3 Window Properties

The two main types of DMD windows are directly related to the packaging types:

• Type A DMD packaging uses Corning 7056 glass (typically about 3 mm thick).
• Wafer Level Packaging (WLP, often referred to as Sxxx package) uses Corning Eagle XG glass (typically about 1 mm thick or less).

Both the WLP window and the Type A window have an anti-reflective thin film coating to reduce reflections and increase transmission efficiency. Depending on the application, either the visible, UV, or NIR coating is used.

The values below describe a single pass of visible light (420 nm–680 nm) with random polarization through the window, and accounting for two surface coatings.

• Average transmittance, T_ave ≥ 99% at all angles 0–30° AOI,
• Average transmittance, T_ave ≥ 97% at all angles 30–45° AOI

All transmittance values are the total transmittance of the window (through both surfaces and glass). A transmission number of 96% is used in the Table 6-1 calculation representing a double pass through the window with approximately 99% transmission at each coated surface. See the DMD data sheets for device specific values.

For more information on window transmittance, see Wavelength Transmittance Considerations for DLP® DMD Window.