Tech Briefs Magazine - November 2021 - PIT-20

Figure 2(b) shows the MTF results as a
function of spatial frequency of the 16180mm
folded design for the WFOV and
NFOV, illustrating the capabilities of the
design to obtain near diffraction limit
performance. As can be seen, the high
MTF performance of this design is maintained
across the entire field and, even
at the corners, the performance is more
than reasonable.
Diamond turning technology is often
used to produce aspheric and diffractive
surfaces, with exceptional levels of accuracy
and quality. Aspheric lens surfaces
are desirable, particularly when it comes
to infrared optics, showing significant
increases in optical performance over
their spherical counterparts. AsphericDiffractive
lens surfaces allow for the
integration of multiple functions, such
as chromatic and spherical aberration
corrections. Lenses produced by diamond
turning can therefore combine
multiple elements, reducing overall size
and weight.
The use of durable, anti-reflective lens
coatings also improves the optical performance,
without any impact on the size or
weight of the lens. Lens coatings maximize
transmission by reducing reflection losses.
Advanced coating techniques can be used
to produce tailor-made coatings. These
coatings can be designed to meet the needs
of the UAV industry, where drones may be
deployed in a variety of environments, each
presenting its own optical challenges.
SWaP Lenses
When it comes to optics for UAVs,
payloads, drones, and handheld device
applications, your optics should incorporate
the following capabilities:
* Small form factor lenses to fit miniature
gimbals;
* Ultra-light weight zoom & fixed focus
lenses;
* High optical performance;
* Low power consumption;
* High durability (HD) or low reflection
hard carbon (LRHC) AR coatings;
* Fast FOV change;
* Continuous zoom, with fixed F# maintained
through the full zoom range;
* Accurate thru-zoom bore sight;
* Compatible with major MWIR & LWIR
detectors;
* Diffraction-limited optical design.
Conclusion
Advanced optical solutions are the
key to airborne mission performance
for guaranteed high imaging quality
20
Cov
ToC
(a)
ENVELOPE (FROM CUSTOMER)
109.86
100.5
L0S
Ø38
45°
24.77
45
45°
FPA
6.6
30.99
FPA
6.73
15.1
38.73
L0S
48.09
1
(b)
TS Diff. Limit
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
4
8
12
16
20
24
28
Spatial Frequency in cycles per mm
32
36
40
TS 0.000, 0.0000 mm
TS 0.0000, 2.4000 mm
NFOV (180mm EFL) MTF, 3800-4200nm
TS 3.2000, 0.0000 mm
TS 0.0000, -2.4000 mm
TS -3.2000, 0.0000 mm
TS 3.2000, 2.4000 mm
TS 3.2000, -2.4000 mm
TS -3.2000, 2.4000 mm
TS -3.2000, -2.4000 mm
1.0
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
TS Diff. Limit
WFOV (16mm EFL) MTF, 3800-4200nm
TS 0.0000, -2.4000 mm
TS 0.0000, 0.0000 mm
TS 0.0000, 2.4000 mm
TS 3.2000, 0.0000 mm
TS -3.2000, 0.0000 mm
TS 3.2000, 2.4000 mm
TS 3.2000, -2.4000 mm
TS -3.2000, 2.4000 mm
TS -3.2000, -2.4000 mm
4
8 12
16 20 24
28 32
Spatial Frequency in cycles per mm
Figure 2. (a) Opto-mechanical layout and picture, (b) MTF characteristics.
without a heavy toll on the UAV payload.
UAVs and drones equipped with
the ultimate detectors, image processing
software, and monitors must also be
equipped with a high-performance lens,
otherwise risking poor image quality.
Optics for UAVs and drones must meet
the strict constraints known as 'SWaP'
(Size, Weight, and Power consumption).
Meeting these constraints presents challenges
to optical lens manufacturers, who
must deliver compact, lightweight, and
high-performance lenses to operate
under harsh environmental conditions.
These constrains are met using cuttingedge
manufacturing technologies, and
unique opto-mechanical designs. As an
example, Ophir has successfully designed
and implemented advanced IR zoom
lenses with reduced SWaP based on a
unique folded-optic design, suitable for
10µm pixel size, as well as lightweight
opto-mechanical concepts with relatively
long focal lengths. Both lenses demonstrate
MTF performance close to the diffraction
limit, and capabilities for longrange,
high-resolution vision and identification
in harsh environmental conditions,
and on constrained platforms.
Such advanced IR optical assemblies
meet the challenging UAV industry
requirements and open-up new opportunities
in next generation UAV and drone
thermal imaging applications.
This article was written by Dr. Kobi Lasri,
General Manager, Ophir Optronics Solutions,
MKS Instruments Inc. (Jerusalem, Israel). For
more information, contact Dr. Lasri at mktg@
mksinst.com, or visit http://info.hotims.com/
79419-222.
References
1. Teal Group (2017) - https://www.
tealgroup. com/index. php/pages/pressreleases/54-teal-group-predicts-worldwide-civil-drone-production-will-soar-overthe-next-decade
2.
Gettinger, D. (2017). Public Safety Drones.
Retrieved from Center for the Study of the
Drone - https:// dronecenter.bard.edu/
files/2017/04/CSD-Public-Safety- DronesWeb.pdf
Photonics
& Imaging Technology, November 2021
36 40
20Modulus
of the OTF
96.21
Ø58
Ø58.6
MAX CLEAR APERTURE
(LENS OUTSIDE DIAMETER)
Ø51.5
Modulus of the OTF

http://info.hotims.com/79419-222 https://www.tealgroup.com/index.php/pages/press-releases/54-teal-group-predicts-worldwide-civil-drone-production-will-soar-overthe-next-decade https://dronecenter.bard.edu/files/2017/04/CSD-Public-Safety-Drones-Web.pdf http://info.hotims.com/79419-902

Tech Briefs Magazine - November 2021

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