सीएसआईआर-राष्ट्रीय भौतिक प्रयोगशाला

CSIR-National Physical Laboratory

Length Dimension & Nano Metrology


Iodine (127I2) Frequency Stablised He-Ne Laser: The Primary Standard

This section realizes and disseminates SI unit of length. Si unit of length is metre. The metre is defined as length of path travelled by light in vacuum in 1/ 299792458 of second. SI Unit metre is realized here using an iodine stabilized He-Ne Laser. Traceability to SI unit is disseminated over several orders of magnitude from micrometer to tens of metre.

The laboratory is equipped with state of art instruments like Gauge Block Interferometer, Displacement Measuring interferometer (for linear, angular, straightness and flatness of bed measurements), Flatness Measuring Interferometers for optical flats etc., Length Measuring Machine, Coordinate Measuring machines, Gauge Block Comparators, Autocollimators etc. traceable to SI. Dimensional measurements including, length, angle Form are carried out using these state-of-the-art equipment, good environmental control, and superior techniques.  Our efforts are focused on R and D in measurement techniques for industrial needs, reducing turnaround time of calibration services and a better service. Our Calibration measurements capabilities have been internationally peer reviewed and are available at:


The Standards of Dimension provides services to promote Global competitiveness in form of technical consultancy, measurement solutions, Calibration and testing services and trainings. It provides high accuracy measurements and follows international quality systems. Our services cover dimensional metrology needs over a large span. Our measurements results are highly valued by customers and a single measurement/ calibration service has high leverage in terms of metrology performed at Industries.

Dr. Girija Moona
Principal Scientist
Length Dimension and Nano Metrology
Apex Metrology Building, Room No. 15
National Physical Laboratory, New Delhi-110 012
Email: moonag@nplindia.org
Phone :+91 1145609490

Industry/ clients for India and abroad are  welcome to approach us for needs of measurements, training, consultancy services and  calibration. Dimensional Calibration Services For guidelines of calibration, please visit: Centre for Calibration & Testing (CFCT)

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