03.01.2015 Views

handbook of modern sensors

handbook of modern sensors

handbook of modern sensors

SHOW MORE
SHOW LESS

You also want an ePaper? Increase the reach of your titles

YUMPU automatically turns print PDFs into web optimized ePapers that Google loves.

4.3 Windows 133<br />

Fig. 4.7. Spherical window.<br />

Fig. 4.8. Spectral transmittance <strong>of</strong> a silicon window. Note that the majority <strong>of</strong> loss is due to a<br />

reflection from two surfaces.<br />

windows. Spectral transmittances <strong>of</strong> some materials are shown in Fig. 4.3. When<br />

selecting the material for a far-infrared window, the refractive index must be seriously<br />

considered because it determines the coefficient <strong>of</strong> reflectivity, absorptivity,<br />

and, eventually, transmittance. Figure 4.8 shows spectral transmittances <strong>of</strong> two silicon<br />

windows having different thicknesses. The total radiation (100%) at the window<br />

is divided into three portions: reflected (about 50% over the entire spectral range),

Hooray! Your file is uploaded and ready to be published.

Saved successfully!

Ooh no, something went wrong!