Measurement accuracies and measurement errors
PRIMES measuring instruments are designed for optimal performance and accuracy under industrial conditions. However a measurand still cannot be determined to any arbitrary accuracy nominated. It is also the case that achieving higher measurement accuracy is inevitably associated with more measurement effort and higher device costs.
For this reason there are frequently multiple measuring devices in the PRIMES portfolio for a measurand, for example laser power, reflecting this principle. The class of accuracy of a measuring device is firstly a result of the repeatability of the device itself and calibration tolerances.
For every measurand that can be measured with PRIMES measuring devices, PRIMES uses so-called working standard instruments in its calibration laboratory to calibrate the devices. These working standard instruments are calibrated regularly in a chain of calibrations against so-called reference standard instruments. The reference standard instrument is then calibrated annually at the national calibration facilities. For laser power, our reference standard instrument is calibrated at the German National Metrology Institute (PTB) against its National Power Standard instruments.
We are proud of the fact that the PTB itself uses a PRIMES EC-PM adapted to its purposes as a National Standard instrument for laser power.
There are no National Standard instruments for beam dimensions and beam propagation parameters. This type of calibration at PRIMES is based on our working standard instruments, which we derive internally from SI measurands according to the redundancy principle.
In the simplest scenario, in scanning systems for example, this can involve reference to the physical dimensions of apertures or fibre ends of a known diameter, or the feed of a linear axis by a known amount. For more complex scenarios, we have working standard instruments at our disposal in the form of measurement set-ups which also allow comparison between various measurement principles (mechanical scanning versus CCD). An important aspect of our work here is the redundancy principle, in other words validation not only by one process or measurand, but validation of measurands over a whole set of independent reference values and processes. This can only be achieved by a supplier who can offer a broad range of methods for beam analysis.
Along with the measurement accuracy of the device however, the conditions under which the measurement takes place have a considerable influence on the reliability of the readings. That is why we recommend adhering as closely as possible to the optimal conditions of use described in the operating manual.
Are you unsure about what measurement accuracy you can expect for your measurement task? Than get in touch with us. Our experts will work with you to produce an ideal measuring solution.