Abstract
A procedure for spectrophotometric statistical error calibration is described, in which estimates of the variance (sigma<sub>A</sub>2) in the absorbance A are derived as a function of A and the wavelength lambda, directly from recorded spectra. Spectra are obtained over the desired wavelength range for a number of neutral-density filters, and are then least-squares fitted piecemeal to low-order polynomials. The variances from these fits constitute the estimates of the instrumental variance sigma 2 for the lambda and A of the respective fitted segments. These values are in turn expressed as functions of lambda and A, by means of a small number of parameters. In the present case a representation in terms of A and I<sub>0</sub>, the 'effective' source intensity, is even more compact, requiring only five parameters to cover the 200-850nm region for absorbances up to and exceeding 2. For the instrument studied here, the high-A precision is limited by digitization error, the error being independent of lambda and I. Index Headings: UV-visible spectrophotometry; Statistical errors; Calibration; Least-squares weights; Spectral fitting.
PDF Article
More Like This
Cited By
You do not have subscription access to this journal. Cited by links are available to subscribers only. You may subscribe either as an Optica member, or as an authorized user of your institution.
Contact your librarian or system administrator
or
Login to access Optica Member Subscription