Opticon NLB 9625, User Manual

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Manual No. 25-NLB0045-01
Series NLB-9625/9645 Mini Laser Fixed Position Scanner
Page 8
Depth-of-Field
Just as with a camera, the scanner has a depth-of-field. It can read bar codes that are not precisely at the
focal distance

maybe a little closer, or a little farther away. However, if the bar code label is positioned too
far from the focal distance, the scanner may not be able to successfully decode it.
The depth-of-field varies based on the density of the bar code, i.e., the thickness of the bars. Very high
density bar codes (which have very narrow bars) are readable over a much shorter distance range than low
density bar codes with larger bars.
The following table shows the “typical” depth-of-field (closest to farthest reading distances) for the NLB-
9625/9645 Series scanners. The actual performance may differ slightly from unit to unit. Also, it is important
to note that this data was measured under ideal conditions using high quality bar code labels. In a “real
world” environment the conditions will not be as ideal. Therefore, the best practice is to position the scanner
at its focal distance rather than at the extremes of its depth-of-field.
Typical Reading Distance from Window
(Depth-of-Field)
9626
Side View
9627
Front View
9646
Side View
9647
Front View
Bar Code
Density
Min. Max. Min. Max. Min. Max. Min. Max.
13.0 mil 0.0” 7.0” 1.1” 8.0” 0.5” 7.5” 2.0” 9.5”
10.0 mil 0.5” 6.0” 2.4” 7.4” 1.9” 6.5” 3.5” 7.0”
7.5 mil 1.8” 5.4” 3.4” 6.5” 2.2” 5.6” 3.8” 6.5”
Readable Bar Code Width (Field-of-View)
The following table shows the field-of-view at various distances from the window. The field-of-view is the
max. width that the scanner is capable of reading. A bar code label positioned anywhere within this field-of-
view can be decoded. The field-of-view is also a measure of the widest bar code label that can be read.
Remember, the width of a bar code label includes not only the bars and spaces but also the required white
space (quiet zone) on each end.
Field-of-View
(Maximum Readable Bar Code Width)
Distance
from Window
9627
Front View
9647
Front View
9626
Side View
9646
Side View
2 inches 2.6” 2.6” 3.8” 3.8”
3 inches 3.3” 3.3” 4.8” 4.8”
4 inches 4.3” 4.3” 5.7” 5.7”
5 inches 5.1” 5.1” 6.6” 6.6”
6 inches 5.9” 5.9” 7.8” 7.8”
7 inches 6.8” 6.8” N/A N/A
Good design policy is to position the scanner at its focal distance and at the center of the field-of-view. Do not
position it near the extremes of the reading range.