylinder and roller |
$2170 |
| Polygon (up to 4 sides) | $2170 |
| Per additional side | $540 |
| Precision line scale (up to 5 intervals) | $2970 |
| Per additional interval | $200 |
| Ring gauge | $2190 |
| Rotary table | $8650 |
| Rotary and inclinable table | $11140 |
| Spirit level | $2590 |
| Square, Engineers' try | $2370 |
| Squareness tester | $4850 |
| Steel ball (up to 12 balls) | $1970 |
| Per additional ball | $170 |
| Straightedge (up to 500 mm) | $2970 |
| (over 500 mm) | $5920 |
| Straightedge (toolmakers') (up to 500 mm) | $2100 |
| (over 500 mm) | $4210 |
| Surface plate | $7030 |
| Surface texture standard | $1600 |
| Per additional sample | $850 |
| Toolmakers' flat | $1970 |
| Vee block (double vee), per pair | $3960 |
| Vee block (single vee), per pair | $2970 |
| Vernier height gauge | $2970 |
| Vernier depth gauge |
$2100 |
Enquiry Telephone: (852) 2829 4805, (852) 2798 7347
e-mail: sywong@itc.gov.hk
