Exit Window Recommendations; Avoiding Scratched Windows; Window Material; Exit Window Properties - Datalogic DSE0420 Integration Manual

Exit Window Recommendations

Avoiding scratched windows

Scratches on the exit window can strongly affect the reading performance. It
is recommended to use an exit window having a scratch-resistant coating
and to position the engine window in a recessed position.

Window material

The exit window is an integral part of the imaging system and should be
designed and selected to preserve the optical quality of the system. It is rec-
ommended to use only cell-cast plastics or optical glass.
Common materials and their characteristics are shown in
Table 1. Exit window materials
Properties
Optical Quality
Surface Hardness
Impact Resistance
Chemical / UV Resistance
Ultrasonically Welding

Exit window properties

Recommended properties/performance of the exit window are reported in
Table
Table 2. Exit Window Properties
Characteristics
Material
Thickness
Wavefront distortion
Clear aperture
Surface quality
AR coating
Integration Guide
The use of a double-sided AR coated exit window is strongly rec-
ommended.
PMMA
(cell cast acrylic or
polymethyl methacrylic)
Very good
Hard coating required
Good
Susceptible
Compatible
2.
Requirement
PMMA or CR39 or equivalent
1.5mm
0.2 wavelengths peak-to-valley maximum and
0,04λ
aperture
To extend to within 1.0mm of edges all around
60/20 scratch/dig
• double sided
• transmittance > 97% minimum within spectrum range
400nm-750nm.
• reflections max 0,4% per side in the range 620nm-640nm
maximum rms over any 2.0mm diameter within the clear
Key Parameters
Table 1below.
CR39
(Allyl Diglycol
Carbonate)
Very good
Hard coating required
Good
Susceptible
Compatible
7