Shutter types vary to meet
MICHAEL J. TENALIO and TYLER MOORE
From thermography to laboratory research and laser safety, optical shut-
ters play critical roles in system perfor-
mance. To develop products such as
cameras, microscopes, and laser sys-
tems, designers must match custom or
off-the-shelf shutters to the requirements of the systems. In this article,
we describe some of the typical applications and types of shutters best suit-
ed to meet product needs (see Fig. 1
and the table).
Shutters are widely used throughout
the thermography world. The technology is often seen as very similar
when applied to night vision and en-
vironmental assessment applications.
Within each system, shutter surfaces
are used to provide periodic nonunifor-
mity correction (NUC), which results
from the spatial nonuniformity in the
photoresponse of detectors in the focal plane array. It is especially severe in
mid- to far-IR imaging systems. In this
capacity, shutters play a critical function, and each application has slightly different requirements.
As a result, when designing any vari-
ation of a thermography system, opti-
mal performance obtained through col-
laborative efforts between the shutter
team and the camera development team
will make sure all specifica-
tions are met. Often, key re-
quirements such as shock and
vibration, operating tempera-
ture, speed, shutter life, pow-
er management, size, weight, and price
point can drastically change the design.
Night vision is the most well-known
example of shutter use in thermography. It is commonly seen in IR imaging systems that are used in weapon
sights and security cameras. A less-
known application of a shutter used
in thermography is environmental assessment, which could be for first responders, industrial manufacturing,
driving safety, inspection, or border
security. Requirements vary for each
example of environmental assessment.
Thermographic IR cameras used by
emergency first responders are an in-
teresting example of cameras being ap-
plied for environmental assessment.
The emergency team needs to analyze
a dangerous structural fire before en-
tering the area. The team lead-
er uses a commercially avail-
able thermographic camera
to analyze the scene for image
hotspots—this often requires
a ruggedized system that can handle
very aggressive use.
The same type of camera could be
used in a different way by a building inspector, who will analyze the thermographic signature to evaluate a build-
ing’s environmental efficiency. Heating
or ventilation leaks can be identified or
the wiring inspected for flaws. Portable
IR cameras for these applications are
typically handled with care. But even
within these examples, a camera system may be designed to reach different target markets or end users.
Hybrid cameras are also available
and require even more attention to
detail. With the right product design,
complicated optical, mechanical, and
electronic challenges can be neutral-
ized, and the result is a simpler, easy-to-use product.
Exposure control in the lab
A shutter is typically the most com-
mon and effective way to achieve
The design of OEM products for
widely different optical applications
benefits from collaboration and
understanding shutter options.