Single-layer AR coating

As just stated, two requirements need to be fulfilled for exact cancellation of reflected beams by a single-layer coating, i.e. the two reflections have to be out of phase by exactly tt, and exactly the same intensity is required. Consequently, a single-layer AR coating must be an odd number of quarter wavelengths to achieve the correct phase relation for wave cancellation. In addition, the refractive index of the thin-film medium has to obey the relation Mair < TF < S-... 

Figure 11.10 Dielectric coatings on optical substrates (a) single-layer AR-coating (b) quarter-quarter AR-coating (c) multilayer AR-coating (d) multilayer HR-coating. The refractive indices of the thin-film layer are larger than that for the substrate, /7h > > ns- For the layer thickness one has nL L = "h h = - o/A, where Xq is the design wavelength...

For a single-layer AR coating as shown in Figure 10.10, complete anti-reflection is attained when each optical parameter is under the following conditions ... 

Combining the effects of index of refraction and penetration depth of photons, the predicted CCD QE for a 15 m thick CCD with the Lesser backside passivation process and single layer Hf02 AR coating is presented in Fig.13. The sensitivity to thickness of AR coating and transparency of the CCD to longer wavelengths is very evident. 

Figure 4.59 Antireflection coatings, a Single layer Mgp2 on substrates with different refractive index b-d broadband multilayer AR-coatings, optimized for different spectral ranges...

Fig. 2.21 Experimental spectral reflection for single-layer ZnS AR coatings. 1 Ge substrate 2 mm without AR coating. 2 ZnS layer 1.2 pm deposited on the top surface of the Ge substrate 3 The same layer as in (2) deposited both on top and the bottom surface...

In addition to reflective or colored coatings, oxide coatings on glass and silicon substrates (single layers, multilayers, and porous layers) have been used extensively as antireflective (AR) surfaces in solar-related applications to improve device efficiency and as laser-damage-resistant AR coatings for laser optics, especially in inertial confinement fusion applications [25-37]. 

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