Test spectra from ¯uorescein collected in one shot and in a
few milliseconds show high accuracy and reproducibility. We
conclude from Fig. 2 that relative changes in ¯uorescence
intensity can be measured with an optimum accuracy of 3%,
whereas shifts in peak emission wavelength can be measured
with an accuracy better than 0.1 nm (see legend to Fig. 2b).
The accuracy of intensity measurements could be improved by
enclosing the apparatus in a chamber so as to minimize
turbulences around the sample. However, shifts in peak
wavelength are expected to be of more interest, being more
reproducible when the sample is changed since they are to a
large extent insensitive to the amount of probed material.