what is instrument calibration??

Question

due to my final project topic i need to know what calibration is?? hope u guys can help me out here ... thanks

Answer 1

*Purpose of instrument calibration :
Instrument calibration is intended to eliminate or reduce bias in an instrument's readings over a range for all continuous values. For this purpose, reference standards with known values for selected points covering the range of interest are measured with the instrument in question. Then a functional relationship is established between the values of the standards and the corresponding measurements. There are two basic situations.
*Instruments which require correction for bias :
The instrument reads in the same units as the reference standards. The purpose of the calibration is to identify and eliminate any bias in the instrument relative to the defined unit of measurement. For example, optical imaging systems that measure the width of lines on semiconductors read in micrometers, the unit of interest. Nonetheless, these instruments must be calibrated to values of reference standards if line width measurements across the industry are to agree with each other.

*Instruments whose measurements act as surrogates for other measurements :
The instrument reads in different units than the reference standards. The purpose of the calibration is to convert the instrument readings to the units of interest. An example is densitometer measurements that act as surrogates for measurements of radiation dosage. For this purpose, reference standards are irradiated at several dosage levels and then measured by radiometry. The same reference standards are measured by densitometer. The calibrated results of future densitometer readings on medical devices are the basis for deciding if the devices have been sterilized at the proper radiation level.

*Basic steps for correcting the instrument for bias :
The calibration method is the same for both situations and requires the following basic steps:
Selection of reference standards with known values to cover the range of interest.
Measurements on the reference standards with the instrument to be calibrated.
Functional relationship between the measured and known values of the reference standards (usually a least-squares fit to the data) called a calibration curve.
Correction of all measurements by the inverse of the calibration curve.

http://www.itl.nist.gov/div898/handbook/mpc/section3/mpc36.htm

Answer 2

Calibration is the process of causing an instrument to measure accurately, according to a standard measure. In other words, if a scale measures mass you want it to accurately read 10 kilograms, when in fact there are 10 kilograms on the scale. Likewise for a voltmeter, if there are 5.26 volts present to be measured, then you want the meter to read exactly 5.26 volts.

Generally, measuring instruments are "linear" instruments. If the physical quantity doubles, the reading doubles, so there is a linear gain associated with the instrument, and a 'zero' or offset associated with it, also (for most instruments the offset is zero). When you calibrate an instrument, what you usually do is to make sure the gain and offset are adjusted correctly.

Your bathroom scale has a 'zero' adjustment. When you adjust that knob to zero-out the scale, you are performing a type of calibration on the scale.

If you were weighing hand-filled 90# sacks of cement constantly on that scale, and if it showed 92# for a known exact 90# weight, you could calibrate the scale by adjusting the zero-knob so that it registered 90# when the 90# weight was placed on the scale. Then every 90# sack of cement could be accurately weighed on that scale.

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Answer 3

calibration is the act of adjusting an instrument, with the accuracy, with the precision of a known standard inclusive to the tolerance and repeatability of a certifiable tracable known standard.

Answer 4

I recently found out about this site about calibration of instruments and found the information fully detailed and very easy to understand. i'm sure it would be very helpful for you.

http://iamechatronics.com/notes/lessons-in-instrumentation/301-instrument-calibration

Answer 5

Calibration is fine tuning to specs be it musical or mechanics, Perfomance is key and calibration makes it happen.