Angle laboratory

About Us

Angle standard laboratory offers standards for angle measurement. Since 2010, the self calibration angle system (SelfA) has been established at our laboratory and acted as a primary national standard. This standard was launched under the corporation between NIMT and NIMJ by NEDO project.

Rotary Encoder

NIMT has developed the standard in the collaboration with National Metrology Institute of Japan, NIMJ) Since a rotary encoder provides high precision for angle measurement, the developed standard uses a combination of rotary encoders with self-calibration technique in order to establish a national primary angle standard in Thailand. The measuring range of 0-360 degrees with the accuracy of 0.15 arc second or 0.0000417 degrees.

Electronic Inclinometer

Electronic Inclinometer is widely used to measure a small angle. This instrument can be used with software for measuring flatness, straightness, squareness, and parallelism. In order to calibrate an electronic inclinometer, the autocollimator and the small angle generator are applied. The measuring range is ±1000 arc second with the accuracy of 2 µm/m or 0.4 arc second or 0.00012 degress approximately.


Autocollimator is an optical instrument which is precisely used to measure a small angle. In order to calibrate an autocollimator, We use the SelfA as a primary standard. The measuring range is ±1000 arc second with accuracy of 0.2 arc second or approximately of 0.000056 degrees. Additionally, the polygon mirrors are also calibrated by this system.

Electronic Inclinometer

Surface plate is used as a datum: therefore, the flatness of surface plate is important. Generally, a flatness of the surface plate is confirmed by Electronic Inclinometer which accuracy depends on standard usage and quality of the surface.