A pulse photobleaching methodology wherein a monochromatic illumination
(e.g., laser illumination) having a higher power intensity
(photobleaching power) just below the photodamage threshold of a
luminescent sample is initially used to significantly attenuate sample
luminescence without photothermally destroying the sample material.
Thereafter, the laser power density may be reduced to a significantly
lower level (analytical power level) to carry out spectroscopic
measurements (e.g., collection of Raman scattered photons) on the sample.
In one embodiment, the laser illumination wavelength remains the same
despite changes in laser power intensity. Some figures-of-merit may be
computed from optical measurements made at the analytical power level to
guide the photobleaching process. Sample-dependent combinations of laser
power density and short exposure times may be obtained to significantly
expedite photobleaching to assist in collection of sample spectral data
in the field without a long wait. Portable spectroscopy systems employing
pulse photobleaching may be devised for expeditious collection of
spectral data from luminescent samples in the field.