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. Author manuscript; available in PMC: 2016 Sep 15.
Published in final edited form as: Acta Biomater. 2015 Jun 15;24:309–321. doi: 10.1016/j.actbio.2015.06.012

Figure 4.

Figure 4

Intensity and wavelength of the stop band reflected from smooth (solid circles) and roughened (open circles) porous Si rugate filter samples, as a function of angle relative to the surface normal. A specular reflection corresponds to 0 degrees from the surface normal. For this sample, roughening is achieved by spray-coating with a fine mist of micron-scale polymer droplets [40]. Inset shows the optical setup used, including the sample, lens, and bifurcated fiber optic cable. In this experiment the observation axis is coaxial with the illumination axis, the diameter of the light spot on the sample is 0.74 cm, and the sample-lens distance is 56.7 cm.