Symbol SE 2223, Integration Manual

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SE 2223/3223 Scan Engine Integration Guide
CR-39
A thermal-setting plastic produced by the cell casting process. Excellent chemical and
environmental resistance. Good surface hardness, so does not have to be hard-coated, but
may be for severe environments. Reasonably good impact resistance. Most plastic eye
glasses sold today are uncoated, cell cast CR-39. Cannot be ultrasonically welded.
Commercially Available Coatings
Note: You may not be able to ultrasonically weld these 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 scanner. 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. Anti-reflection
coatings on the inside of the window is highly recommended because coating on the
outside is subject to scratching.
Table 2-3. Suggested Window Properties
Material Red cell cast acrylic
Spectral Transmission 85% minimum from 630 to 680 nanometers
Thickness .060 ±.005
Wavefront Distortion (transmission)
0.2 wavelengths peak-to-valley maximum over any
.08 in. diameter within the clear aperture
Clear Aperture To extend to within .04 in. of the edges all around
Surface Quality 60-20
Coating
Both sides to be anti-reflection coated to provide
0.5% max reflectivity (each side) from 630 to 680
nanometers at nominal window tilt angle. Coating
must meet the hardness adherence requirements
of
MIL-M-13508.