Imaging Resource Guide
8 +44 (0)1904 788600 • EDMUND OPTICS® imaging lenses filters microscopy cameras illumination targets imaging resource guide
Whether your application is in machine vision, life sciences, security,
or tra c solutions, understanding the fundamentals of imaging
technology signi cantly eases the development and deployment of
sophisticated imaging systems. While advancements in sensor and
illumination technologies suggest limitless system capabilities, there
are physical limitations in the design and manufacture of these technologies.
Optical components are not an exception to such limitations,
and optics can often be the limiting factor in a system’s performance.
The content provided in this guide is designed to help you
specify an imaging system, maximize your system’s performance,
and minimize cost.
Section 1: Getting Started
Section 1.1: 11 Best Practices for
We have compiled a number of best practices for creating sophisticated,
cost-e ective imaging systems that are applicable for most
applications. While the following list is nearly exhaustive and should
be considered when designing any imaging system, every application
is unique and additional considerations may be required.
E O Best Practice #1: Bigger, in many cases, is better.
Allow ample room for the imaging system.
Understanding a system’s space requirements before building is especially
true for high resolution and high magni cation requirements.
While recent advancements in consumer camera technology have
yielded strong results in a small package, they still do not approach
the capabilities required for even intermediate-level industrial imaging
systems – partially because of their size limitations. Many applications
can require complex light geometries, large diameter and long
length lenses, and large cameras, in addition to the cabling and power
sources required to operate some of the equipment. Avoid having to
make sacri ces to system performance just because the system’s space
requirements were not considered. It is often advantageous to specify
the vision portion of a system rst, as it is typically easier to arrange
the electronics and mechanics around the vision portion rather than
the other way around. It is also important to remember that the illumination
scheme is part of the vision system, and the geometry of the
object under inspection can often necessitate the use of a large light
source such as a di use dome (see EO Best Practice #4).
E O Best Practice #2: Don’t believe your eyes.
The human eye and brain work together to form an extremely advanced
imaging and analysis system that is capable of lling in information
that is not necessarily there. Additionally, humans see and
process contrast di erently than imaging systems. Software analysis
should be used to ensure image quality and performance requirements
are met. Images that look good to a human viewer may not be
usable with an algorithm.
E O Best Practice #3: Danger! Don’t get too close.
Due to the constraints of physics, attempting to look at fields of
view that are too large relative to a lens’s working distance places
excessive demands on the design of the optical component and
can decrease system performance. It is recommended that a lens
be chosen such that the working distance is roughly two to four
times as long as the desired field of view is wide, in order to
Best Practice #1 and #3: If a 100 mm eld of view is required,
it is recommended that the system’s working distance be
200 - 400 mm. It may be possible that the system’s performance
requirements can be met at WD to FOV ratios approaching or
exceeding 1 to 1, however, potentially signi cant cost and performance
tradeo s may be necessary.
Figure 1.1: Two lens designs, 1.1a and 1.1b, with the same eld
of view and very di erent working distances.
Both lenses in Figure 1.1a and Figure 1.1b are imaging the same
eld of view onto the same sensor, but the lens in a has a working
distance of half of its eld of view, while the lens in b has a
working distance of 3X its eld of view. The light passes through
the lens in a at extreme angles and the light on the edges of the
eld of view (magenta/red) have a much longer distance to travel
than the light in the center of the eld of view (blue). In contrast,
the lens in b achieves the same eld of view at shallower angles
with a smaller path length di erence. As a result, the lens in b
features a much less complex lens design and provides superior
performance at a lower cost.
maximize performance while minimizing cost and complexity.
Remember EO Best Practice #1 and consider the imaging system’s
space requirement before building the system.
This practice also applies to the relationship between sensor size and
focal length. It is best to have focal length to sensor diagonal ratios of
two to four to maximize performance.