= Raman microscope
{c}
= Raman microprobe
{c}
{synonym}
A \b[Raman microscope] combines an <optical microscope> with <Raman spectroscopy> to measure a spectrum from a localized specimen region. A <microscope objective> focuses a <laser> and collects scattered light; rejection filters suppress the intense excitation line, and a <spectrometer> separates the remaining wavelengths for detection. A facility instrument at the National University of Singapore supports both single-point measurements and <Raman mapping>.<Renishaw Raman Microscope by the National University of Singapore Department of Chemistry>[instrument description and measurement modes]{ref}
In a common backscattering arrangement, the same objective supplies excitation and collection. Moving the specimen or focus associates each <Raman spectrum> with a position, so a chosen spectral band can map chemical or structural variation. <Confocal microscopy> can additionally reject some out-of-focus light; a small map step by itself does not establish correspondingly fine <spatial resolution>.
For an original wavelength calculation, illuminate at $\lambda_0=532\,\mathrm{nm}$ and observe a Stokes <Raman shift> of $1000\,\mathrm{cm^{-1}}$. The scattered wavelength satisfies
$$
\frac1{\lambda_s}=\frac1{\lambda_0}-1000\,\mathrm{cm^{-1}},
\qquad \lambda_s\approx561.9\,\mathrm{nm}.
$$
Both reciprocal wavelengths must use the same length unit. The <spectrometer> measures the shifted light, while a filter suppresses the much brighter <Rayleigh scattering> near $532\,\mathrm{nm}$. <Spectral resolution> determines how nearby spectral features separate; objective focusing and the detection geometry determine spatial discrimination.
A concrete coupled apparatus placed a hydrated mouse bone in a mechanical tester mounted on a Raman microprobe stage. It followed mineral-band changes during elastic loading, connecting local molecular response with specimen mechanics.<Bone tissue ultrastructural response to elastic deformation probed by Raman spectroscopy by Michael D. Morris and others>[Abstract, custom tester, hydrated specimens and mineral-band observations]{ref} Interpreting such a measurement requires the specimen position, loading conditions and laser exposure to be controlled. Local heating, <fluorescence> and instrumental response can change a recorded spectrum; focused illumination is not automatically non-destructive.
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