Mitsubishi Electric KD Series User Manual page 28

【Depth of Focus】
Definition of resolution
Object Image (erected and
Depth of Focus on KD series
Distance from the focal point (mm)
Scan images
3mm 2mm
TM-XH719C
2-3 Definition
same size)
Focal point
(12mm above from
glass surface）
1mm 0mm
(focal point)
COPYRIGHT©2017-2020 MITSUBISHI ELECTRIC CORPORATION. ALL RIGHTS RESERVED.
【Definition of CIS output】
6. DOF : Depth of Focus
Depth of Focus indicates a change of a focus performance
on various positions of the object from focal position on a
lens-axis.
Generally, the resolution becomes lower or defocused
when the scanning position is moved away from a focal
point.
The resolution is defined as MTF (Modulation Transfer
Function) value.
The MTF value is calculated by the following formula when
scanning a reference chart having a respective width and
pitch of the white and black areas.
MTF =
•lp/inch: lp/inch explains the resolution. The resolution is
defined by reading the black and white same-width stripes.
This pair of the same-width black and white stripe is called
as "line pair" (lp), and the "lp/inch " shows how many "lp"s
are printed in 1 inch.
-1mm
For example, "150 lp/inch chart" means that 150 pairs of
black and white stripes are printed in 1 inch on the chart.
And, the calculation of the resolution is 25.4 (mm) / 300
(stripes) = 84.66, which is about 85μm width strips are
printed .
Vpmax. －Vpmin.
× 100 (%)
Vpmax. ＋ Vpmin.
28