scholarly journals Down With Magnification: The Micron Marker Rules!

1998 ◽  
Vol 6 (6) ◽  
pp. 12-13
Author(s):  
Joe Geller
Keyword(s):  
Quality Control ◽  
National Physical Laboratory ◽  
Image Display ◽  
Sem Image ◽  
Si Units ◽  
Current Wave ◽  
Physical Laboratory ◽  
The Uk ◽  
Almost All ◽  
The U.S

With today's current wave of quality consciousness, our quality control people tell us we MUST calibrate our instruments using standards that are traceable to the national laboratories (NIST - National Institute of Standards and Technology in the U.S.,. NPL - National Physical Laboratory in the UK, and others). But, is it really magnification that should be calibrated?While recently walking around the exhibit floor at the Microscopy & Micrcanalysis ‘98 Conference, I noticed the large SEM image display screens that now present our highly magnified specimens. Almost all vividly show a micron (using SI units this should be a “micrometer”) marker as well as the magnification. No doubt the accuracy is within the ± 3% that is commonly quoted by the manufacturers.

scholarly journals Establishment of air piston gauge as primary pressure standard at CSIR-National Physical Laboratory INDIA

ACTA IMEKO ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 329
Author(s):  
Vikas N. Thakur ◽  
Sanjay Yadav ◽  
Ashok Kumar
Keyword(s):  
Primary Standard ◽  
Effective Area ◽  
National Physical Laboratory ◽  
Area Measurement ◽  
Internal Diameter ◽  
Piston Cylinder ◽  
Piston Gauge ◽  
Si Units ◽  
Physical Laboratory ◽  
Pressure Standard

The air piston gauge (APG) was established at CSIR-National Physical Laboratory, India (NPLI) since 2000. Later the same piston- cylinder(p-c) assembly was calibrated in NIST USA; however, it was never published for metrology communities. As per international protocol, the establishment of the APG as a primary standard, the effective area of p-c assembly, and masses must be directly traceable to SI units. The first time we have calculated the effective area and associated uncertainty of p-c assembly using dimension and mass metrology, traceability to the SI units, i.e., meter and kilogram. To realize the APG as primary pressure standards, we have calculated the effective area of p-c assembly of APG directly from dimension metrology, which is further supported by various other methods. The effective area values obtained in the pressure range of 6.5 – 360 kPa lie in the range of 3.356729 – 3.357248 cm² due to uncertainty limitation in the measurement of dimension of internal diameter of cylinder. The expected values of the effective area which are also measured from cross-float technique against ultrasonic interferometer manometer (UIM), primary pressure standards. The accuracy in effective area measurement is possible only when the resolution in the internal radius of the cylinder should at least be up to 5th decimal order and the uncertainty is 80 nm. The expanded uncertainty was measured nearly 11 ppm at <em>k</em> = 2 by considering the uncertainty in internal radii of cylinder and radii of piston around 80 nm.

Accuracy and Linearity of Spectrophotometers in Clinical Chemistry Laboratories

1980 ◽  
Vol 17 (2) ◽  
pp. 87-90 ◽  
Author(s):  
John F Stevens
Keyword(s):  
Quality Control ◽  
United Kingdom ◽  
Clinical Chemistry ◽  
National Physical Laboratory ◽  
Cobalt Nitrate ◽  
The United Kingdom ◽  
Physical Laboratory ◽  
Wide Scatter ◽  
Chemistry Laboratories ◽  
Set Up

Solutions of cobalt nitrate sealed in vials were circulated to all clinical chemistry laboratories in the United Kingdom. Participants reported wavelengths of maximum absorbance together with the actual absorbances obtained. The results were compared with values obtained from the National Physical Laboratory. The results show a wide scatter, and several instruments were extensively repaired or replaced as a result of the survey. The most recently marketed machines had the best performance, and it is suggested that regular quality control and maintenance of the machines is vital. It is intended to set up a scheme for regular monitoring of spectrophotometer performance.

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