Method of evaluating data quality

摘要

Methodology for determining uncertainty in a data set which characterizes a sample involving elimination of the influence of sample alteration drift caused by data set acquisition, and/or elimination of the influence of system drift during data acquisition.

主权项

1. A method of compensating a sample characterizing data set for sample and system drift during data acquisition, comprising the steps of:
a) providing a system comprising:
a source of a beam of electromagnetic radiation;a sample supporting stage;means for controlling where a beam of electromagnetic radiation from said source impinges on a sample placed on said stage; anda detector of electromagnetic radiation which exits said sample; b) in an alternating fashion practicing steps b1 and b2, each a plurality of times, to provide two data sets:
b1) a first data set being obtained by causing a beam of electromagnetic radiation to impinge on a first position on said sample so that it interacts therewith and enters said detector, so that said detector provides as output, a data point set over a time T1, which is the total time electromagnetic radiation interacts with said first position;b2) a second data set being obtained by causing said beam of electromagnetic radiation to impinge on a second position on said sample so that it interacts therewith and enters said detector, so that said detector provides a data point set over a time T2, which is the total time electromagnetic radiation interacts with said second position; c) defining first order changes for the data sets obtained in step b as:
DATA CHANGE1=SYSTEM DRIFT+SAMPLE DRIFT1; andDATA CHANGE2=SYSTEM DRIFT+SAMPLE DRIFT2;and therefrom determining:SAMPLE⁢⁢DRIFT⁢⁢2=(DATA⁢⁢CHANGE⁢⁢2-DAT⁢A⁢⁢CHANGE⁢⁢1)(1-R⁢⁢12); where R12=T1/T2;and:
SYSTEM DRIFT=DATA CHANGE2−SAMPLE DRIFT2; and SAMPLE DRIFT1=DATA CHANGE1−SYSTEM DRIFT;such that values for sample drift1, sample drift2 and system drift terms are determined from first order changes from said first and second data sets;said method further, optionally, comprising:
d) compensating at least one of the first and second data sets which correspond to the first and second positions on said sample for data acquisition system drift, sample drift or both;to the end that a sample characterizing data set which is compensated for sample and system drift during data acquisition is achieved.