Precision scales, stage micrometers and graticules

Making traceable measurements

High quality calibration scales are required for making traceable measurements with non-contacting imaging and vision measurement systems. NPL designs and calibrates a range of optical scales and reference patterns for quantitative microscopy, image analysis and non-contact measurement systems.

Our extensive range of measurement facilities provides sub-micrometer accuracy for the following types of scales:

Stage micrometers

NPL provides a UKAS and CIPM-MRA- accredited service for the calibration of stage micrometers (and other linescales or calibration standards) up to 150 mm in length. Scales are measured using a microscope with a travelling stage. The displacement of the stage is measured by means of a helium-neon laser interferometer, providing an uncertainty of 0.2 µm for scale lengths up to 50 mm and 0.4 µm for scale lengths up to 150 mm, with direct traceability to the metre. The accredited capabilities for different scale length ranges are listed under the Service Reference code LR04 and found in the calibration and testing schedule issued by UKAS (laboratory No.0478). 

Optical dimensional standard

The NPL-designed Optical Dimensional Standard is a single high-precision calibration artefact, bearing a vast range of different scales/patterns designed to meet virtually all optical dimensional calibration needs where high precision calibration and verification of the imaging system is required. Optical instrumentation companies, vision machine and image analysis developers, system integrators and end users can all benefit from using the NPL Optical Dimensional Standard.

The Optical Dimensional Standard is a 100 mm square quartz or glass plate bearing many thousands of bright chrome structures ranging in sizes between 1 µm to 60 mm. There are twenty-two patterns, scaled and repeated on the glass six times, enabling it to be used at different magnifications. Additionally, there are six linear scales with nominal length of 60 mm and 49 targets that form the X-Y stage position calibration grid. 
 
 NPL provides a UKAS-accredited calibration service (laboratory No. 0478) for the calibration of linewidth patterns ranging from 1 µm to 50 µm on the Optical Dimensional Standard, with a measurement uncertainty of 0.05 μm for features ranging from 1 μm to 10 μm and 0.1 μm for features ranging from 10 μm to 50 μm.

Other patterns on this standard can also be measured using our wide range of instruments. Please contact us for further details.

Further information on the Optical Dimensional Standard and pattern dimensions 

Reference stage graticules

The NPL-designed Reference Stage Graticule is a calibration artefact which contains four test areas: 

• 400 µm square grid 
• 20 x 17 monosize array of 15 µm diameter spots
• Root-2 array of spots from 3 µm to 48 µm diameter, and 
• 10 x 10 log-normally distributed array of 100 spots ranging from 4.5 µm to 27 µm diameter.

It is ideally suited for calibrating image analyser systems and can also be used as a high precision stage micrometer. NPL provides a UKAS-accredited calibration service (laboratory No. 0478) for the calibration of patterns on the Reference Stage Graticule, listed under the Service Reference code LR07.

X-Y grid plates

We have developed range of non-contact dimensional standards designed to calibrate the co-planar axes of industrial imaging systems and vision inspection machines.

The standards are chrome on glass and have working areas from 250 mm x 250 mm to 650 mm x 650 mm. The chrome layer bears metrology structures composed of target dies, set on a square grid that has a nominal pitch of 25 mm. Each die is made up of chrome and clear circles, crosses and squares. The nominal external dimensions of these features start from 30 µm, with each successive feature being twice the size of the previous, up to 1 mm.

Don’t see what you are looking for? Our diverse skill set enables us to provide bespoke solutions. Please contact us to discuss your requirements.

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