The invention comprises a method of adapting derivative spectrometry for
use in a downhole environment and addresses problems that are inherent in
this environment. Such problems include, but are not limited to, elevated
temperatures and scattering from particles residing within dirty fluid
samples. The invention improves the resolution by measuring the first
derivative of the spectrum. The derivative spectrometer of this invention
operates by vibrating a linear variable interference filter back and forth
along the plane of the filter or by oscillating a circular variable filter
about some angle.
