The Dimension Laboratory provides traceability to the international definition of the metre through a gauge block interferometer. This instrument, which uses two lasers calibrated by iodine-stabilized He-Ne laser, provides EMI with the capability of measuring various artifacts, either directly or indirectly, as listed below.
End Standards
According to ISO 3650, the reference grade gauge blocks (grade K) are calibrated by interferometry. With frequency stabilized lasers coupled to a Twyman-Green interferometer designed by the National Physical Laboratory, United Kingdom, the laboratory is able to provide the following services:
|
Gauge Length |
Material |
Parameter |
Calibration and Measurement Capability (CMC) |
|
0.5 mm to 100 mm |
Steel, Tungsten carbide and Ceramic |
Central length deviation |
Q[25 nm, 0.7×10-6 L] |
| 100 mm to 300 mm | Steel, Tungsten carbide and Ceramic | Central length deviation | Q[37 nm, 0.7×10-6 L] |
Gauge blocks of lower grades (grade 0, 1 and 2) are calibrated by comparison with EMI reference gauge blocks. Using this method, the following services are available:
|
Gauge Length |
Material |
Parameter |
CMC |
|
0.5 mm to 100 mm |
Steel |
Central length deviation |
Q[80 nm, 1.1×10-6 L] |
|
0.5 mm to 100 mm |
Ceramic |
Central length deviation |
Q[80 nm, 1.93×10-6 L] |
Diameter Standards
Diameter standards such as plug and ring gauges (including GO and NO-GO) are calibrated by comparative measurements using reference gauge blocks or reference ring gauges as standards by Universal Length Measuring Machine (ULM). In this category, the following services are provided by the laboratory:
|
Artifacts |
Range |
Parameter |
CMC |
|
Internal diameter gauges |
10 mm to 50 mm |
Diameter |
0.7 μm |
|
External diameter gauges |
1 to 80 mm |
Diameter |
0.8 μm |
By ULM, the following services can be provided by the laboratory:
|
Artifacts |
Range |
CMC |
|
Dial Gauges |
Up to 50 mm (resolution 0.001mm) |
2 μm |
| Dial Gauges | 50 mm to 100 mm (resolution 0.001mm) | 3 μm |
|
External micrometers (comparing with ceramic gauge block) |
0mm to 25 mm (resolution 0.001mm) |
2 μm |
|
External micrometers |
25mm to 75mm (resolution 0.001mm) |
2 μm |
|
External micrometers |
75mm to 175mm (resolution 0.001mm) |
3 μm |
|
Long gauge blocks |
125 mm to 500 mm |
Q[0.16 μm, 1.9×10-6 L |
Form
The following form parameters can be measured by the laboratory:
|
Artifacts |
Range |
CMC |
|
Optical flats and parallels (maximum diameter 50 mm) |
Flatness |
0.05 μm |
|
Universal Length Measuring machine (ULM) |
0 mm to 100 mm |
Q[0.062 μm, 1.3×10-6 L]
|
|
Gauge block comparator |
0.5 mm to 100 mm |
0.05 |
|
Angle indicating instruments |
Up to 90° (resolution 0.01°) |
0.02° |
|
Angle gauges |
Up to 90° |
0.6" |
|
Height gauges (analog and digital) |
Up to 600 mm (Resolution: 0.01 mm) |
(0.011 mm + 9×10-6 L)
|
|
Caliper (vernier and digital) |
Up to 600 mm (Resolution : 0.01 mm) |
(0.012 mm + 13×10-6 L)
|