User`s manual

42 Piranha HS 4x User’s Manual
03-32-10040-03 PRELIMINARY DALSA Corp.
Magnification and Resolution
The magnification of a lens is the ratio of the image size to the object size:
m
h
h
=
′
where m is the magnification, h’ is the image height
(pixel size) and h is the object height (desired object
resolution size).
By similar triangles, the magnification is alternatively given by:
m
f
OD
=
′
These equations can be combined to give their most useful form:
′
=
′
h
h
f
OD
This is the governing equation for many object and
image plane parameters.
Example: An acquisition system has a 512 x 512 element, 10µm pixel pitch area scan camera,
a lens with an effective focal length of 45mm, and requires that 100µm in the object space
correspond to each pixel in the image sensor. Using the preceding equation, the object
distance must be 450mm (0.450m).
10
100
45
450 0 450
µ
µ
m
m
mm
OD
OD mm m==(. )