Window Coatings - Motorola Symbol MS4404 Integration Manual

Chemically Tempered Float Glass
Glass is a hard material which provides excellent scratch and abrasion resistance. However, unannealed glass is
brittle. Increasing flexibility strength with minimal optical distortion requires chemical tempering. Glass cannot be
ultrasonically welded and is difficult to cut into odd shapes.
Suggested Window Properties
Table 2-1
Property
Material
Spectral Transmission
Thickness
Wavefront Distortion (transmission)
Clear Aperture
Surface Quality
Coating

Window Coatings

Table 2-2 lists some exit window manufacturers and anti-reflection coaters.
Anti-Reflection Coatings
Apply an anti-reflection coating to the inside and/or outside of the window to significantly reduce the amount of light
reflected off the window, back into the imager engine. The coating can also improve the range of acceptable window
positions and minimize performance degradation due to signal loss as the light passes through the window. Using
anti-reflection coatings on both the inside and outside of the window is highly recommended.
Description
Clear cell-cast acrylic.
85% minimum from 640 to 690 nanometers.
0.059 ± 0.005
0.2 wavelengths peak-to-valley maximum over any
0.08 in. diameter within the clear aperture.
To extend to within 0.04 in. of the edges all around.
60-20 scratch/dig
Both sides to be anti-reflection coated to provide
0.5% max reflectivity (each side) from 640 to 690
nanometers at nominal window tilt angle. Coatings
must comply with the hardness adherence
requirements of MIL-M-13508.
Getting Started 2 - 5