Optical Characterization

Raman spectroscopy is a method of measuring frequencies and strengths of molecular vibrations. These frequencies typically belong in the infrared area of electromagnetic spectrum, but Raman spectroscopy allows measuring them using visible of near-IR light. Vibrational spectra of molecules are used to identify different species or crystalline structures of solids.


Thermo Scientific DXR3xi Raman Imaging Microscope

  • Excitation: 455 nm and 532 nm laser lines
  • Raman mapping: fast 3D positioning stage with 100-nm step sizes in the X-Y direction and 200-nm in the Z direction
  • Light detection: EMCCD camera
  • Spectral resolution: 2 to 5 cm-1, depending on the spectral window

Ellipsometry is used to infer information about thickness, permittivity and refractive index of thin films (down to ~nm).

J.A. Woollam RC2 Spectroscopic Ellipsometer: measurements of refractive indices, permittivities and Mueller matrices of bulk materials and thin films; composition, roughness and thickness of thin films, scatterometry and transmission,
210 – 2500 nm.

J.A. Woollam V-Vase Spectroscopic Ellipsometer: 200 – 3000 nm range, in air, temperature range of 80 – 1273 K

Grating spectrophotometry (PerkinElmer Lambda 950): capable of measuring transmittance, absorbance, reflectivity and scattered light spectra over a 190 – 3000 nm range, and is equipped with an integrating sphere for reflectivity and scattered light spectra measurements in various geometries.

Research Scientist in charge of Raman microscope, Woollam ellipsometers and Lambda 950: Alexei Lagoutchev

for access to the clean room optical microscopes listed below, please contact:
Ron Reger rreger@purdue.edu – (765) 494-6667

Digital 3D microscope (Keyence VHX-950F): 20x-2000x ; compound light with multiple lighting modes, image contour enhancement, glare removal, and vibration compensation. The depth composition feature produces sharp (focus-stacked) images and enables a full 3D reconstruction of the sample.

Optical microscopes (several, including Olympus BX-60 and Nikon Eclipse L150) offering 5x-150x lenses, bright/dark field and Nomarski, and CCDs with SPOT software for image capture.