Symbol SE 923, Integration Manual

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2-10
SE-923 Scan Engine Integration Guide
Commercially Available Coatings
Anti-Reflection Coatings
An anti-reflection coating can be applied to the inside and/or outside of the window, which
greatly reduces the amount of light reflected off the window, back into the scan engine. This
coating can increase the range of acceptable window positions and minimize performance
degradation due to signal loss as the light passes through the window.
Polysiloxane Coating
Polysiloxane type coatings are applied to plastic surfaces to improve the surface resistance to
both scratch and abrasion. They are generally applied by dipping and then allowed to air dry
in an oven with filtered hot air.
A Word About Coatings
If you are using an anti-reflective coating, you don’t need a polysiloxane coating. If you decide
not to, we recommend CR-39 without a protective coat. In all cases, you must adhere to the
minimum tilt angle specified in Table 2-2. As a final note, we recommend that you recess the
exit window to minimize scratches and digs.
Table 2-4 lists some exit window manufacturers and anti-reflection coaters.
Coating 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. Coating
shall meet the hardness adherence requirements of
MIL-M-13508.
Table 2-4. Exit Window Manufacturers and Coaters
Company Discipline Specifics
Evaporated Coatings, Inc.
2365 Maryland Road
Willow Grove, PA 19090
(215) 659-3080 Anti-reflection coater Acrylic window supplier
Anti-reflection coater
Table 2-3. Suggested Window Properties