Using Microspectrometry to Examine Bird Feather Barbules

An important technique to analyze microscopic samples is UV-visible range microspectroscopy. The technique can analyze samples in the micron range, and as such is perfectly suitable for research on the spectral characteristics of microscopic components of bird feathers.

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Experiment

CRAIC Technologies’ 20/20 PV™ microspectrophotometer provides a fast, easy and non-destructive way to observe the microscopic features on bird features.

The 20/20 PV™ was configured for UV-visible-NIR reflectance spectroscopy for this series of experiments, with a permanently-calibrated variable aperture system. A 40x quartz objective and a 52x Schwarzschild-type objective were both used to compare and test their ability for imaging and spectroscopy in the UV, visible and NIR regions.

In these experiments, two feather samples were examined by reflectance microspectroscopy of their individual barbules. Each sample was examined at six different locations, first using the 40x quartz objective and later with the 52x Schwarzschild objective. Images and spectra from both objectives were acquired with a spectral range of 250 to 800 nm. The samples were prepared by just placing the feathers on a quartz slide and measuring their reflectance. As a reference, a sintered Teflon white standard was used.

Measurements

Shown below are selected microspectra. The sampling areas with the 40x objective and the 52x objective were 5.8 x 5.8 microns and 4.5 x 4.5 microns, respectively. This aperture size was sufficient to analyze the barbules of both feather samples.

Reflectance / Nanometers

Reflectance microspectra were acquired from individual barbules with the 40x objective. The blue feather image is shown on the left, while the bronze feather image is on the right. Both images were acquired with incident illumination. The black square is the measurement aperture that was used for the spectrometry.

Reflectance / Nanometers

The reflectance microspectra were acquired from individual barbules with the 52x objective. The blue feather image is shown on the left, while the bronze feather image is on the right. Both images were acquired with incident illumination. The black square is the measurement aperture that was used for the spectroscopy.

Results

A 40x Quartz and a 52x Schwarzschild objectives were compared for image quality and spectral results. It was observed that the image quality of the quartz objective was considerably superior at this magnification, while the spectral quality, for the spectral range covered, was quite similar to the Schwarzschild objective.

This information has been sourced, reviewed and adapted from materials provided by CRAIC Technologies.

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