Tech Briefs Magazine - November 2021 - PIT-19

Designing Lenses for UAVs and
Drones
State-of-the-art technologies are being
utilized to meet UAV and drone optical
requirements. These include innovative
optical and mechanical designs, exotic
materials, and unique lens manufacturing
and coatings technologies.
Continuous zoom lenses address the
low-SWaP challenge while keeping high
optical performance. These lenses are
smaller and lighter than using multiple
1-FOV lenses. In addition, a continuous
zoom lens enables better mission flexibility
by allowing changes in magnification
during a UAV operation.
Working in collaboration with defense
and commercial customers, Ophir, for
example, has developed a range of lightweight,
high-performance thermal imaging
zoom lenses that are designed specifically
for use in UAV payloads, drones,
and handheld devices. The advanced
zoom lenses use a sophisticated optomechanical
design, to ensure that the lenses
are the smallest, lightest, and most compact,
while still achieving the high levels
of IR thermal imaging performance.
Figure 1(a) shows the LightIR 20275mm
f/5.5 lightweight zoom lens, and
its opto-mechanical layout. The innovative
opto-mechanical design resulted in
a weight of only 264 grams. Despite the
challenging SWaP restrictions, the
advanced lightweight design resulted in
a high level of MTF values across the
entire field, as shown in Figure 1(b).
Moreover, the selection of advanced
materials enabled unique athermalization
properties, maintaining the highest
performance over a wide operating temperature,
in the range of -35°C to +65°C.
The characteristics of this lens lead to
long operational ranges relative to the
lens size and weight. For example, the
detection range of a 2.3m vehicle would
be around 15 km when integrated with a
23mK NETD, 15µm pixel detector
(based on FLIR92 model calculations).
To the best of our knowledge, this is the
smallest and lightest continuous zoom
lens available today, enabling the highperformance
capabilities of advanced IR
thermal imaging systems in harsh environmental
conditions
and on constrained
platforms.
Another approach to address the low
SWaP challenge includes folded-optics
configurations that are designed especially
for compact gimbaled payloads.
An example is Ophir's folded-optic 16180mm
f/3.6 zoom lens, optimized for
MWIR 10µm pixel detectors.
Figure 2(a) demonstrates the optomechanical
layout and picture of the 16180mm
f/3.6 zoom lens. The design is
based on a standard relay and objective
configuration, with two moving groups
that allow for the change in the focal
length. The materials were selected using
best practices, as well as the athermalization
and achromatization concepts.
The folded-optic design enables long
optical lengths for reduced sensitivity
to tolerances, in a compact configuration,
with a reduced number of optical
elements, while addressing the various
challenges of such a concept. These
include line-of-sight (LOS) stabilization,
and a reduced number of optical
elements, based on our capabilities for
producing aspheric and diffractive surfaces
with exceptional levels of accuracy
and quality.
Cov
ToC
http://info.hotims.com/79419-711 http://info.hotims.com/79419-902
Tech Briefs Magazine - November 2021

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